United States
Environmental Protection
Agency
Office of Emergency and
Remedial Response
Washington, DC 20460
PB92-963405
Publication 9360.4-04
May 1992
Superfund
Compendium of ERT
Field Analytical
Procedures
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OSWER Directive 9360.4-04
May 1992
COMPENDIUM OF ERT FIELD
ANALYTICAL PROCEDURES
Sentex Scentograph Gas Chromatograph
Portable XRF Analyzer
Photoionization Detector -- HNU
Photovac 10A10 Portable Gas Chromatograph Operation
Photovac 10S50, 10S55, and 10S70 Gas Chromatograph Operation
Photovac GC Analysis for Air, Soil Gas, Water, and Soil
Micromonitor M200
Interim Final
Environmental Response Team
Emergency Response Division
Office of Emergency and Remedial Response
U.S. Environmental Protection Agency
Washington, DC 20460
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Notice
This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved
for publication. Mention of trade names or commercial products does not constitute endorsement or
recommendation for use.
The policies and procedures established in this document are intended solely for the guidance of government
personnel, for use in the Superfund Removal Program. They are not intended, and cannot be relied upon, to
create any rights, substantive or procedural, enforceable by any party in litigation with the United States. The
Agency reserves the right to act at variance with these policies and procedures and to change them at any time
without public notice.
Depending on circumstances and needs, it may not be possible or appropriate to follow these procedures exactly
in all situations due to site conditions, equipment limitations, and limitations of the standard procedures.
Whenever these procedures cannot be followed as written, they may be used as general guidance with any and
all modifications fully documented in either QA Plans, Sampling Plans, or final reports of results.
Each Standard Operating Procedure in this compendium contains a discussion on quality assurance/quality
control (QA/QC). For more information on QA/QC objectives and requirements, refer to the Quality
Assurance/Quality Control Guidance for Removal Activities, OSWER directive 9360.4-01, EPA/540/G-90/004.
Questions, comments, and recommendations are welcomed regarding the Compendium of ERT Field Analytical
Procedures. Send remarks to:
Mr. William A. Coakley
Removal Program QA Coordinator
U.S. EPA - ERT
Raritan Depot - Building 18, MS-101
2890 Woodbridge Avenue
Edison, NJ 08837-3679
For additional copies of the Compendium of ERT Field Analytical Procedures, please contact:
National Technical Information Service (NTIS)
U.S. Department of Commerce
5285 Port Royal Road
Springfield, VA 22161
(703) 487-4600
ii
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Table of Contents
Section Page
1.0 SENTEX SCENTOGRAPH GAS CHROMATOGRAPH: SOP# 1702
1.1 Scope and Application 1
1.2 Method Summary 1
13 Sample Preservation, Containers, Handling, and Storage 1
1.4 Interferences and Potential Problems 1
13 Equipment/Apparatus 2
1.6 Reagents 2
1.7 Procedures 2
1.7.1 Calibration 2
1.7.2 Sampling 3
1.8 Calculations 3
1.9 Quality Assurance/Quality Control 3
1.10 Data Validation 4
1.11 Health and Safety 5
2.0 PORTABLE XRF ANALYZER: SOP #1707
2.1 Scope and Application 7
2.2 Method Summary 7
23 Sample Preservation, Containers, Handling, and Storage 7
2.4 Interferences and Potential Problems 7
2.5 Equipment/Apparatus 8
2.6 Reagents 8
2.7 Procedures 8
2.7.1 Calibration 8
2.7.2 In situ Soil Analysis 9
2.73 Soil Sample Analysis 9
2.8 Calculations 10
2.9 Quality Assurance/Quality Control 10
2.10 Data Validation 11
2.11 Health and Safety 11
3.0 PHOTOIONIZATION DETECTOR -- HNU: SOP #2056
3.1 Scope and Application 13
3.2 Method Summary 13
33 Sample Preservation, Containers, Handling, and Storage 14
3.4 Interferences and Potential Problems 14
3.4.1 PID Instrument Limitations 14
3.4.2 Regulatory Limitations 16
3.5 Equipment/Apparatus 16
iii
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3.6
3.7
Reagents
Procedures
16
16
3.7.1 Start-Up 16
3.7.2 Field Operation 17
3.73 Post Operation 18
3.8 Calculations 18
3.9 Quality Assurance/Quality Control 18
3.10 Data Validation 18
3.11 Health and Safety 18
4.0 PHOTOVAC 1QA10 PORTABLE GAS CHROMATOGRAPH OPERATION: SOP #2107
4.1 Scope and Application 19
4.2 Method Summary 19
43 Sample Preservation, Containers, Handling, and Storage 19
4.4 Interferences and Potential Problems 19
4.5 Equipment/Apparatus 19
4.6 Reagents 20
4.7 Procedures 20
4.7.1 Laboratory Operation 20
4.7.2 Calibration 20
4.7.3 Field Operation 21
4.7.4 Shut Down 21
4.8 Calculations 21
4.8.1 Calibration Curve 21
4.8.2 Standard Response Generation/Duplication of 22
Factory Calibration Data
4.9 Quality Assurance/Quality Control 22
4.10 Data Validation 22
4.11 Health and Safety 22
5.0 PHOTOVAC 10S50, 10S55, AND 10S70 GAS CHROMATOGRAPH OPERATION: SOP #2108
5.1 Scope and Application 23
5.2 Method Summary 23
53 Sample Preservation, Containers, Handling, and Storage 23
5.4 Interferences and Potential Problems 23
5.5 Equipment/Apparatus 23
5.5.1 Equipment List 23
5.5.2 Carrier Gas Supply System Options 24
5.6 Reagents 24
5.7 Procedures 25
5.7.1 Shipping 25
5.7.2 Pre-Operational Check Out 25
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5.73 Carrier Gas Flow Rate Adjustment 25
5.7.4 Photovac Settings 25
5.7.5 Calibration 27
5.7.6 Shut down 28
5.8 Calculations 28
5.8.1 Calibration Curve 28
5.8.2 Standard Response Generation/Duplication of 28
Factory Calibration Data
5.9 Quality Assurance/Quality Control 29
5.10 Data Validation 29
5.11 Health and Safety 29
6.0 PHOTOVAC GC ANALYSIS FOR AIR, SOIL GAS, WATER, AND SOIL; SOP #2109
6.1 Scope and Application 31
62 Method Summary 31
6.2.1 Air and Soil Gas Samples 31
6.2.2 Water Samples 31
6.23 Soil Samples 31
63 Sample Preservation, Containers, Handling, and Storage 31
63.1 Air and Soil Gas Samples 31
63.2 Water Samples 31
633 Soil Samples 32
6.4 Interferences and Potential Problems 32
6.4.1 All Samples 32
6.4.2 Air and Soil Gas Samples 32
6.43 Water and Soil Samples 32
6.5 Equipment/Apparatus 32
6.5.1 Photovac Operation 32
6.5.2 Soil Gas Analysis 33
6.53 Tenax/CMS Sampling 33
6.5.4 Water Headspace Analysis 33
6 J J Soil Headspace Analysis 33
6.6 Reagents 33
6.6.1 Air Sample Analysis 33
6.6.2 Water and Soil Sample Analysis 33
6.7 Procedures 33
6.7.1 Method Detection Limits 33
6.7.2 Calibration 34
6.7.3 Operation 34
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6.8 Calculations 36
6.8.1 Air and Soil Gas Samples 36
6.8.2 Water Samples 36
6.83 Soil Samples 36
6.9 Quality Assurance/Quality Control 36
6.9.1 Blanks 37
6.9.2 Spikes 37
6.93 Confirmatory Analysis 37
6.10 Data Validation 38
6.11 Health and Safety 38
7.0 MICROMONITOR M200: SOP #2111
7.1 Scope and Application 39
7.2 Method Summary 39
73 Sample Preservation, Containers, Handling, and Storage 39
7.4 Interferences and Potential Problems 39
7.5 Equipment/Apparatus 40
7.6 Reagents 40
7.7 Procedures 40
7.7.1 Macintosh Software 40
7.7.2 Calibration 41
7.73 Sample Analysis 42
7.8 Calculations 42
7.9 Quality Assurance/Quality Control 42
7.10 Data Validation 42
7.11 Health and Safety 43
APPENDIX A Ionization Potentials 45
APPENDIX B Photovac Maintenance and Calibration 57
APPENDIX C Troubleshooting Guides 63
APPENDIX D Figures 71
REFERENCES 81
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List of Exhibits
Exhibit
SOP
Page
Table 1
Scentograph Operating Parameter Menu
1702
4
Table 2
Relative Photoionization Sensitivities for Various Gases
2056
14
Table 3
Typical Applications of Interchangeable Probes
2056
15
Table 4
Operating Conditions for Micromonitor M200
2111
41
Appendix A
Ionization Potentials
2056
45
Appendix B
Photovac Maintenance and Calibration Schedule
(Table F)
2107,
2108
57
Figure 1
Pneumatics of Photovac 10S Series
2108
73
Figure 2
Micromonitor M200 Front Panel
2111
75
Figure 3
Systems Setup
2111
77
Figure 4
Micromonitor Back Panel
2111
79
vii
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Acknowledgments
Preparation of this document was directed by William A. Coakley, the Removal Program QA Coordinator of
the Environmental Response Team, Emergency Response Division. Additional support was provided under U.S.
EPA contract #68-03-3482 and U.S. EPA contract #68-WO-0036.
viii
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1.0 SENTEX SCENTOGRAPH GAS CHROMATOGRAPH: SOP #1702
1.1 SCOPE AND APPLICATION
This Standard Operating Procedure (SOP) primarily
deals with the assessment of gaseous matrix
samples. The Sentex Scentograph Gas
Chromatograph (GC) can work in two detector
configurations: the Electron Capture Detector
(ECD) or the Argon Ionization Detector (AID).
The ECD analyzes volatile chlorinated compounds,
as it is very sensitive to electrophilic compounds
such as chlorinated organics. The AID is a more
universal detector, responding to most compounds
with ionization potentials at or below 11.7 eV. It
will respond to most aromatic compounds and many
chlorinated compounds of environmental interest.
At present, only vapor-phase samples (e.g., soil gas
samples, Tedlar bag gas samples, and ambient air
samples) are analyzed through the activation of the
instrument's internal sampling pump. The Sentex
GC unit does have a syringe injection port, but this
is not being used for any ERT applications at
present. An optional purge and trap unit is
available to determine purgeable organics in soil or
water matrices. However, this SOP does not cover
that capability.
1.2 METHOD SUMMARY
The initial step in Sentex Scentograph Gas
Chromatograph sampling is to turn on and boot the
Toshiba T1100 computer. The computer runs the
data acquisition program and stores all parameters
and data. Begin by inserting the program disk "A"
and the data "B" disk into the appropriate upper
and lower disk drives of the computer. Next, turn
on the Sentex GC and, following the menu prompts,
enter the GC operational parameters into the
computer. Calibration analysis is then performed
and stored. Calibration standards can be run either
in the field, or in the laboratory prior to field
sampling. In the latter case, a field calibration run
must still be conducted to ensure that the lab
calibrations are valid. A Tedlar bag of a standards
mixture can be attached to the Sentex GC upper
inlet port at this point, or the internal calibration
gas cylinder can be used. Once calibration analysis
is validated and stored, a Tedlar bag containing an
unknown sample is attached to the Sentex GC's
lower sampling inlet port, and the bag valve is
opened. By selecting Function #J from the
computer menu, a manual analysis can be run.
Once the sampling pump stops, the valve of the
sample bag is dosed, and the entire bag is removed
from the inlet port and stored for future laboratory
analysis.
While this procedure is standard for all Sentex GC
sampling, actual operating conditions (e.g., detector
used, column packing material, oven temperature)
will vary as required by the sample matrix
encountered, and by the physical and chemical
nature of the samples analyzed. New operating
parameters are determined as new target
compounds are selected for analysis.
1.3 SAMPLE PRESERVATION,
CONTAINERS, HANDLING, AND
STORAGE
The vast majority of Sentex applications are for soil
gas analysis. These soil gas samples are collected
and stored as outlined in ERT SOP #2149, Soil Gas
Sampling
1.4 INTERFERENCES AND
POTENTIAL PROBLEMS
Since the Sentex units use gas chromatography,
target compounds are identified by retention time
indices (RTI). If the RTI of the sample peak(s)
matches the RTI of the standard peak(s), it is
assumed to be identical. If any non-target
compound has the same RTI, it can be misidentified
as a target compound. This problem occurs more
frequently with the AID, since it will respond to any
compound at or below 11.7 eV. Often, soil gas
samples will have very high (ppm) levels of Q to C6
hydrocarbons, as well as low (ppb) levels of target
compounds. The AID will respond to these
hydrocarbons, whose signal often can "swamp* or
obscure the signal of the lower level target
compounds. In this case, it is better to use the
ECD. If this is not possible, a different GC column
(one able to separate the target compounds from
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the interference of the sample matrix) must be
utilized. Moisture within the Tedlar bags will yield
interference peaks that can obscure the resolution
of the target compounds. It has not been
determined whether the moisture itself, or
contaminants in the moisture, yields these
contamination peaks, but the effect is seen on both
the AID and the ECD. Typically, when water is
found in the Tedlar bags, the results of that bag's
analysis are considered questionable. Typical
ambient air relative humidity has no appreciable
effect on the signal response.
1.5 EQUIPMENT/APPARATUS
A Sentex model Scentograph GC can be configured
for AID or ECD. Interfaced with the unit is a
Toshiba model T1100 lap top computer which runs
the data acquisition program and stores all
parameters and data. The Sentex unit has an
internal battery pack which is charged from a Power
Sonic Corporation model PSC-12400 (115 VAC to
12 VDC) charger. Attached to the T1100 is a
Hewlett-Packard Model 2225P Think Jet printer
which produces hard copies of chromatograms and
peak data information. No other equipment is
required to operate the Sentex Scentograph unit.
1.6 REAGENTS
The Sentex AID requires ultrahigh purity (99.99%
or above) Argon as carrier gas. The ECD can use
either ultrahigh purity Argon or Helium (these can
be ordered from Scott Gas, Matheson or any other
reliable vendor). Gas standards are purchased as
certified mixtures from Scott Gas or Matheson, at
fairly high concentrations (i.e., 1-50 ppm). These
concentrations subsequently dilute to various
concentrations that enable construction of a
standard calibration curve. If the internal
calibration cylinder is used, a low-level standard,
such as 0.5-1.0 ppm, should be used.
If liquid phase standards are required, they must
also be of the highest purity, such as Aldrich Gold
Label or Supelco Environmental standards kits. If
air is to be used for sample/standards dilutions, it
must also be ultrahigh purity gas.
1.7 PROCEDURES
All operational parameters are entered from the
T1100 computer and accessed from the operations
menu, Function #7, which appears when the Sentex
unit is turned on. Once the parameters are entered,
run for calibration, Function #4. This is not a true
calibration, since the Sentex calculates a pseudo-
concentration against only one concentration. The
calibration function is used only when operating
parameters under Function #i are changed. In all
other cases, it is ignored. After the first "junk" or
noise peak is identified in the calibration run, the
run is typically aborted. Occasionally, a Tedlar bag
or the internal calibration gas cylinder can be
sampled in the calibration mode, but this would be
only for peak identification and semi-quantification
purposes, since it is a single point calibration.
1.7.1 Calibration
The generation of calibration standards to be run in
the field can be performed either in the field or in
the laboratory prior to entering the field. If the
latter is done, field standards must still be run to
ensure calibration runs stored on the data disks are
valid and close to standards run in the lab.
Dilutions are typically made from the certified gas
standards' cylinders using Hamilton 500, 1000 and
1500 cm3 model "Super syringes", and from Tedlar
sampling bags. Simple volumetric dilutions are
made and the set of standards analyzed as if they
were typical samples.
At least three concentrations of each standard must
be run; however, more standards are run to
establish the minimum ranges for the linear
response of the Sentex detectors for each individual
target compound. In the laboratory, a Multi-
Channel Mass Flow Control can be used to meter
selected flow rates from two to four separate
compressed gas cylinders. Establish a continuous
flow of a selected concentration of mixtures to
either fill Tedlar bags for analysis or to create a
flow-through-cell from which the Sentex GC can
sample. This method has been used extensively to
establish minimum and maximum detection levels in
an efficient and timely manner.
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1.7.2 Sampling
Follow this procedure for analyzing Tedlar bags
with the Scentograph.
1. Insert Disks "A" and "B" into upper and lower
T1100 disk drives respectively, and turn on
Sentex GC.
2. Follow menu prompts and input GC
parameters according to Table 1, Scentograph
Operating Parameter Menu.
3. Select Function #4 to run and store calibration
analysis.
4. Attach Tedlar bag with unknown sample to
lower sample inlet port and slide bag valve
down to open.
5. Select Function #3 to run a manual analysis.
Type the sample name; press < ENTER > a
second time to inject.
6. Immediately after the sampling pump stops,
pull bag valve out to close; remove bag from
inlet port.
7. To abort sample and calibration analysis, hold
down the Reset key on the GC panel until the
"Return" prompt appears.
8. Any changes in operating parameters entered in
Function #1 must be followed by a calibration
run prior to an analysis run.
1.8 CALCULATIONS
A calibration curve of at least three concentrations
must be constructed for each target compound. A
straight line equation in the form of y = (m)(x) +
b (where: x = concentration, y = area counts, m =
slope and b = the intercept) is fit to the standards
raw data. The (y), or the unknown concentration
for the sample, is determined from the above
straight line equation. Non-linear data is indicative
of erroneous detector response. Alternatively,
sample concentration can be calculated as shown
below;
Sample Cone. = (standard area)
(standard area)
The Sentex performs a one point calibration for
those compounds entered in the library. If the
samples and library standard are in the linear range,
this one point calibration is considered valid for
screening purposes.
1.9 QUALITY ASSURANCE/
QUALITY CONTROL
The following QA/QC protocols are applicable:
Run a complete calibration curve daily.
Duplicates of a standard, in the mid-range
of the calibration curve and preferably
close to sample results, should be run every
10 samples or so, to ensure detector
response is constant.
Run two to three duplicates for each
sample and standard. In terms of area
count and retention time values, these
duplicate responses should be within 10-
20% of each other.
Matrix spikes, or spiking samples with
known levels of standards, are not typically
required, as the same Tedlar bag may be
analyzed by other field instrumentation
(e.g., Photovac, OVA, etc.) and/or
collected onto traps for GC/MS
confirmation. If Tedlar bags are used to
prepare standards, the time of preparation
should be noted.
During sample analysis, one of the
standards should be periodically re-
analyzed to test for any sample loss in the
bag over time.
A performance evaluation (PE) sample is
typically sent along with the samples to test
for any loss or contamination from transit
or handling during sampling.
Send a trip blank of zero air along for
analysis at the end of the sampling run to
determine if any contamination of the
Tedlar bags occurred during transit.
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Table 1: Scentograph Operating Parameter Menu
#
Operating Parameter
Example
1
Calibration Sample Name
up to 8 letters
SAMPLE
2
Sample Time
1 300 seconds
15
3
Delay Time
0.1 - 4.0 seconds
1
4
Desorption Time
0.1 - 4.0 seconds
4
5
Inhibit Time
10 - 999 seconds
50
6
Oven Temperature
30ฐ C - 140ฐ C
50
7
Chart Duration
1; 3; 5; 10; 15; 20; 30 minutes
30
8
Analysis per Calibration
1 - 99
99
9
Auto Analysis Duration
0 - 120 minutes
manual
10
Backflush Option
0 = off; 1 = on
11
Detector
1-AID, 2-ECD, 3-TCD, F-PID
AID
12
Column
up to 8 letters
6 ft. 10% CP5
13
Column Pressure
5-40
20
14
Number of Calibration Peaks
1 - 16
1
15
Peak Number 1
Substance Name
Concentration Range
Calibration Concentration
Peak Alarm Values
up to 8 letters
0 = ppm; 1 = ppb
99.9 ppm; 9999ppb
0 - 99.99 ppm; 9999ppb
Ul/AID
PPM
1.00
99
16
Upload Scentograph Parameters
1.10 DATA VALIDATION
As mentioned previously, peak identification is by
retention time index (RTT). Sample spikes, using
known levels of target compounds, can be prepared
to identify the absence/presence of target
compounds in the samples, if peaks are eluting close
to the target compounds. Typically, only the RT1 is
needed to identify the peaks of interest.
Quantification is determined from the linear
calibration curve, and solving for concentration *(y)"
from the straight line equation. The coefficient of
variation on the straight line equation should have
an R squared (R2) of 0.95 or better. Confirming the
identity of any particular target compound must be
done by other analytical methods, typically GC/MS.
Standards must be run along with the samples and
should bracket the levels found in the field samples.
Alternatively, a statistical approach to data
validation can be sought. Once the linear range is
established, an appropriate standard of either low or
midrange concentration will be analyzed 10 or more
times throughout the day. The standard deviation
of the mean (o(n-l)) for the response of the
standard selected is determined. The statistical
method detection limit (MDL) will be three times
the standard deviation (3 a). The method
quantitation limit (MQL) will then be 10 times the
standard deviation (lOo). Results below the MDL
are considered "nondetects" (ND). Results above
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the MDL but below the MQL are considered
"detected", but below the quantitation limit, so are
ascribed a "J" value. This "J" value will flag the data
to let the user know the results are questionable.
Results above the MQL are considered statistically
reliable data.
1.11 HEALTH AND SAFETY
Analysis should be performed in a well-ventilated
room. When liquid reagents are used to prepare
standards, etc., disposable protective gloves and
suitable eye protection should be worn. Work
should be performed under a vented hood.
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2.0 PORTABLE XRF ANALYZER: SOP #1707
2.1 SCOPE AND APPLICATION
The purpose of this Standard Operating Procedure
(SOP) is to describe the procedures for portable
X-ray fluorescence spectroscopy (XRF), an
analytical technique which allows for qualitative and
quantitative analysis of a sample's chemical
composition. In a source-excited XRF analysis,
primary X-rays emitted from a sealed radioisotope
source are utilized to irradiate a sample. These X-
rays cause the sample to emit characteristic
fluorescent X-rays from the elements contained in
the sample. From the energy, or wavelength, of
these fluorescent X-rays, a qualitative analysis can
be made. From the number of X-rays at a given
energy, a quantitative analysis is possible. Solid and
liquid samples can be analyzed with proper X-ray
source selection. Typical environmental applications
are:
heavy metals in soils, sludges, and liquids;
light elements in liquids;
heavy metals in industrial waste stream
effluent;
PCBs in transformer oil by CI analysis; and
heavy metal air particulates collected on
membrane filters.
Measurements may be made in situ, or samples may
be collected, homogenized, and placed into sample
cups for analysis.
2.2 METHOD SUMMARY
XRF instruments use radioactive isotopes, such as
Fe-55, Cm-244, Cd-109 and Am-241, for the
production of primary X-rays. Each source emits a
specific energy range of primary X-rays that causes
a corresponding range of elements in a sample to
produce fluorescent X-rays. When more than one
source excites the elements of interest, the
appropriate source(s) is selected according to its
excitation efficiency for the elements of interest.
For measurement, the sample is positioned in front
of the source-detector window and exposed to the
primary (source) X-rays by pulling a trigger on the
probe (or pushing back the top of the probe unit on
the sample type probe), which exposes the sample
to radiation from the source. The sample's
fluorescent and backscattered X-rays enter through
the detector beryllium (Be) window and are
detected in the active volume of a high-resolution,
gas-filled, proportional counter.
Elemental count rates (the number of net element
pulses per second) are used in correlation with
actual sample compositions to generate calibration
models for qualitative and quantitative
measurements.
The user selects an analysis time from 1 to 32,767
seconds. Generally, the shorter measurement times
(30 s -100 s) are used for initial screening and hot
spot delineation, while longer measurement times
(100 s - 500 s) are used for higher precision and
accuracy requirements.
2.3 SAMPLE PRESERVATION,
CONTAINERS, HANDLING, AND
STORAGE
Use appropriate sample containers (glassware) with
Teflon-lined lids for sample collection. Disposable
31-mm diameter plastic cups are used for XRF
measurements.
2.4 INTERFERENCES AND
POTENTIAL PROBLEMS
Sample Placement. The X-ray signal decreases
the greater the distance from the radioactive
source. Minimize decrease by maintaining the
sample's distance from the source within a 1-
mm range.
Sample Representation. Representation is
affected by the soil macro- and micro-
homogeneity. This can be minimized by either
homogenizing large samples prior to analyzing
an aliquot, or by analyzing several samples (in
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situ) at each sampling point and averaging the
results.
Reference Analysis. XRF soil chemical and
physical matrix effects may be corrected by
using inductively coupled plasma (ICP), or
atomic absorption (AA) spectrometer-analyzed,
site-specific soil samples as calibration samples.
A major source of error can result if the
samples analyzed are not representative of the
site and/or the analytical error is large. With
XRF calibrations based on reference analysis
results, the XRF analytical results may be in the
same units used for the calibration samples
reference analysis. For example, total metals
can be used for comparison using the toxicity
characteristic leachate extraction procedure
(TCLP).
Chemical Matrix Effects. Chemical matrix
effects result from differences in concentrations
of interfering elements. These effects appear as
either spectral interferences (peak overlaps) or
as X-ray absorption/enhancement phenomena.
Both effects are common in soils contaminated
with heavy metals. It is critical to establish all
chemical matrix relationships during the time of
instrument calibration. This is done by using
ICP or AA analyzed soil samples as the XRF
calibration standard (as discussed in Step 3).
Physical Matrix Effects. Physical matrix effects
result from variations in the physical character
of the sample. They include such parameters as
particle size, uniformity, homogeneity and
surface condition. Physical matrix effects can
be minimized by sieving and thoroughly
homogenizing a soil sample prior to analysis.
Ambient Temperature. Changes in ambient
temperature can affect the gain of the
amplifiers producing instrument drift. As long
as the gain control is allowed to make periodic
adjustments however, the unit will compensate
for the influence of temperature on its energy
scale. If increasing or decreasing ambient
temperature is a concern, allow the XRF unit to
gain control after every five measurements.
Moisture Content. Moisture content of soil
samples poses potential interference. Soil
samples should have a percent moisture of no
more than 20%. Dry samples, if necessary.
X-Ray Spectrum Overlap. Certain X-ray lines
from different elements (when present in the
sample) can be very close in energy, and
therefore, interfere by producing a severely
overlapped spectrum. The lead/arsenic overlap
is a typical example.
Pure Element Calibration. When doing the
pure element calibration, be sure to include all
elements of interest at the site, as well as
elements adjacent to the target compound. In
addition to target elements, include all elements
present in detectable amounts with the X-ray
source being used. Use that information to
determine potential spectral interferential effect
on the target element.
2.5 EQUIPMENT/APPARATUS
portable XRF-X-MET model 840, model
880 or equivalent
pure element samples
battery charger
battery pack
31-mm diameter disposable sample cups
polypropylene film, 0.2 mil thickness
plastic bags
20-mesh sieve
moisture balance oven
nylon reinforced, water-repellant backpack
metal reinforced shipping case with die-cut
foam inserts
2.6 REAGENTS
pure element spectral calibration standards
matrix calibration standards ~ ICP- or AA-
analyzed site matrix calibration standards
2.7 PROCEDURES
2.7.1 Calibration
Calibration of the XRF should be based on
previously collected samples which were analyzed by
AA or ICP. The field-portable unit uses samples
collected from the site to generate a calibration
curve.
Samples used for XRF calibration, more commonly
referred to as site-specific calibration standards
8
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(SSCS), must be representative of the matrix and
concentration range which mil be sampled at the
site. For example, if conducting an investigation for
off-site contamination, then SSCS samples should
not come from on site. The matrices could be
different and may introduce a source of error in the
calibration model.
In addition, a full concentration range of the target
element(s) of interest is needed to generate a
representative calibration curve. The highest and
lowest SSCS samples will be used to determine the
linear calibration range. Samples used to generate
the calibration curve must be prepared in a fashion
similar to samples analyzed by the XRF. Samples
used for the calibration, especially those samples at
approximately the level of concern, are used as QC
check samples during field activities.
The more the sampler knows about how the matrix
varies at the site, the more representative the
calibration model, and the more accurate the
results. A minimum of 10 samples are
recommended to generate the calibration; the
maximum number is 30. A general rule is to add 5
samples for each element of interest and 5 samples
for each adjacent element. As the number of
elements under analysis increases, more calibration
samples are required to adequately characterize the
concentration ranges present for each element. Be
aware that there may be a need for more than one
calibration model to maintain linearity over the
concentration ranges in question.
2.7.2 In Situ Soli Analysis
In situ soil measurements provide a rapid means of
data collection at a large number of sample points,
eliminate the need for sample containers and chain
of custody forms, and yield real-time measurements.
Two primary scenarios exist for in situ
measurements. First, perform rough, rapid, non-
quantitative XRF screening with a non-site-specific
or generic calibration model; this allows for
decisions such as where to collect samples for use in
a site-specific calibration model. This scenario
takes into account previous data collected at the
site, a visual inspection of the site, and historical
background information. Care should be exercised
when using non-site-specific or generic calibration
models, as variations in sample representativeness
and matrices may significantly limit the validity of
the model Second, in situ XRF screening is
conducted with a site-specific calibration model
providing rapid, semi-quantitative data.
In addition to these two in situ scenarios, XRF
analysis may be performed on samples which have
been collected and undergo some type of sample
preparation. When sampling is employed, the
prepared sample is analyzed by XRF measurement,
and the same portion is then submitted for
confirmation analysis by AA/ICP, according to
QA/QC protocols. A split portion of the sample is
archived.
Remove all surface debris in the sampling location.
To avoid cross contamination, place a single
thickness plastic sample bag or polypropylene film
over the probe and firmly press the probe to the
ground. Where possible, maximize instrument
performance by placing it 3 mm from the ground
surface. It should be noted that in situ
measurements can exhibit a high degree of
variability due to the natural heterogeneity of the
soil. This effect may be minimized by averaging
multiple readings within a predetermined area
based on sampling objectives. Single in situ
measurements may be used at any one sample
location; however, this can reduce the precision and
representativeness associated with the XRF results.
Therefore, the minimum recommended
measurement time or duration for in situ analysis is
30 seconds. All sample readings should be
recorded.
The depth of X-ray penetration for analysis is only
the first two or three millimeters of soil. Therefore,
in situ measurements represent data from the
ground surface only, and in no way reflect sub-
surface soil conditions. As little as 0.5 cm of clean
soil cover can completely mask a hot spot. Also, in
situ analysis can have a high degree of error due to
the heterogeneity and possible wide range of
particle size fractions present in the sample. Data
obtained from in situ analysis is best suited for site
characterization activities where the user is
interested in obtaining a quick overview of site
conditions at the surface. It can also define extent
of contamination if confirmation samples are used.
2.7.3 Soil Samples for XRF Analysis
Discrete sample collection involves physical
collection of a soil sample (4 oz.) and some type of
field preparation prior to XRF analysis. Two types
of discrete XRF sampling are utilized in the field.
One type involves collecting a sample in a plastic
bag, rough sieving it to remove organic debris and
rocks, and homogenizing it by mixing in the bag.
9
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Take the XRF reading by directly measuring
through the sample bag. Take three measurements
from each bag, shaking the bag between
measurements. A measurement time of 15-30
seconds is recommended. Be consistent with
sampling time for all samples collected. Once XRF
measurements are complete, prepare a minimum of
10% of the samples for confirmation analysis by
AA/1CP. It is imperative that the same sample
utilized for XRF analysis be sent for the
confirmation analysis; this is typically accomplished
by splitting the volume of the original sample
prepared, one half being sent for analysis to the lab
and one half being archived.
A second method of discrete XRF sampling involves
a more rigorous method of sample preparation.
The first step in sample preparation is drying, either
by air, in a conventional oven at 105ฐC, or with a
moisture balance. Drying is a recommended step
and is necessary based on moisture content of the
soil. Use care when using a microwave oven or
conventional oven for drying due to their potential
to vaporize lead, arsenic and mercury, if present in
samples. Not only does this lead to error, but it
may be a health hazard. Small, air-circulating or
moisture balance ovens are recommended. Proper
respiratory protection should be worn.
Once dry, remove any visible organic debris and
sieve the sample through a 20-mesh sieve. Fill a
sample cup with the prepared sample and retain it
for confirmation analysis. Settle contents in the
sample cup by tapping; this will yield a more
smooth, uniform surface for analysis. Cover the
sample with polypropylene film (making certain
there are no wrinkles in the film) and analyze it for
240 seconds. Shake the cup and analyze again.
Repeat this procedure for a total of three readings
on each sample. Record the individual results and
calculate an average. Save the prepared sample
cup. A minimum of 10% of the prepared sample
cups should be sent for confirmational analysis by
AA/ICP procedures.
2.8 CALCULATIONS
Mathematically model the matrix calibration for
optimum linearity, as per the XRF operating
instructions.
2.9 QUALITY ASSURANCE/
QUALITY CONTROL
There are a number of QA/QC measurements
which must be utilized when performing XRF
analysis.
Precision is determined by repeated
measurements of a low matrix calibration
standard at the he-ginning of sampling
activities, and then after every tenth
sample. This sample is analyzed for the
same time as the field samples. The
precision objective for XRF should be
ฑ20% relative standard deviation. A mid-
range matrix calibration sample is also
recommended to aid in determining
instrument precision. This sample should
be at or near the concentration level of
interest. By running low-level calibration
samples, gain changes and baseline drift
can be monitored.
Accuracy is best determined by 'icing site-
specific, low-, mid- and high-level
calibration samples that are analyzed by
AA/ICP.
Representativeness is best determined by
developing an adequate sampling scheme
which characterizes the range of
contaminants and matrix variability at the
site. When the calibration samples
accurately characterize the range of
contaminant concentrations on site, the
calibration model will be representative of
the site.
The question of comparability arises when
XRF data are compared to AA or ICP
data obtained from a sample digestion
procedure. XRF data may not be
comparable to data obtained by AA or
ICP. The portable XRF should be used as
a screening tool in conjunction with these
more rigorous analytical methods,
especially with the acid digestion method
procedures. Using AA/ICP, samples
should be prepared in the same manner as
those for XRF analysis.
Completeness is determined on a site-
specific basis and is a measure of the
desired number of samples analyzed versus
the actual number of samples analyzed.
10
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Replicates are recommended at a
minimum rate of 5-10%. Replicate
samples should be prepared independently
of other samples and go through the same
sample preparation procedure. Replicates
are a check on homogeneity of the sample
matrix, consistency of sample preparation,
and precision of the analysis.
Confirmation samples are recommended
at a minimum rate of 10%. Ideally, the
sample that was analyzed by XRF should
be the same sample that is sent for
AA/ICP confirmation analysis. When
confirming an in situ analysis, collect a
sample from a six-inch by six-inch area for
both an XRF measurement and a
confirmation analysis. The correlation
factor between XRF and AA/ICP data
should be 0.7 or greater.
Performance evaluation (PE) samples are
another possible QC mechanism for
checking AA/ICP analysis, but are not
typically applicable to XRF analysis due to
a dissimilar matrix. If the site matrix does
not match the PE matrix, the user should
not utilize the PE samples.
1.10 DATA VALIDATION
This section is not applicable to this SOP.
1.11 HEALTH AND SAFETY
When working with potentially hazardous materials,
follow U.S. EPA, OSHA, and site-specific health
and safety procedures.
11
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12
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3.0 PHOTOIONIZATION DETECTOR (HNU): SOP #2056
3.1 SCOPE AND APPLICATION
This Standard Operating Procedure (SOP) describes
the procedure for using a pbotoionization detector
(PID). The PID is a portable, non-specific,
vapor/gas detector employing the principle of
photoionization to detect a variety of chemical
compounds, both organic and inorganic, in air. This
procedure is applicable to the HNU-PI 101.
3.2 METHOD SUMMARY
The PID is a useful general survey instrument at
hazardous waste sites. A PID detects and measures
real-time concentrations of many organic and
inorganic vapors in air. A PID is similar to a flame
ionization detector (FID) in application; however,
the PID has somewhat broader capabilities as it can
detect certain inorganic vapors. Conversely, the
PID is unable to respond to certain low molecular
weight hydrocarbons, such as methane and ethane,
which are readily detected by FID instruments.
The PID employs the principal of photoionization.
The analyzer responds to most vapors with an
ionization potential less than, or equal to, that
supplied by the detector, which is an ultraviolet
(UV) lamp. Photoionization occurs when an atom
or molecule absorbs a photon of sufficient energy to
release an electron and form a positive ion. This
action occurs when the ionization potential of the
molecule in electron volts (eV) is less than the
energy of the photon. The sensor is housed in a
probe and consists of a sealed ultraviolet light
source that emits photons with an energy level high
enough to ionize many trace organics, but not
enough to ionize the major components of air. A
chamber exposed to the light source contains a pair
of electrodes, one bias electrode and one collector
electrode. When a positive potential is applied to
the bias electrode, a field is created in the chamber.
Ions formed by the adsorption of photons are driven
to the collector electrode. The current produced is
then measured and the corresponding concentration
is directly displayed on a meter in units above
background. Several probes are available for the
PID, each having a different source and a different
ionization potential The selection of the
appropriate probe is essential to obtain useful field
results. Though it can be calibrated to a particular
compound, the instrument cannot distinguish
between detectable compounds in a mixture of
gases, and therefore produces an integrated
response to the mixture.
Three probes, each containing a different UV light
source, can be used with the HNU. Energies are
9.5, 10.2, and 11.7 electron volts (eV). All three
detect many aromatic and large molecule
hydrocarbons. In addition, the 10.2 eV and 11.7 eV
probes detect some smaller organic molecules and
some halogenated hydrocarbons. The 102 eV
probe is the most useful for environmental response
work, as it is more durable than the 11.7 eV probe
and detects more compounds than the 9.5 eV probe.
Gases with ionization potentials near to, or less
than, that of the lamp will be ionized, and thus be
detected and measured by the analyzer. Gases with
an ionization potential higher than that of the lamp
will not be detected. The ionization potentials for
various atoms, molecules, and compounds are given
in Appendix B. The ionization potential of the
major components of air (oxygen, nitrogen, and
carbon dioxide) range from about 12.0 eV to about
15.6 eV, so are not ionized by any of the three
lamps.
Ionization sensitivity for a number of chemical
groupings when exposed to photons from a 10.2 eV
lamp is illustrated in Table 2. Applications of each
probe are included in Table 3.
While the HNU is primarily used as a quantitative
instrument, it can also be used to detect certain
contaminants, or at least narrow the range of
possibilities. Noting instrument response to a
contaminant source with different probes eliminates
some contaminants from consideration. For
instance, a compound's ionization potential may be
such that the 9.5 eV probe produces no response,
but the 10.2 eV and 11.7 eV probes do elicit a
response.
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Table 2: Relative Photoionization Sensitivities for Various Gases
Chemical Group
Relative
Sensitivity
Examples
Aromatic
10
benzene, toluene, styrene
Aliphatic Amine
10
diethylamine
Chlorinated Unsaturated
5-9
vinyl chloride, vinylidene chloride, trichloroethylene
Carbonyl
5-7
MEK, MIBK, acetone, cyclohexanone
Unsaturated
3-5
acrolein, propylene, cyclohexanone, allyl alcohol
Sulfide
3-5
hydrogen sulfide, methyl mercaptan
Paraffin (C5-C7)
1-3
pentane, hexane, heptane
Ammonia
03
Paraffin (Cj-C^)
0
methane, ethane
Note: Relative sensitivity is the actual HNU meter reading observed when measuring a 10 ppm gas
concentration of the listed chemical, using the 10.2 eV probe (calibrated for 10 ppm of benzene) and
a span setting of 9.8 (for direct reading of benzene).
3.3 SAMPLE PRESERVATION,
CONTAINERS, HANDLING, AND
STORAGE
This section is not applicable to this SOP.
3.4 INTERFERENCES AND
POTENTIAL PROBLEMS
3.4.1 PID Instrument Limitations
The PID is a non-specific, total vapor
detector. It cannot be used to identify
unknown substances; it can only quantify
them.
The PID must be calibrated to respond to
benzene using isobutylene calibration gas
which has been analyzed and compared to
a known benzene standard.
The PID does not respond to certain low
molecular weight hydrocarbons, such as
methane and ethane, and does not detect a
compound if the probe has a lower energy
than the compound's ionization potential.
Methane absorbs ultraviolet lamp energy.
One-half percent methane will result in a
30 percent reduction in detector sensitivity
and 5 percent methane will yield a 90
percent decrease in detector sensitivity.
Certain toxic gases and vapors, such as
carbon tetrachloride and hydrogen cyanide,
have high ionization potentials and cannot
be detected with a PID.
Certain models of PID instruments are not
intrinsically safe. The HNU-PI 101 PID is
not designed for continuous use in
potentially flammable or combustible
atmospheres. Therefore, a PID should be
used in conjunction with a Combustible
Gas Indicator.
14
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Table 3: Typical Applications of Interchangeable Probes
Compound
Ionization Potential
(eV)
Relative Sensitivity
p-xylene
8.44
0.10
0.104
p-chlorotoluene
8.70
0.09
0.112
toluene
8.82
0.09
0.112
o-chlorotoluene
8.83
0.075
0.112
ethyl acetate
9.19
0.075
0.112
benzene
9.24
0.10
0.10
methyl mercaptan
9.24
0.10
0.072
pyridine
932
0.075
0.122
allyl alcohol
9.67
0.10
0.112
crotonaldehyde
9.88
0.075
0.104
amyl alcohol
9.80
0.09
0.116
cyclohexane
9.88
0.075
0.104
vinyl chloride
9.95
0.085
0.112
butanol
10.94
0.09
0.176
ammonia
10.15
0.06
0.160
acetic acid
1037
0.04
0.560
ethylene
10.52
0.0
0320
ethylene oxide
10.56
0.0
0.298
Note: Relative sensitivity equals the response with the 9.5 eV probe or the 11.7 eV probe divided by the
response with the 10.2 eV probe.
Electrical power lines, radiotransmissions
or power transformers may cause
interference with the instrument and thus
cause measurement errors.
* Winds and high humidity will affect
measurement readings. The HNU may
become unusable under foggy or humid
conditions, when condensation occurs on
the lamp. This is indicated by the needle
dropping below zero, or a slow constant
climb on the read-out dial.
The lamp window must be periodically
cleaned to ensure the maximum
transmission of the ionizing protons into
the detector chamber.
* The 11.7 eV lamp window is a type of
fluoride crystal which is hygroscopic and
15
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will absorb water vapor from the sample
stream. In high humidity applications, the
lamp should be cleaned with an oil-free,
dilorinated hydrocarbon, or freon on a
daily basis.
The HNU measures concentrations from
about 1-2000 ppm, although the response is
not linear over this entire range. For
example, the response to benzene is linear
from about 0-600 units above background.
This means the HNU reads a true
concentration of benzene only between 0
and 600. Greater concentrations are
detected at a lower level than the true
value.
Do not use this instrument for head space
analysis where liquids can inadvertently be
drawn into the probe.
3.4.2 Regulatory Limitations
Transport of calibration gas cylinders by
passenger and cargo aircraft must comply
with the U.S. Code of Federal Regulations,
49 CFR Parts 100-177. A typical
calibration gas included with a PID is
isobutylene. It is classified as a non-
flammable gas, UN #1556 and the proper
shipping name is Compressed Gas. It must
be shipped by cargo aircraft only.
3.5 EQUIPMENT/APPARATUS
PID (HNU)
operating manual
probes: 9.5 eV, 10.2 eV, or 11.7 eV
battery charger for PID
spare batteries
jeweler's screwdriver for adjustments
Tygon tubing
NBS traceable calibration gas (type)
"T" valve for calibration
field data forms
intake assembly extension
strap for carrying PID
Teflon tubing for downhole measurements
plastic bags for protecting the PID from
moisture and dirt
Note: This instrument may be kept on continuous
charge without battery damage.
3.6 REAGENTS
* isobutylene standards for calibration
* methanol for cleaning ionization chamber
(GC grade)
* mild soap solution for cleaning unit
surfaces
* specific gas standards when calibrating to a
specific compound
* light source cleaning compound Cat No.
PA101534-A1 (for 9.5 and 10.2 eV lamps
only)
* oil-free, chlorinated solvent, or freon for
cleaning the 11.7 eV lamp
The HNU is calibrated according to the operations
manual, using isobutylene as the calibration
standard. Also, refer to the operations manual for
alternate calibration to a specific compound.
Current HNU manuals contain an error with the
isobutylene response factor for the 10.2 eV lamp.
The manual indicates 7.0 whereas the correct value
is approximately 5.5.
3.7 PROCEDURES
3.7.1 Start-up
1. Check to ensure the proper operation of the
PID, as appropriate, using the equipment
checklist provided in Sections 3.5 and 3.6 and
the steps listed below.
2. Allow the temperature of the unit to equilibrate
to its surrounding (about 5 minutes).
3. Attach the probe to the read out unit. Match
the alignment key, then twist the connector
clockwise until a distinct locking is felt.
4. Turn the Function switch to the battery check
position. Check to ensure that the indicator
reads within or beyond the green battery arc on
the scale plate. If the indicator is below the
green arc, or if the red LED comes on, the
battery must be charged prior to using.
16
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5. To zero the instrument, turn the Function
switch to the Standby position and rotate the
Zero Potentiometer until the meter reads zero.
Wait 15-20 seconds to ensure that the zero
adjustment is stable. If not, then readjust.
6. Check to see that the Span Potentiometer is set
at the appropriate setting for the probe being
used.
7. Set the Function switch to the desired range.
8. Listen for the fan operation to verify fan
function.
9. Look for ultraviolet light source in the probe to
verify function. Do not look at this light source
from closer than 6 inches with unprotected
eyes; observe briefly.
10. Prior to survey, check instrument with an
organic point source such as a Magic Marker to
verify instrument function.
11. Routinely throughout the day, verify the
remaining useful battery life by turning the
Function switch to BATT. Schedule the
instrument's use accordingly.
3.7.2 Field Operation
Field Calibration
1. Follow the startup procedure in Section 3.7.1.
2. If the PID does not start up, check out, or
calibrate properly, the instrument should not be
used. Under no circumstances should work
requiring PID air monitoring be done without
a properly functioning instrument.
3. Set the Function switch to the range setting for
the concentration of the calibration gas.
4. Attach a regulator to a disposable cylinder of
calibration gas. Connect the regulator to the
probe of the HNU with a piece of clean Tygon
tubing. Open the valve on the regulator.
5. The latest technical information from HNU is
that the external Span Adjustment Control
should be used to calibrate the instrument.
That is, if you are calibrating an HNU to a 60
ppm isobutylene as benzene standard with the
unit set at 9.8, and the HNU reads 50 ppm, the
external Span Adjustment Control should be
adjusted to a lower number setting until the
correct reading has been obtained. The lower
the number on the Span Adjustment Control
the greater the instrument sensitivity.
6. Record the following information in the site
logbook: the instrument ID number (EPA
decal or serial number if the instrument is a
rental), the initial and final span settings, the
date and time, concentration and type of
calibration gas used, and the name of the
person who calibrated the instrument.
7. Record the calibration data in the field.
8. In some field applications, with the exception of
the probe's inlet and exhaust, the PID should
be wrapped in clear plastic to prevent it from
becoming contaminated and to prevent water
from getting inside in the event of precipitation.
Operation
1. Record all readings in the site logbook.
Readings should be recorded as "units above
background," not ppm.
2. As with any field instrument, accurate results
depend on the operator being completely
familiar with the operator's manual. In order
to obtain accurate results, follow the
instructions in the operating manual explicitly.
3. Position the probe assembly close to the area
to be monitored because the low sampling rate
allows for only very localized readings. Under
no circumstances should the probe tip assembly
be immersed in fluid.
4. While taking care not to expose the PID to
excessive moisture, dirt, or contamination,
monitor the work activity as specified in the site
health and safety plan. Conduct the PID
survey at a slow to moderate rate and the
intake assembly (the probe) should slowly
sweep from side to side. There is a 3 to 5
17
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second delay in read-out, depending upon the
instrument's sensitivity to the contaminant.
5. During drilling activities, perform PID
monitoring at regular intervals downhole, at the
headspace, and in the breathing zone. In cases
with elevated organic vapor levels, monitor in
the breathing zone during actual drilling. When
the activity being monitored is not drilling,
readings should emphasize breathing zone
conditions.
6. When the activity is completed, or at the end of
the day, carefully clean the outside of the PID
with a damp disposable towel to remove any
visible dirt. Check calibration again before
storing. Return the PID to a secure area and
place on charge.
3.7.3 Post Operation
1. Turn Function switch to "off."
2. Place the instrument on the charger. When on
charge, the probe must be connected to the
readout unit to ensure charging.
3. Complete logbook entries, verify the accuracy
of entries, and sign/initial all pages. Following
completion of a series of "0" readings, verify the
instrument is working.
4. Check the equipment, repair or replace
damaged equipment, and charge the batteries.
3.8 CALCULATIONS
The HNU is a direct reading instrument. Readings
are interpreted as units above background, rather
than ppm.
3.9 QUALITY ASSURANCE/
QUALITY CONTROL
There are no specific quality assurance activities
which apply to the implementation of these
procedures. However, the following QA procedures
apply:
All data must be documented on field data
sheets or within site logbooks.
All instrumentation must be operated in
accordance with operating instructions as
supplied by the manufacturer, unless
otherwise specified in the work plan.
Equipment checkout and calibration
activities must occur prior to
sampling/operation, and must be
documented.
3.10 DATA VALIDATION
This section is not applicable to this SOP.
3.11 HEALTH AND SAFETY
When working with potentially hazardous materials,
follow U.S. EPA, OSHA, and site-specific health
and safety practices.
The HNU-PI 101 is certified for use in Class 1,
Division 2, Groups A, B, C, and D.
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4.0 PHOTOVAC 10A10 PORTABLE GAS CHROMATOGRAPH
OPERATION: SOP #2107
4.1 SCOPE AND APPLICATION
This Standard Operating Procedure (SOP) describes
the use, calibration, and maintenance of the
Photovac 10A10 portable gas chromatograph. The
Photovac 10A10 gas chromatograph is used for Held
and laboratory analysis of air, soil gas, and
water/soil headspace samples. Chlorinated and
non-chlorinated alkenes and aromatic hydrocarbons
down to the 1 to 20 part per billion (ppb) range can
be detected.
4.2 METHOD SUMMARY
The Photovac 1QA10 is a battery/AC-operated
photoionization detector (PID) portable gas
chromatograph. It is a field instrument capable of
monitoring for many organic vapors using an
ultraviolet light source and a photoionization
detector. The samples are introduced into the
10A10 via gas-tight syringes. Gaseous contaminants
are ionized as they emerge from the column. The
ions are then attracted to an oppositely charged
electrode, which causes a current and sends an
electronic signal to a strip chart recorder or,
alternately, to an integrator/plotter system.
4.3 SAMPLE PRESERVATION,
CONTAINERS, HANDLING, AND
STORAGE
This section is not applicable to this SOP.
4.4 INTERFERENCES AND
POTENTIAL PROBLEMS
This instrument should not be exposed to
precipitation or high humidity.
The instrument works best in a stable,
temperature-controlled environment.
Liquids should not be injected into this
instrument.
Readings can only be reported relative to
retention times of the calibration standard
used.
Combustion fumes can contaminate the
columns.
" High concentrations of short chain alkanes
and alkenes in samples may interfere with
the resolution and detector sensitivity of
early-eluting chlorinated alkenes, and
aromatic compounds.
Since the Photovac is a GC, the target
compounds are identified by their retention
times (RTs). If the RT of the sample
peak(s) matches the RT of the standard
peak(s), they are assumed to be identical.
If any non-target compound has the same
RT, it can be misidentified as a target
compound.
4.5 EQUIPMENT/APPARATUS
Photovac 1QA10 gas chromatograph, with
manual and power cord
extra source lamp
Photovac lamp tuning screwdriver
extra columns/fittings
ultrazero air carrier gas
two-stage regulator, with quick-connect
fitting
1 flowmeter per Photovac, either bubble-
meter, rotameter, or Gilibrator
septa, 6 mm diameter
syringes, gas-tight, 10 /jL to 1 mL
VOA vials filled with activated charcoal,
for syringe cleaning
integrator or strip-chart recorder, with
appropriate connections
labels
extra Photovac integrator pens
extra Photovac integrator paper
tools -- large adjustable wrench, wrenches
(5/16 inch to 9/16 inch), screwdrivers (flat
and Phillips head), needle-nose pliers,
jeweler's screwdrivers, Allen wrenches
duct tape
19
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Teflon tape
power strip
snoop
Kim wipes (or similar lint/static free wipe)
Pelican cases (or equivalent)
4.6 REAGENTS
carrier gas cylinder (compressed ultrazero
air, 0.1 ppm total hydrocarbons).
headspace calibration standards (Supelco A
and B or equivalent).
certified gas calibration standards with a ฑ
2% level of accuracy (from Scott Speciality
Gas, Matheson Gas, or other reliable
source).
4.7 PROCEDURES
4.7.1 Laboratory Operation
1. Attach the carrier gas (air) cylinder to the
1QA10, and, via the second stage of the dual-
stage regulator, deliver a maximum of 40 psi.
2. The flow rate will vary according to the target
compounds in question and the column used.
Adjust the carrier gas flow using the knurled
knob to the left of the 10A10, labeled Column
1 or Column 2. The flow is measured by
attaching a flowmeter to the vent port at the
top left of the unit. Once the flow is set, the
PID will stabilize after approximately 1/2 hour
of warm up time. Set the output at 10 mV
using the offset knob in the center of the unit.
3. Attach an interface cable from the output lead
on the 10A10 to a strip chart recorder, or
preferably, a plotter-integrator such as the
Hewlett Packard 3396A. The voltage input
and/or attenuation is selected on the chart or
integrator to keep peaks on scale. Check that
the electrical controls are set as follows:
power switch to "ofF
charge switch to "off"
attenuation switch to 100 (lowest
sensitivity)
offset dial to zero
chart recorder connected to the coaxial
output connector
chart recorder set to 100 mV (full scale)
and chart speed to 1 cm/min
power cord plugged into the panel socket
(the red AC indicator light will come on)
The instrument is now in its power down
condition and is ready for starting.
4. With the chart recorder off, switch on the
power switch. The red Source Off indicator will
light and stay on for up to 5 minutes. During
this time the lamp-start sequence is being
automatically initiated.
5. As soon as the Source Off light is extinguished,
the meter shows a high reading which should
fall as conditions in the photoionizing chamber
stabilize.
6. Establish an acceptable base line on the chart
recorder.
The instrument is now ready for calibration.
4.7.2 Calibration
Refer to Table B, Appendix B, for the calibration
and maintenance schedule. Photovac Incorporated
conducts an instrument calibration and includes the
chromatogram as a component of that instrument's
instruction manual. A check of the instrument's
performance can be accomplished by duplicating the
factory calibration check and comparing the results.
The procedure is as follows:
1. Completely flush a clean 1-L sample bottle (or
a clean 1-L Tedlar bag fitted with a septum
cap) with good quality bottled air.
2. Using the factory calibration data sheet,
calculate the required amounts of each
calibration compound required to generate an
air standard (with a total volume of 1 liter)
which is identical to that run by Photovac in the
factory calibration.
3. Using an appropriate volume gas-tight syringe,
aspirate the required amount of each
20
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compound from the headspace of the storage
bottles at room temperature, and inject it into
the purged 1-L sample bottle (or Tedlar bag).
Be careful to fully flush the syringe with clean
air before injecting a new compound.
4. Allow 10 minutes for the standard to
equilibrate.
5. Using a clean 100 fA gas-tight syringe, aspirate
the required injection volume from the 1-L
standard. With a crisp and snappy action, inject
the standard into the proper "injection port" of
the Photovac 10A10.
6. Start and mark the strip chart recorder. The
resulting chromatogram should be similar to the
factory calibration chromatogram, under similar
conditions.
7. A simple calibration curve can be constructed
by injecting the same volume of several
standards with varying concentration levels of
the target compounds. Alternatively, a
calibration curve can also be constructed by
injecting various volumes (10 - 1000 nL) of the
same standard. In this case, the response of
the standards and samples should be
normalized to one injection volume. Both
standards and samples present in Tedlar bags
can be diluted in the Held.
4.7.3 Field Operation
1. Prior to any field analyses, check to ensure that
the instrument is operational and clean.
Remove closure fittings on the Detector Out
port. Closure fittings may have been engaged
to prevent static contamination.
2. Check that the carrier gas supply is adequate
(charge supply is 1800 PSI and should last up to
approximately 3 days, depending on carrier flow
rates).
3. Set the pressure regulator to zero (fully
counterclockwise) and turn on the main valve of
the lecture bottle.
4. Slowly turn the regulator control clockwise until
air begins to escape from the quick-disconnect
connection. Allow the line to purge for 10
seconds.
5. Plug the quick-disconnect fitting into the free
Carrier in port. Shut off and disconnect the
laboratory air supply. Adjust the lecture bottle
regulator to 40 psig. Set the required flow rate
as described previously using a bubble meter,
calibrated rotameter, or Gilibrator.
6. With the instrument in the "power down" mode,
disconnect the AC power supply. This
automatically switches the instrument to battery
power. The instrument is now completely self-
contained, and, with a battery powered
recorder, may be taken into the field. Check
the battery charge on the Photovac.
7. The instrument is now ready to be run through
the start-up procedures described under
Laboratory Operation, parts 4-8 of the manual.
8. If there is a significant change in ambient
temperature when the instrument is moved
from one place to another, the column will
require time to stabilize thermally. At higher
sensitivities, a non-thermally stabilized column
will manifest itself as baseline drift.
9. For troubleshooting information, refer to
Appendix B.
4.7.4 Shut Down
1. Turn the power switch to "off."
2. Reduce the carrier gas flow to 2-5 cm3/min.
3. Place the instrument on low charge while on
the bench and maintain it as described in Table
F and Section 4.7.6 below.
4. Unplug the unit except when charging batteries.
4.8 CALCULATIONS
4.8.1 Calibration Curve
A calibration curve of at least three concentrations
must be constructed for each target compound. A
straight line equation in the form of y = (m)(x)+b
(where: x = concentration, y = area counts, m =
slope and b = the intercept) is fit to the standards
raw data. The (y), or the unknown concentration
for the sample, is determined from the above
straight line equation. Non-linear data is indicative
21
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of detector response range limitations.
where:
Alternatively, sample concentration can be
calculated as shown below;
A. V.
[.Sample] ฐ [Std\ -l- ฆ
where:
sample = concentration of sample (ppb or
ppm)
A, = peak area of sample (volts x
seconds)
A2 = peak area of standard (volts x
seconds)
V, = injection volume of sample (uL)
V2 = injection volume of standard (#iL)
std = concentration (ppb or ppm)
4.8.2 Standard Response
Generation/Duplication of
Factory Calibration Data
If appropriate gas standard mixtures are not
available, gas standards can be made using the
headspace from 40-mL VOA bottles, with Teflon-
lined septa screw caps, partially filled with the
desired neat volatile liquid. Factory instrument
response is generally determined using the following
three compounds:
Compound
P^ @ 20ฐ C
methylene chloride
347 mm Hg
n-hexane
126 mm Hg
benzene
74 mm Hg
These compounds are toxic and should be stored
and worked with under a hood. The general
formula for preparing a standard from the
headspace above a volatile liquid is:
' HS
1VAP
C
V
volume of headspace
(mL)
vapor pressure of liquid
(mm HG)*
desired concentration
(ppm)
volume of standard vessel
(liters)
760 (Q (V)
as
* Use appropriate tables to determine compound
vapor pressure if working environment is not 2Of C.
A determined volume of neat liquid headspace may
be introduced to the standard vessel through the
septa if using a Tedlar bag is used with the
appropriate fitting. Bags or vessels used should be
labelled with content concentrations, date, and time
of preparation.
4.9 QUALITY ASSURANCE/
QUALITY CONTROL
There are no specific quality assurance activities
which apply to the operation of the Photovac.
However, all instrumentation must be operated in
accordance with operating instructions as supplied
by the manufacturer, unless otherwise specified in
the work plan. Equipment checkout and calibration
activities must occur prior to sampling or operation
and they must be documented.
4.10 DATA VALIDATION
This section is not applicable to this SOP.
4.11 HEALTH AND SAFETY
When working with potentially hazardous materials,
follow U.S. EPA, OSHA, and site-specific health
and safety practices.
22
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5.0 PHOTOVAC 10S50, 10S55, AND 10S70 GAS CHROMATOGRAPH
OPERATION: SOP #2108
5.1 SCOPE AND APPLICATION
This Standard Operating Procedure (SOP) pertains
to the use, calibration, and maintenance of the
Photovac 10S series portable gas chromatographs.
The 10S series gas chromatographs are used for
field and laboratory analysis of air, soil gas, and
water and soil headspace. It tests for chlorinated
and non-chlorinated, alkene and aromatic,
compounds with detection limits of 1-5 ppb (parts
per billion) for headspace analysis and 10-50 ppb
for soil gas analysis.
5.2 METHOD SUMMARY
The Photovac 10S series are battery/AC operated,
portable gas chromatographs with photoionization
detectors. They are field/laboratory instruments
capable of screening for many organic vapors using
an ultraviolet light source and photoionization
detector. Gaseous contaminants are ionized as they
emerge from the column. The ions are then
attracted to an oppositely charged electrode which
causes a current and sends an electronic signal to
the Photovac internal microprocessor or optional
integration device. Refer to ERT SOP #2109,
Photovac GC Analysis for Air, Soil Gas, Water, and
Soil, for additional information.
5.3 SAMPLE PRESERVATION,
CONTAINERS, HANDLING, AND
STORAGE
This section is not applicable to this SOP.
5.4 INTERFERENCES AND
POTENTIAL PROBLEMS
These instruments should not be exposed
to precipitation or high humidity.
The instruments are best utilized in stable,
temperature-controlled environments (even
when using the internal temperature-
controlled oven assembly, which may only
reduce the effect of external atmospheric
temperature variances). When used
directly in the field, it is best to maintain
constant temperatures to avoid the
fluctuating retention times which may occur
with changing temperatures.
Readings can only be reported relative to
retention times of the calibration standard
used.
Combustion fumes can contaminate the
column.
High concentrations of short chain alkanes
and alkenes in samples may interfere with
the resolution and detector sensitivity of
early-eluting chlorinated alkenes and
aromatic compounds.
Since the Photovac is a GC, the target
compounds are identified by their retention
times (RTs). If the RT of the sample
peak(s) matches the RT of the standard
peak(s), they are assumed to be identical.
If any non-target compound has the same
RT, it can be misidentifled as a target
compound.
5.5 EQUIPMENT/APPARATUS
5.5.1 Equipment List
Photovac 10S series gas chromatograph,
with manual and power cord
extra source lamp
Photovac lamp tuning screwdriver
extra columns/fittings
ultrazero air carrier gas
two-stage regulator, with quick-connect
fitting
one flowmeter per Photovac, either bubble-
meter, rotameter, or Gilibrator
septa, 6-mm diameter
syringes, gas-tight, 10-/iL to 1-mL
VOA vials filled with activated charcoal,
for syringe cleaning
extra Photovac integrator pens
23
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extra Photovac integrator paper
labels
tools -- large adjustable wrench, wrenches
(5/16 inch to 9/16 inch), screwdrivers (flat
head and Phillips head), needle-nose pliers,
jeweler's screwdrivers, Allen wrenches
duct tape
Teflon tape
power strip
snoop
Kim wipes (or similar lint/static free wipes)
Pelican cases
5.5.2 Carrier Gas Supply System
Options
In most applications, the carrier gas used is ultra-
zero compressed air (<0.1 ppm THC).
Use of the Internal Reservoir as Carrier
Gas Supply
To recharge the internal reservoir, a special
(optional) device known as the High Pressure
Filling Station is needed. This device consists of the
high pressure connection (normally male, left-hand
thread) for cylinder attachment followed by a two-
way valve. The two-way valve can be positioned to
deliver gas from the cylinder to a long flexible hose
and then to the Refill receptacle located on the rear
right of the 10S50 panel. Alternatively, the valve
can be turned to release high pressure gas held in
the hose, after filling. A pressure relief valve is
provided for safety at the upper end of the flexible
hose. This is set at 1700 psi. A flow restricter is
also incorporated in line with the hose, to limit the
escape rate of gas. Under no circumstances should
the high pressure filling station be modified or
disassembled by the user. In the event of any
problems, the unit must be returned to Photovac for
repair or replacement.
Filling procedure is as follows:
1. Attach the high pressure fitting to the gas
cylinder and turn the valve handle so that it
points away from the cylinder.
2. Open the cylinder valve and check for leaks.
3. Now turn the filling station valve so that it
points toward the cylinder. A steady flow of
gas will be heard escaping from the end of the
flexible hose; this purges the hose of any
impurities.
4. Return the filling station valve to its previous
position.
5. Place the Photovac on a sturdy, flat surface
within easy reach of the flexible receptacle;
press in firmly until a click is heard.
6. Turn the filling station valve until it again
points toward the cylinder and carefully watch
the Contents gauge on the Photovac as the
needle climbs.
7. As the needle reaches approximately 1600 psi,
the pressure relief valve on the high pressure
filling station should prevent further increase.
The pressure indicated on the Contents gauge
must not exceed 1800 psi; switch the pressure
relief valve before this occurs. Switching the
valve allows high pressure gas trapped in the
flexible hose to escape, while a check valve in
the Photovac prevents the reservoir contents
from escaping.
8. Alter relieving the pressure in the hose, it can
be removed from the Refill receptacle by
pulling upward on the knurled collar and
extracting the fitting.
Use of External Tank for Carrier Gas
Supply
Whenever possible, connect the Photovac to an
external air cylinder to ensure a longer, more stable
carrier gas supply. A high quality, two-stage
regulator with output at 40 psi is required.
Connection between this regulator and the Photovac
is made using 1/8-inch Teflon tubing with a male
quick-connect fitting attached to one end.
5.6 REAGENTS
carrier gas, ultrazero air (<0.1 ppm total
hydrocarbons)
appropriate calibration standards (gas or
liquid)
24
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5.7 PROCEDURES
5.7.1 Shipping
The Photovac is initially shipped to the user in a
cardboard box provided by Photovac International.
Repeated shipping of Photovacs to field locations
(in these boxes) has resulted in occasional electrical
and mechanical problems. Shipping Photovacs in a
more rugged container, such as the Pelican King
Size Case (Orr Safety Equipment Co.), or
equivalent is recommended. The Photovac can be
left in this case while in use to prevent static
electricity and to provide thermal stability.
5.7.2 Pre-Operational Checkout
1. Check the instrument for any obvious damage.
Plug the power cord into an AC power source,
if available. Remove any closure fittings which
may have been affixed to the Detector Out, Aux
Out, and Cat Out ports in order to minimize
contamination.
2. Raise the computer module. Check that all
compression fittings associated with the
columns (the pre-column and analytical
column) and all valves which are subject to
carrier gas flow, are finger tight. Do not over-
tighten. Fittings may loosen in transit. Check
which injection port is connected to the
columns (only one may be used at a time).
Normally, the Photovac is supplied with an SE-
30, 5% packed, 6-inch pre-column and 4-feet of
analytical column unless otherwise specified
(see Figure 1, Appendix B). If a capillary
column (usually CP SiI-5, blue, equivalent to
the properties of the SE-30) with oven
temperature control module is being used,
make sure the oven ribbon connection is tight.
Attach the external 12V battery with adapter to
the BNC connector (labeled ext DC) on the left
side of the Photovac top panel. Adjust the
oven module temperature to at least 5ฐ greater
(usually _> 40ฐC) than internal operating
temperature. Close the computer module.
Allow at least 40 minutes for oven temperature
stabilization.
3. Check that the septum is new. Make sure the
septum retainer is tight. Do not overtighten.
4. Engage the carrier gas flow (ultrazero air).
Carrier gas can be introduced either by
connecting em external low pressure source
(attached by a Quick-Connect to the External
Carrier In receptacle) or by recharging the
Photovac internal high pressure refill
attachment. If operating from an external
cylinder, a clean, GC grade, two-stage regulator
should be used. Set delivery pressure to a
maximum of 40 psi. One-eighth inch Teflon
lines, brass or stainless steel swagelock fittings
and a quick-connect are used to attach the
external carrier gas to the Photovac GC. Lines
are purged 5-10 seconds with ultrazero air
carrier gas before connection to the Photovac
External Carrier gas inlet.
5.7.3 Carrier Gas Flow Rate
Adjustment
1. Set carrier gas flow rates by attaching
appropriate flow rate indicators (calibrated
rotameters, Gilibrators, bubble meters, etc.) to
the Detector Out port (red dial) and adjusting
the appropriate needle valves to give a flow of
40-50 cm3/min for a packed column and 10-15
cm3/min for a capillary column.
2. After flow rate through the detector is set, turn
on the instrument to warm it up while fine
tuning the desired flow rates. For at least one
hour prior to use, purge the instrument
(column/valving/detectors) of residual
contamination encountered in transit by carrier
gas flow.
5.7.4 Photovac Settings
1. Press to turn on the instrument.
"Lamp not ready" appears on the LCD. It
takes approximately 1-2 minutes for the lamp
to light. Do not allow more than 3 minutes for
the lamp to light, or electronic problems can
occur.
2. To enter the date and time, press
-------
to enter the ID of the compound in the library
you wish to edit, and the ID# as stated on the
printout. Press , then .
That compound is then removed from the
library. Repeat the edit sequence until all
undesired compounds have been removed from
the library selected for use.
4. Whenever the Photovac is turned off and then
on, it reverts to the default gain setting of 2. A
gain setting of at least 50 is necessary for
detection of most common pollutants (i.e.,
aromatics and chlorinated alkenes) down to a 5-
20 ppb range using a 100-250 sample
injection volume. Since this is a non-destructive
detector, small sample injection volumes are
desirable to minimize analyst exposure. Aside
from safety factors, injection volumes greater
than 1 mL are not recommended due to
column and detection volume capacity. Peak
resolution and quantitation may be distorted by
large injection volumes. To adjust the gain
setting, press < GAIN > in the Set Up section of
the Photovac top panel. Increase the gain
setting to 50 by depressing the up arrow key.
When "SO" appears on the LCD, press
< ENTER >. Perform a pre-operational
checkout (Section 5.7.2) to fine tune carrier
flow, if necessary. Otherwise, proceed with
instrument settings.
5. To set the chart recorder, press .
Using arrow keys, obtain LCD readout "Chart
Recorder on with Baseline." Press < ENTER >.
The baseline mode is recommended because it
allows the operator to observe integration
parameters and make adjustments when
necessary. "Speed? cm/min" appears on the
LCD. Use arrow keys to obtain 0.5 cm/min on
the LCD, and press < ENTER >.
6. To enter peak integration parameters, press
. When prompted by the LCD, using
the arrow keys and < ENTER > adjust settings
to:
UPSLOPE: 18
DOWNSLOPE: 14
PW @ 4: 6
"Upslope" and "downslope" refer to the change
in baseline slope necessary for the integrator to
recognize a beginning and end of a peak. The
downslope is kept lower than the upslope so
the tails of peaks are fully integrated. "PW@4"
refers to the peak width in seconds at 4 min.
This value is proportionally adjusted by the
integrator for retention times other than 4
minutes.
7. The peak window settings are pertinent only if
using the internal Photovac microprocessor's
library. Peak identification in gas
chromatography is based on retention time
(RT) matches with the standards used. When
operating at "ambient" temperature, fluctuations
in external temperature will affect compound
retention times, making peak identification
difficult and questionable. It is for this reason
that the Photovac should be operated in a
stable temperature environment. Press
, using the arrow keys and
< ENTER > to adjust the settings for the
packed column to 10 seconds and for the
capillary column to 5 seconds.
The internal microprocessor applies an
equation allowing for more extensive
fluctuations in RTs of later eluting compounds
relative to early eluting compounds, using the
window setting selected.
8. The area of rejection setting is used to
eliminate the reporting of "noise" peaks on the
report printed at the end of each run. It
designates the minimum peak area (volt -
seconds) recognized by the integration system.
A setting of 100 mVs is usually sufficient for
detection of aromatics and chlorinated alkenes
at the 5-20 ppb level at a gain setting of 50.
Press . Press the arrow keys until
100 mVs appears on the LCD. Press
.
9. Events (Manual Injection)
Manual injection operation of the Photovac
10S series with serial flow only involves
EVENT (valve actuators) 1 (a pump, with
audible sound used only for injection
timing). EVENT 1, the pump timer, is set
for a recommended maximum of 2 seconds.
26
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Press < EVENT >. When prompted by the
LCD readout, make the following entries:
ON
OFF
EVENT #
(Sec)
(Sec)
1
5
7
2
0
0
3
0
0
4
0
0
5
0
0
6
0
0
7
0
0
8
0
0
Pressing < STATUS/TEST >, then
< ENTER > produces a hard copy of the
events just entered to check for accuracy of
entries and to document analytical
procedures.
10. The Photovac GC analysis run time (length of
time peaks are recognized for integration by the
internal microprocessor) is set using the Cycle
key. Press < CYCLE >. The LCD will prompt
you for "Timer Delay (sec)." The number of
seconds entered (by the numeric keys) will be
the length of time between pressing the start
key and the start of the chart record (i.e., the
zero reference point for all peak retention
times). This value should normally coincide
with the point at which the sample is injected
(i.e., the EVENT-1 "off* time). Type "7," and
press < ENTER >.
11. "Analysis Time" will appear on the LCD
readout. Using the numeric key pad, type
"3000," and press < ENTER >. This can be
shortened later. The longest analysis time
possible with the Photovac is 3267 seconds (54
minutes).
12. "Cycle Time" appears on the LCD. Type "0" and
press < ENTER >.
13. Perform a baseline check for Photovac
operational readiness. To determine run time
progression, press the up arrow key. For
operational readiness, runs need only be 600-
700 seconds. An initial negative baseline
indicates the detector is still "warming up." An
elevated or irregular baseline, after proper flow
adjustments, indicates possible contamination
which may require additional purging time.
After a suitable baseline has been obtained, the
instrument is ready for calibration.
5.7.5 Calibration
Refer to Table B, Appendix B, for the calibration
and maintenance schedule. Photovac Incorporated
conducts an instrument calibration and includes the
chromatogram as a component of the instruction
manual. Check the instrument's performance by
duplicating the factory calibration check and
comparing the results.
1. Take a clean 1-L sample bottle or a clean 1-L
Tedlar bag fitted with a septum cap, and
completely flush with a good quality bottled air.
2. Using the factory calibration data sheet,
calculate the required amounts of each
calibration compound required to generate an
air standard (with a total volume of 1 liter)
identical to that run by Photovac in the factory
calibration. Refer to section 7.0 in the
Photovac manual (titled Calculations) if a
suitable gas standard mixture is not available.
3. Using an appropriate volume gas-tight syringe,
aspirate the required amount of each
compound from the headspace of the storage
bottles at room temperature, and inject it into
the purged 1-L sample bottle or Tedlar bag.
Be careful to fully flush the syringe with dean
air between each compound. Fill the Tedlar
bag with the factory calibration standard.
4. Allow 10 minutes for the standard to
equilibrate.
5. Using a clean 100-pL, gas-tight syringe,
aspirate the required injection volume from the
1-L standard. With a crisp, snappy action,
inject the standard into the proper "injection
port" of the Photovac.
6. Compare the chromatograph generated with
the factory-supplied "specification
chromatogram." If the difference is significant,
review the procedures and technique used in
the analysis and repeat. If results are still
unsatisfactory, call Photovac technical service.
27
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Alternate Procedures for Calibration
1. Following the start up procedure in the
instruction manual, get the Photovac on line
ready to accept a sample.
2. Obtain a gas standard mixture certified to ฑ 2%
accuracy, commercially available from
Matheson Gas Products or equivalent.
3. Using a dean, 100-^iL, gas-tight syringe,
aspirate the required injection volume from the
standard. With a crisp, snappy action, inject the
standard into the proper "injection port" of the
Photovac.
4. Compare the chromatograph generated with the
factory-supplied "specification chromatogram."
If the difference is significant, review the
procedures and technique used in the analysis
and repeat. If results are still unsatisfactory,
call Photovac technical service.
5.7.6 Shut Down
1. Press , then press < ENTER >.
2. Reset the carrier gas flow to 2-5 cm3/min.
3. Place instrument on charge while on the bench
and maintain as described in Section 5.7.7.
4. Unplug the unit except when charging batteries.
5.8 CALCULATIONS
5.8.1 Calibration Curve
A calibration curve of at least three concentrations
must be constructed for each target compound. A
straight line equation in the form of y = (m)(x) +
b, (where: x = concentration, y = area counts, m =
slope and b = the intercept) is fit to the standards'
raw data. The (y), or the unknown concentration
for the sample, is determined from the above
straight line equation. Non-linear data is indicative
of detector response range limitations.
Alternatively, sample concentration can be
calculated by:
[SampU] = [Std[
*2 vi
where:
sample = concentration of sample in ppm or
Ppb
A, = peak area of sample (volts x
seconds)
A2 = peak area of standard (volts x
seconds)
V| = injection volume of sample (/iL)
V2 = injection volume of standard (/iL)
std = concentration in ppm or ppb
5.8.2 Standard Response
Generation/Duplication of
Factory Calibration Data
If appropriate gas standard mixtures are not
available, gas standards can be made using the
headspace from 40-mL VOA bottles with Teflon-
lined septa screw caps partially filled with the
desired neat volatile liquid. Generally, factory
instrument response is determined using the
following three compounds:
Compound
P^ @ 20" C
methylene chloride
347 mm Hg
n-hexane
126 mm Hg
benzene
74 mm Hg
These compounds are toxic and should be stored
and worked with under a hood. The general
formula for preparing a standard from the
headspace above a volatile liquid is:
_ 760 (C) (V)
BS ~ p
1X9
where:
VHS = volume of headspace (^L)
Pvap = vapor pressure of liquid (mm
HG)*
C = desired concentration (ppm)
28
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V = volume of standard vessel (liters)
* Use appropriate tables to determine compound
vapor pressure if working environment is not 20ฐ C.
A determined volume of neat liquid headspace may
be introduced to the standard vessel through the
septum if using a Tedlar bag with the appropriate
fitting. Bags or vessels used should be labelled with
content concentrations, date, and time of
preparation.
5.9 QUALITY ASSURANCE/
QUALITY CONTROL
There are no specific quality assurance activities
which apply to the operation of the Photovac.
However, all instrumentation must be operated in
accordance with operating instructions as supplied
by the manufacturer, unless otherwise specified in
the work plan. Equipment checkout and calibration
activities must occur prior to sampling/operation,
and they must be documented.
5.10 DATA VALIDATION
This section is not applicable to this SOP.
5.11 HEALTH AND SAFETY
When working with potentially hazardous materials,
follow U.S. EPA, OSHA, and site-specific health
and safety practices.
29
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30
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6.0 PHOTOVAC GC ANALYSIS FOR AIR, SOIL GAS, WATER,
AND SOIL: SOP #2109
6.1 SCOPE AND APPLICATION
This Standard Operating Procedure (SOP) describes
a low-cost field laboratory screening tool for
tentative identification and determination of
concentration levels of select contaminants for site
assessment and health and safety surveys.
This method describes the rapid screening of air,
soil gas, water, and soil samples using a Photovac
portable gas chromatograph (GC) model 10S series
to determine the presence of various volatile organic
compounds.
The data allows only rapid evaluation of site
conditions and is applied to, but not limited to, the
following activities: determining the extent and
degree of contamination; defining the pollutant
plume; assessing health and safety; and tentatively
identifying and quantifying pollutants. The data
should not be used for site ranking or for
enforcement, since only limited QA/QC is required,
and the reported data is qualified as "tentative."
6.2.2 Water Samples
Water samples are collected in 40-mL VOA vials
with Teflon-lined, silicone septum screw caps. A
20-mL aliquot of sample is transferred by pipette
into a second, clean VOA vial. The vial is capped,
shaken vigorously for one minute, and allowed to
stand at room temperature for at least 30 minutes
for vapor phase equilibration. An aliquot of the
water headspace is then injected into the GC using
a gas-tight syringe.
6.2.3 Soil Samples
Soil samples are also collected in VOA vials. A 5 g
aliquot of sample is weighed into a second, clean
vial. Enough reagent water is added to bring the
total volume of the soil/water extract to 20 mL.
The vial is then capped, shaken vigorously for 1
minute, and allowed to stand at room temperature
for at least 1 hour for vapor phase equilibration.
An aliquot of the soil headspace is then injected
into the GC using a gas-tight syringe.
6.2 METHOD SUMMARY
Air, soil gas, water, or soil samples can be analyzed
by the Photovac. Brief method summaries are
provided below. All methods use a Photovac 10S
series GC equipped with a 10.6 eV photoionization
detector (PID), and use external standards to
tentatively identify and quantify compounds of
interest. Refer to ERT SOP #2108, Photovac
10S50, 10SSS and 10S70 Gas Chromatograph
Operation for additional information.
6.2.1 Air and Soil Gas Samples
Ambient air or soil gas samples are collected in 1-L
Tedlar bags. An aliquot of each bag sample is
withdrawn using a gas-tight syringe and directly
injected into the GC. Vapor from selected samples
can then be absorbed onto Tenax/CMS cartridges
for confirmational GC/MS analysis.
6.3 SAMPLE PRESERVATION,
CONTAINERS, HANDLING, AND
STORAGE
6.3.1 Air and Soil Gas Samples
Air and soil gas samples are collected and stored in
1-L Tedlar gas sampling bags, using procedures
outlined in ERT SOP #2149, Soil Gas Sampling.
Samples should be kept in a cooler out of direct
light and heat. Samples should be analyzed within
48 hours of collection, preferably within 12 hours.
Alternatively, samples may be collected in SUMMA
canisters (see ERT SOP #1704, SUMMA Canister
Sampling). In this case, sample stability may extend
up to 2 months, depending upon sample matrix.
6.3.2 Water Samples
Water samples are collected, in triplicate, in 40-mL
VOA vials. One sample is analyzed by the
Photovac; the two remaining vials are used for
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confirmation analysis by another method. They are
filled completely, with no visible air bubbles.
Samples are immediately stored out of direct light,
in a cooler packed with ice from the time of
collection until analysis. Sample vials are protected
against breakage, and analyzed within seven days of
collection.
6.3.3 Soil Samples
Soil samples are collected in 40-mL VOA vials, and
stored out of direct light, in a cooler packed with
ice (see ERT SOP #2012, Soil Sampling). Sample
containers need to be protected from breakage.
6.4 INTERFERENCES AND
POTENTIAL PROBLEMS
6.4.1 All Samples
High concentrations of short chain alkanes
and alkenes in samples may interfere with
the resolution and detector sensitivity of
early-eluting chlorinated alkenes and
aromatic compounds.
Syringes may cause carryover
contamination between samples. This can
be monitored by running regular syringe
blanks and can be minimized by
decontaminating syringes properly between
samples.
Since the Photovac is a GC, the target
compounds are identified by their retention
times (RTs). If the RT of the sample
peak(s) matches the RT of the standard
peak(s), they are assumed to be identical
If any non-target compound has the same
RT, it can be misidentified as a target
compound.
6.4.2 Air and Soil Gas Samples
Samples can be contaminated by diffusion
of volatile organics through the septum
seals and the walls of the sampling bag
during shipment and storage. A field blank
(clean Tedlar bag filled with ultrazero air,
carried through sampling and handling
protocol) can serve as a check on such
contamination.
To prevent contamination by off-gassing,
use Teflon or equivalent inert fittings and
tubing in all procedures.
6.4.3 Water and Soil Samples
Liquid samples should not be directly
introduced into the GC. Direct injection of
liquids, without heated injection ports, may
result in damage to the GC.
Samples can be contaminated by diffusion
of volatile organics through the septum seal
during shipment and storage. A field
reagent blank (a clean sample container
filled with reagent water, carried through
sampling and handling protocol) can serve
as a check on such contamination.
Some of the sample will volatilize when the
vials are opened during sample
preparation. This loss is minimized by
proper sample handling.
6.5 EQUIPMENT/APPARATUS
6.5.1 Photovac Operation
Photovac 10S series gas chromatograph,
with power cord and manual
extra source lamp
Photovac lamp tuning screwdriver
extra columns/fittings
ultrazero air carrier gas
two-stage regulator, with quick-connect
fitting
one flowmeter per Photovac, either bubble-
meter, rotameter, or Gilibrator
septa, 6-mm diameter
syringes, gas-tight, 10 /iL to 1 mL
VOA vials filled with activated charcoal,
for syringe cleaning
integrator or strip-chart recorder, with
appropriate connections
extra Photovac integrator pens
extra Photovac integrator paper
labels
tools -- large adjustable wrench, wrenches
(5/16 inch to 9/16 inch), screwdrivers (flat
and Phillips head), needle-nose pliers,
jeweler's screwdrivers, Allen wrenches
duct tape
Teflon tape
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power strip
snoop
Kim wipes (or similar lint/static free wipe)
and
Pelican cases (or equivalent)
6.5.2 Soil Gas Analysis
Tedlar bags, 1 liter
SUMMA canisters for holding gas
standards
extra-large syringe, 100 mL to 500 mL, for
serial dilutions
6.5.3 Tenax/CMS Sampling
Tenax/CMS cartridges in sealed glass
ampules
culture tubes (labeled) with glass wool to
ship cartridges
cotton gloves or cloths for cartridge
handling
fitting to connect syringe to cartridge
fitting to connect cartridge to Tedlar bag
1/4-inch silicone o-rings for a tight seal
around cartridge
6.5.4 Water Headspace Analysis
headspace standards, purgeable A and B or
equivalent
1.8-mL vials for holding standards (either
screw-cap or crimp-top vials)
Pasteur pipettes for transferring standards
40-mL VOA vials (1 per sample plus extras
for standards and QA/QC requirements)
10-mL or 20-mL pipettes and pipette bulb
liquid standard syringes
surgical gloves
6.5.5 Soil Headspace Analysis
same equipment for water headspace
analysis
portable scale, accurate to ฑ 0.1 g
spatulas, or equivalent, for transferring soil
6.6 REAGENTS
6.6.1 Air Sample Analysis
gas standards certified to ฑ 2% level of
accuracy. Although there may be other
sources, gas standards are available through
Scott Specialty Gas. In-house laboratory
preparation of calibration gas standards
with confirmational GC/MS analysis is
acceptable
ultrazero air carrier gas
6.6.2 Water and Soil Sample
Analysis
reagent water -- organic-free
chromatographic grade or equivalent, free
of any contaminants which may interfere
with the detection and resolution of target
parameters
ultrazero air carrier gas
stock standard solutions - stock standard
solutions may be prepared from pure
standard materials or purchased as certified
solutions (e.g., Supelco purgeable A or B,
or equivalent). Reagents used as standards
may depend on site-specific suspected
volatile contaminants
6.7 PROCEDURES
6.7.1 Method Detection Limits
Determine the method detection limit (MDL) just
before the analysis with a serial dilution of the
standard. The MDL is the lowest concentration that
can be detected at the gain setting selected for the
analysis. MDLs depend on the type of analysis
performed and the condition of the gas
chromatograph. Because of the difference in
matrices, air and soil gas analyses usually have
MDLs an order of magnitude above headspace
analyses. Factors that can vary the sensitivity of a
Photovac from site to site are the age of the source
lamp, detector age, column condition, shipment of
GC to the site, and location of the Geld lab.
Typical MDLs for soil gas range from 10 ppb to 50
ppb, and headspace MDLs range from 1 ppb to 5
ppb.
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If sample concentrations are high, injection volumes
may be reduced to obtain on-scale response for
parameters of interest, and to avoid contamination
of the GC system. Calculate the method detection
limit for compounds not detected at reduced
injection volumes by using:
MDL
(VJ) (CJ)
where:
V,;d = lowest volume of standard headspace
injected (/iL)
CBd = concentration of standard (ppm or ppb)
V = volume of sample headspace injected (/iL)
6.7.2 Calibration
Photovac analyses are calibrated by the external
standard method using the gas standards described
in Section 6.6.1. At the beginning of the analysis, a
three-to-five point calibration curve is run to
demonstrate linear instrument response over a
specified concentration range. The development of
this method has shown the best linearity of the PID
response to be from 10 ppb to 1 ppm for air and
soil gas analysis and from 1 ppb to 100 ppb for
headspace analysis. Most PIDs will be linear above
that range but eventually, at high enough
concentrations, the PID will become saturated. The
curve is verified daily by running a calibration check
standard from the middle of the curve.
If the response of any parameter varies from the
curve by more than ฑ25%, RSD instrument
response has changed and a new calibration curve
should be run.
Air and Soil Gas Calibration
not require the large syringes needed for serial
dilution, but the calibration curve is then limited by
the sizes of the available syringes.
Water and Soil Calibration
Headspace standards can be created at selected
concentrations by adding the appropriate volumes of
stock standard into clean 40-mL VOA vials
containing 20 mL of reagent water. These volumes
(V) are calculated by using:
y = 20 mL (stock conc.)
(calibrant conc.)
From the 200-ppm purgeable A and B standards,
first prepare a 2-ppm stock solution to allow
calibration standards between 1 ppb and 10 ppb to
be prepared with the syringes listed in Section 6.5.1.
6.7.3 Operation
Air and Soil Gas Analysis
Typical columns used for this method include SE-30
(packed) and CP-Sil 19 (capillary). An example of
compound separation using CP-Sil 19, with typical
chromatographic conditions, is shown in Figure 1,
Appendix A.
1. Inject standards after every 10-15 samples or
every 6 hours, whichever is more frequent, to
bracket possible parameter RT variations.
2. If sample concentrations are high, reduce
injection volumes to obtain on-scale response.
The method detection limit (MDL) for
compounds not detected at reduced injection
volumes is calculated according to the equation
in Section 6.7.1.
Prepare the concentrations needed for calibration
by performing a serial dilution of the gas standard.
For example, add 50 mL of a 1-ppm standard and
450 mL of ultrazero air carrier gas to a new Tedlar
bag to acquire a 100-ppb calibration standard. The
100-ppb bag can then be used to make up lower
concentration standards.
Alternatively, construct a calibration curve by
varying injection volumes. By designating a 250-fjL
injection volume as the 1-ppm standard, a 100-ppb
standard is created by injecting 25 /iL of a 1-ppm
standard. This method is more convenient and does
3. Identify the compounds in the sample by
comparing the retention time of the peaks in
the sample chromatogram with those of the
peaks in the standard chromatograms. The
width of the RT windows used to make
identifications should be based on
measurements of actual RT variations of
standards which bracket a series of sample
injections. Three times the standard deviation
of a retention time can be used to calculate a
suggested window size; however, the judgment
of the analyst should be a major factor in the
interpretation of chromatograms.
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Water Sample Analysis
Soil Sample Analysis
1. Use a pipette to place a 20-mL aliquot of 1.
sample into a clean 40-mL VOA vial. Seal the
vial with a Teflon-lined septum screw cap.
2. Shake the capped vial vigorously by hand for 1
minute. Allow it to stand, inverted and 2.
undisturbed, for at least 30 minutes at ambient
temperature for vapor phase equilibration.
3. Use a gas-tight syringe to extract an aliquot of
headspace by inserting the syringe needle 3.
through the vial septum to a distance
approximately halfway between the liquid
surface and the septum's Teflon face.
4. Purge the syringe barrel three to five times by
withdrawing and expelling a volume of 4.
headspace in slight excess of the volume
anticipated to be used for analysis.
5. If sample concentrations are high, injection
volumes may be reduced to obtain on-scale
response. If sample headspace injection volume
is reduced below the volume of the aqueous
calibration standard used to establish the
method detection limit (MDL), the detection
limit for target compounds detected at the
reduced headspace volume must be determined. S.
Do this by injecting headspace aliquots at the
reduced volume into the GC, beginning with
the 10-ppb calibration standard and increasing
or decreasing standard concentrations, as
warranted, until a response for all target
compounds has been obtained. The detection
limit for parameters detected at the lower 6.
headspace injection volume is then calculated
using the equation in Section 6.7.1.
6. Identify the compounds in the sample by
comparing the RTs of the peaks in the sample
chromatogram with those in standard
chromatograms. The width of the retention
time windows used to make identifications
should be based upon measurements of actual
retention time variations of standards over the
course of a day. Three times the standard
deviation of an RT can be used to calculate a 7.
suggested window size; however, the judgment
of the analyst should be a major factor in the
interpretation of chromatograms.
Place a clean, empty, 40-mL glass vial on the
balance. Zero the balance. Using a clean
stainless steel spatula, add 5.0 g ฑ 0.1 g of soil
sample.
Using a pipette, place enough reagent water in
the vial to bring the total volume of the soil
and water to 20 mL. Seal the vial with a
Teflon-lined septum screw cap.
Shake the capped vial vigorously for 1 minute,
to promote dispersion of the soil sample and
increase surface area. Allow to stand,
undisturbed, at ambient temperature for at
least 1 hour for vapor phase equilibrium.
Use a gas-tight syringe to extract an aliquot of
headspace by inserting the syringe needle
through the vial septum to a distance
approximately halfway between the slurry
surface and the septum's Teflon face.
Although 5 g is recommended for most soil
matrices, other amounts ranging from 1 g to
10 g have also been used, depending on sample
concentrations and the consistency of the
matrix.
Purge the syringe barrel three to five times by
withdrawing and expelling a volume of
headspace in slight excess of the volume
anticipated to be used for analysis. Wipe the
syringe needle with a Kim wipe before injection
into the GC.
If sample concentrations are high, either reduce
the injection volumes or analyze less soil to
obtain on-scale response. If sample headspace
injection volume is reduced below the volume
of the aqueous calibration standard used to
establish the MDL, follow the procedure in
Section 6.7.1 to determine the MDL for target
compounds detected at the reduced headspace
volume. Alternatively, weigh out as little as 1 g,
keeping in mind that this means a 10% error if
using a portable balance accurate to ฑ 0.1 g.
Identify the parameters in the sample by
comparing the retention times (RTs) of the
peaks in the sample chromatogram with those
in standard chromatograms. The width of the
retention time windows used to make
identifications should be based on
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measurements of actual retention time
variations of standards over the course of a day.
Three times the standard deviation of an RT
can be used to calculate a suggested window
size; however, the judgment of the analyst
should be a major factor in the interpretation of
chromatograms.
6.8 CALCULATIONS
6.8.1 Air and Soil Gas Samples
Determine the concentration of individual
compounds in each sample by using;
A. V.
[Sample] => [Sfafl
where:
sample = concentration of sample in ppb or
ppm
A, = peak area of sample (volts x
seconds)
A2 = peak area of standard (volts x
seconds)
V, = injection volume of sample (jiL)
V2 = injection volume of standard (/iL)
std = concentration in ppm or ppb
6.8.2 Water Samples
Determine the concentrations of individual
compounds in the sample by using:
A. V.
~ISample] = [Std]
Ai Kj
where:
sample =
concentration of sample in ppb or
ppm
Ai =
peak area sample (volts x
seconds)
^2 =
peak area standard (volts x
seconds).
V,
injection volume of sample (/iL)
V2
injection volume of standard (/iL)
std =
concentration in ppb or ppm
This is the same as Equation 3, except the
concentration of the headspace standard is used.
6.8.3 Soil Samples
Determine the concentrations of individual
compounds in the sample by using:
[Sample] = [&d]
A2 Vl wtmr
where:
sample =
concentrations in /ig/kg (ppb)
Ai =
peak of area sample (volts x
seconds)
Aj =
peak of area standard (volts x
seconds)
v2
injection volume of standard (pL)
v,
injection volume of sample (pL)
volume of headspace (always 20
mL)
W
"tttop
weight of sample (usually 5 g)
std =
concentration in /^g/kg (ppb)
6.9 QUALITY ASSURANCE/
QUALITY CONTROL
In order to meet the QA2 data quality objectives, at
least 10% of all field samples must be confirmed by
GC/MS analysis. The following QA/QC
requirements must be followed and provided in the
data package submitted:
Chain of custody documentation;
Sample log -- date/time of sample
collection, date/time of analysis, and run
numbers;
Blanks (see Section 6.9.1);
Instrument calibration data;
Labeling of chromatograms - identify each
chromatogram clearly by analysis type (i.e.,
syringe blank, sample number, or calibrant
concentration), injection volume, run
number, date, and time;
Replicate sample analysis -- after every ten
samples to check method/analyst precision.
The RSD of the area response of any of
the compounds should be within 15%;
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Retention time/instrument response check
since compound identification is based
upon retention time matches, run a
calibration standard after every 10-15
samples;
Calculate the percent recovery (%R) of
each compound of interest from:
100
(A-B)
Spikes - soil and water samples only (see
Section 6.9.2); and
where:
Confirmational analysis for air and soil gas
(see Section 6.9.3).
6.9.1 Blanks
R = percent recovery
A = concentration of sample and spike
B = concentration of sample
S = concentration of the spike
Air and soil gas analysis - for each day of
analysis, field standards (Tedlar bags filled
with gas standards) and field blanks
(Tedlar bags filled with ultrazero air)
accompany samples through collection,
handling, and storage.
Water analysis ~ field blank; duplicate 40-
mL VOA vials completely filled with
reagent water accompany each cooler used
for sample collection, storage, and/or
shipment.
Soil analysis reagent blank; 20 mL of the
reagent water used in the soil analysis is
placed by pipette into a clean 40-mL VOA
vial, allowed to equilibrate, and analyzed
before any samples.
Syringe blanks -- syringe blanks are to be
run prior to each sample analysis. In
practice, there is no need to run syringe
blanks if the previous sample is clean.
6.9.2 Spikes
For every 20 (soil or water) samples, one
matrix spike (MS) and one matrix spike
duplicate (MSD) must be analyzed. If there
are less than 20 samples in a matrix, at
least one MS/MSD must be analyzed.
The samples spiked should have moderate
concentrations, if possible. The amount
spiked should be equivalent to the middle
of the calibration range or one to five times
the sample background concentrations,
whichever is higher.
The percent recovery (%R), should be 50-
90% for a soil matrix, and 80-120% for a
water matrix. Due to the complexity of the
soil/water/vapor equilibria, recoveries from
soil matrices are consistently below 100%.
6.9.3 Confirmatory Analysis
Depending on work plan stipulations, at least 10%
of the air and soil gas samples analyzed by this GC
method must be submitted for confirmatory
GC/MS analysis according to modified methods
TO-1 (Tenax absorbent) and TO-2 (Carbon
Molecular Sieve [CMS] absorbent). Each soil gas
sample must be absorbed on replicate Tenax/CMS
tubes. The volume absorbed on a Tenax/CMS tube
is dependent on the total concentration of the
compounds measured by the Photovac as shown
below:
Total Concentration
Sample Volume (niL)
> 10
use serial dilution
10
10-50
5
20 - 100
1
100 - 250
A range of volumes is given to account for sample
variability. The low end of the range should be
used for samples whose total concentrations are
primarily one large peak, since too large a volume
will overload the GC/MS column when that peak is
confirmed. The high end of the range should be
used for multi-peak samples.
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6.10 DATA VALIDATION
Data should be reviewed to ensure that the QA/QC
requirements listed above have been met.
6.11 HEALTH AND SAFETY
When working with potentially hazardous materials,
follow U.S. EPA, OSHA, and corporate health and
safety practices. More specifically, the samples
should be stored in a cooler away from the analysis
area, if possible. The analysis area should have
adequate ventilation.
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7.0 MICROMONITOR M200: SOP #2111
7.1 SCOPE AND APPLICATION
This Standard Operating Procedure (SOP) presents
an overview of the Micromonitor M200 dual-
channel microchip gas chromatograph (GC),
including analytical capabilities, operating methods
and technical limitations. This microchip gas
chromatograph, complete with high resolution
capillary columns, is linked to a Macintosh personal
computer, allowing for rapid field analysis of
environmental samples.
The M200 is a portable, high-speed gas
chromatograph that samples gases and vapors,
separates any volatile components, and then
identifies and calculates the concentrations of these
compounds. Only vapor-phase samples can be
introduced into the M200. Purgeable organics from
soil and water matrices are collected via a portable
sample concentrator and converted to vapor phase
for analysis by the M200. No liquids should ever be
introduced into the M200 GC system.
7.2 METHOD SUMMARY
A Macintosh computer system connected to the
M200 processes sample data and identifies selected
compounds found in vapor-phase samples. The
M200 unit contains two high-resolution capillary
columns. Simple front panel controls on the unit
allow the operator to adjust all method parameters
(Figure 2, Appendix D). After the correct
parameters are set, a vapor sample is drawn into
the unit via the sample port and an internal vacuum
pump. The sample gas is then analyzed on one or
both capillary columns and specific volatile
compounds are detected, separated and identified
by the attached computer system.
Calibration standards must be analyzed prior to
field sampling. Once the calibration has been
validated and the points plotted using the Macintosh
library and software, sample analyses can proceed.
The Macintosh calibration library currently contains
only target compounds historically encountered in
U.S. EPA/ERT field work.
7.3 SAMPLE PRESERVATION,
CONTAINERS, HANDLING, AND
STORAGE
Since the M200 is involved with vapor-phase
samples, all samples are collected directly or stored
in Tedlar gas sampling bags, as per ERT SOP
#2050, Tedlar Bag Sampling.
The actual introduction of any calibration or sample
gas into the instrument is done by attaching a 2 cm3
Beckton-Dickerson glass syringe via a Teflon Luer
lock valve directly to the sampling inlet port in the
front of the unit.
7.4 INTERFERENCES AND
POTENTIAL PROBLEMS
Even considering the powerful analytical capabilities
in the M200's design configuration, the instrument
has several inherent limitations that impact its
ability to be used during responses to chemical
releases. These limitations are as follows:
Commercial versions of the device can detect
only preselected compounds that can be
identified by parameters stored within its
internal read-only memory (ROM) library.
Large quantities of other vapors could be
present and may seriously interfere with the
analysis using the M200.
The presence of common fuels containing many
individual components, such as gasoline, will
confuse the M200's computerized interpretation
of data.
Large quantities of a preselected vapor may
overload the capillary columns, and the
retention times of the preselected compounds
may fall outside of expected retention time
windows.
Commercial versions of the device are
programmed with detection limits which are
too high (by factors of 10 to 100) for
determining levels of hazardous chemicals at or
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below TLV concentrations. For typical soil gas
analysis, parts per billion (ppb) will be required,
and the M200 cannot detect levels that low. To
compensate, a sample preconcentrator is used
to concentrate the compounds of interest prior
to injection.
7.5 EQUIPMENT/APPARATUS
In addition to the basic Micromonitor M200 unit,
several optional pieces of equipment are required
for its operation. These pieces include a 12-volt
power supply, a Macintosh computer system, and a
RS232DB9-DB9 cable (Figure 3, Appendix D). An
optional sample preconcentrator is required to
analyze air samples with detection limits in the parts
per billion range. If pur gable organics are to be
determined in soil or water matrices, the sample
preconcentrator is a required piece of equipment.
7.6 REAGENTS
The M200 utilizes high purity (99.995% or above)
helium as a carrier gas. Pressure at the two-stage
regulator on the tank should be approximately 80
psig. The capillary column head pressure inside the
M200 unit should be 15 to 40 psig. This capillary
column head pressure can be adjusted via two
regulators found on the back of the instrument
(Figure 4, Appendix D).
Gas standards are purchased as certified mixtures at
fairly high concentrations (i.e., 10 ppm or greater)
from Scott Gas or Matheson. These concentrations
are for subsequent dilution to various concentrations
that enable construction of a standard calibration
curve.
liquid phase standards, if required, must be of the
highest purity, such as Aldrich Gold Label or
Supelco Environmental standards kits. If air is to
be used for sample/standards dilutions, it must also
be ultrahigh purity gas.
7.7 PROCEDURES
1. Plug in your M200 unit. The following message
should appear on the display reading: "Self test
OK."
2. An asterisk (*) should appear in the first
character of the display within 3 minutes of
turning on the unit, signaling that the unit is
ready (Le., the temperatures are at the
setpoints, the pressures are above 5 psig and
the system self test found no errors). If the
asterisk does not appear, consult the
troubleshooting guide in Appendix C.
3. Enter the method parameters by pressing the
< METHOD > key. The first item reads
"Column Temperature." If column temperature
is 30ฐC, press < ENTER > to accept the value
and go on to the next item. If it does not read
30ฐC, press or to achieve
this required temperature. Once 30ฐC is
shown, press < ENTER > to accept the value
and to advance to the next parameter. The
temperature can be set at any level between 30s
and 180ฐC. Table 4 gives appropriate values
for three often-used GC columns.
4. Continue through all the items in the method
the same way.
5. Now read the "Column Head Pressure" on the
front panel by pressing < STATUS >. Press
< ENTER > once to advance to the next line
where the column pressure will be indicated.
6. Adjust the pressure regulator in the rear of the
instrument until the pressure reads about 20ฑ5
psig (or the appropriate pressure required for
the selected method). Press < STATUS > to
monitor column pressure.
7.7.1 Macintosh Software
The procedures used when the M200 unit is being
controlled from the computer system are outlined in
the Macintosh M200 Chromatography Applications
Manual.
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Table 4: M-200 Operating Conditions for Various Sample Columns
Column Type
Operating Conditions
DB-5/DB-1701
MOL Sieve 5A
HAYESEPA
Column Head Pressure
20 ฑ 5 psig
12 + 5 psig
18 ฑ 5 psig
Column Temperature
30ฐ C
60ฐ C
60ฐ C
Run Time
40 sec
30 sec
40 sec
Sampling Time
5 sec
5 sec
5 sec
Inject Time
40 msec
40 msec
40 msec
Detector filament
on
on
on
Auto Zero
on
on
on
Detector Sensitivity
medium
medium
medium
Integrator/ Data System Conditions
Printer/Plotter
chart speed
20 cm/min
Printer/Plotter
Attenuation
256X
Input Signal
1 Volt
7.7.2 Calibration
The M2001 software used with the M200 GC uses
Retention Time Indices (RTIs) based on a
homologous series of compounds, in this case n-
alkanes. A calibration run using three or more n-
alkanes is run at the appropriate GC conditions.
The RTIs are updated in the library as per M2Q01
manual. The RTIs for the entire library are not
updated by correcting stored library values against
the current "experimental" calibration run. It is
important to bracket the entire library retention
time with the three or more n-alkanes used in .the
calibration run.
A second calibration run using the target
compounds of interest is then performed. This
second calibration establishes the correct response
factor which will be used to calculate the
concentrations of the target compounds. This
second calibration is required because the first
calibration, using the n-alkanes, will establish the
correct RTIs but will not yield the correct response
factors for the target compounds. Therefore, two
calibrations, the first to establish the correct RTI,
and the second to calculate the correct response
factor, are required at least once a day. Note: the
results for compounds not in the calibration run are
estimated from the response factor of their nearest
neighbor.
The generation of calibration standards can be
performed either at the site or in the laboratory
prior to entering the field. In the latter case,
standards must still be run in the field to ensure
that the calibration runs stored on the data disks
are valid and close to standards run in the lab.
Dilutions are typically made from the certified gas
standards cylinders using Hamilton 500, 1000 and
1500 cm3 model "Super syringes" and Tedlar
sampling bags. Simple volumetric dilutions are
made and the set of standards analyzed as if they
were typical samples. If the sample pre-
concentrator is used, the trapping efficiency must be
recorded.
At least three concentrations of each standard must
be run. Preferably more standards are analyzed to
establish the minimum ranges for the linear
41
-------
response of the detectors for each individual target
compound. Linear regression must be performed
and an R2 value of 0.90 or greater should be
achieved.
7.7.3 Sample Analysis
To analyze a sample, fill a 2.0 cm3 glass syringe with
the sample, attach a Teflon Luer lock to the syringe
tip and carefully place this assembly into the sample
port located on the unit. Make sure the Luer lock
is in the open position. The interna] sampling
pump will automatically draw a portion of the
sample from the syringe into the instrument, once
the injection command is executed (Figure 3,
Appendix D).
7.8 CALCULATIONS
A calibration curve of at least three concentrations
must be constructed for each target compound. A
straight line equation in the form of y = (m)(x) +
b; (where: x = concentration, y = area counts, m
= slope and b = the intercept) is fit to the
standard's raw data. The (y), or the unknown
concentration for the sample, is determined from
the above straight line equation. Non-linear data is
indicative of erroneous detector response.
Alternatively, sample concentration can be
calculated as below:
Sample Cone. = (standard conc.1 (sample areat
(standard area)
The M2001 software will automatically calculate the
concentration based on the response factor
generated in the calibration mode of the program.
Calibrations can be single point or multipoint
calculations.
7.9 QUALITY ASSURANCE/
QUALITY CONTROL
The following QA/QC protocols are applicable:
A complete calibration curve must be run
daily.
Duplicates of a standard, in the mid-range
of the calibration curve and preferably
close to sample results, should be run every
10 samples to ensure constant detector
response.
Two or three duplicates for each sample
should also be run. These duplicate
responses should be within 10-20% of each
other in terms of area count and retention
time values.
Matrix spikes, or spiking samples with
known levels of standards, must be run
along with the samples, and should bracket
the levels found in the field samples.
The same Tedlar bag may be analyzed by
other field instrumentation (e.g., Photovac,
OVA, Sentex, etc.) and/or collected into
tubes for GC/MS confirmation. If Tedlar
bags are used to prepare standards, the
time of preparation should be noted.
During sample analysis, one of the
standards should be periodically re-
analyzed to ascertain if any sample loss
occurs in the bag over time.
A performance evaluation sample (PE) is
typically sent along to determine if any loss
or contamination occurs from transit or
handling during sampling.
A trip blank of zero air is also sent and
analyzed at the end of the sampling run to
determine if any contamination of the
Tedlar bags occurred during transit.
7.10 DATA VALIDATION
The Retention Time Index (RTI) is used for peak
identifications. If peaks are eluting close to the
target compounds, sample spikes using known levels
of target compounds can be prepared to identify the
absence/presence of these target compounds in the
samples. Typically, only the RTI is needed to
identify the peaks of interest. Quantification is
determined from the linear calibration curve, and by
solving for concentration (y) from the straight line
equation. The coefficient of variation on the
straight line equation should have an R2 of 0.90 or
greater. Confirmation of the identity of any
particular target compound must be done by other
analytical methods, typically GC/MS.
42
-------
Alternatively, a statistical approach to data
validation can be sought. Once the linear range is
established, analyze an appropriate standard, either
a low or midrange concentration, 10 or more times
throughout the day. Determine the standard
deviation of the mean (o(N-l)) for the response of
the standard selected. The statistical method
detection limit, or MDL, is 3 times the standard
deviation (3o). The method quantitation limit, or
MQL, is then 10 times the standard deviation (lOo).
Results below the MDL are considered "nondetects"
(ND). Results above the MDL but below the MQL
are considered "detected," but below the
quantitation limit and thus are ascribed a "J" value.
This "J" value flags the data as questionable.
Results above the MQL are considered statistically
reliable data.
7.11 HEALTH AND SAFETY
When working with potentially hazardous materials,
follow U.S. EPA, OSHA, and corporate health and
safety practices. Analysis should be performed in a
well-ventilated room. The sample vent port on the
back of the M200 should be equipped with either a
carbon scrubber or a long Tygon tube to vent
sample gases outside of the work area. All carrier
gas cylinders must be securely bolted to a table or
piece of heavy furniture. When liquid reagents are
used to prepare standards, the work should be
performed under a vented hood with the analyst
wearing safety glasses and disposable protective
gloves.
-------
44
-------
APPENDIX A
Ionization Potentials
45
-------
46
-------
Ionization Potentials
Some Atoms and Simple Molecules
Atom/Molecule
IP
(eV)
Molecule
IP
(eV)
H
13.595
h
9.28
C
11.264
HF
15.77
N
14.54
HC1
12.74
O
13.614
HBr
11.62
Si
8.149
HI
10.38
S
10357
so2
1234
F
17.42
COj
13.79
CI
13.01
COS
11.18
Br
11.84
cs2
10.08
I
10.48
NjO
12.90
h2
15.426
no2
9.78
n2
15.580
o,
12.80
o2
12.075
h2o
12.59
CO
14.01
HjS
10.46
CN
15.13
HjSe
9.88
NO
9.25
H2Te
9.14
CH
11.1
HCN
13.91
OH
13.18
QN2
13.8
f2
15.7
nh3
10.15
Cl2
11.48
ch3
9.840
Br2
10.55
ch4
12.98
47
-------
Ionization Potentials (continued)
Alkyt Halides
Molecule
IP
(eV)
Molecule
IP
(eV)
HC1
12.74
CH2BrCl
10.77
Cl2
11.48
CHBr2Cl
1039
chซ
12.98
ethyl bromide
10.29
methyl chloride
11.28
1,1-dibromoe thane
10.19
dichloromethane
1135
l-bromo-2-chloroethane
10.63
trichloromethane
11.42
1-bromopropane
10.18
tetrachloromethane
11.47
2-bromopropane
10.075
ethyl chloride
10.98
1,3-dibromopropane
10.07
1,2-dichloroethane
11.12
1-bromobutane
10.13
1-chloropropane
10.82
2-bromobutane
9.98
2-chloropropane
10.78
l-bromo-2-methylpropane
10.09
1,2-dichloropropane
10.87
2-bromo-2-methylpropane
9.89
1,3-dichloropropane
10.85
1-bromopentane
10.10
1-chlorobutane
10.67
HI
1038
2-chlorobutane
10.65
h
9.28
l-chloro-2-methyIpropane
10.66
methyl iodide
9.54
2-chloro-2-methylpropane
10.61
diiodomethane
9.34
HBr
11.62
ethyl iodide
9.33
Br2
10.55
1-iodopropane
9.26
methyl bromide
10.53
2-iodopropane
9.17
dibromomethane
10.49
1-iodobutane
9.21
tribromomethane
10.51
2-iodobutane
9.09
48
-------
Ionization Potentials (continued)
Alkji Halides (continued)
Paraffins and CycloparafTins
Molecule
IP
(eV)
Molecule
IP
(eV)
l-iodo-2-methylpropane
9.18
methane
12.98
2-iodo-2-methy]propane
9.02
ethane
11.65
1-iodopentane
9.19
propane
11.07
f2
15.70
n-butane
10.63
HF
15.77
i-butane
10.57
CFCI3 (Freon 11)
11.77
n-pentane
1035
CF2C12 (Freon 12)
1231
i-pentane
1032
CF3C1 (Freon 13)
12.91
2,2-dimethylpropane
1035
CHClFj (Freon 22)
12.45
n-hexane
10.18
CFBr3
10.67
2-methylpentane
10.12
CF2Br2
11.07
3-methylpentane
10.08
CHjCFjCl (Genetron 101)
11.98
2,2-dimethylbutane
10.06
CFCijCFjCl
11.99
23-dimethyIbutane
10.02
CF3CCI3 (Freon 113)
11.78
n-heptane
10.08
CFHBrCHjBr
10.75
2,2,4-trimethylpentane
9.86
CFjBrCHjBr
10.83
cyclopropane
10.06
CFjCHjI
10.00
cyclopentane
10.53
n-CjF7I
10.36
cyclohexane
9.88
n-CjFTCHjCl
11.84
methyl cyclohexane
9.85
ii-QFtCH,!
9.96
49
-------
Ionization Potentials (continued)
Aliphatic Alcohol, Ether, Thiol, and Sulfides
Aliphatic Aldehydes and Ketones
Molecule
IP
(eV)
Molecule
IP
(eV)
h2o
12.59
co2
13.79
methyl alcohol
10.85
formaldehyde
10.87
ethyl alcohol
10.48
acetaldehyde
10.21
n-propyl alcohol
10.20
propionaldehyde
9.98
i-propyl alcohol
10.16
n-butyr aldehyde
9.86
n-butyl alcohol
10.04
isobutyraldehyde
9.74
dimethyl ether
10.00
n-valeraldehyde
9.82
diethyl ether
9.53
isovaleraldehyde
9.71
n-propyl ether
9.27
acrolein
10.10
i-propyl ether
9.20
crotonaldehyde
9.73
HjS
10.46
benzaldehyde
9.53
methanethiol
9.440
acetone
9.69
ethanethiol
9.285
methyl ethyl ketone
9.53
1-propanethiol
9.195
methyl n-propyl ketone
939
1-butanethiol
9.14
methyl i-propyl ketone
932
dimethyl sulfide
8.685
diethyl ketone
9.32
ethyl methyl sulfide
8.55
methyl n-butyl ketone
934
diethyl sulfide
8.430
methyl i-butyl ketone
930
di-n-propyl sulfide
8.30
3,3-dimethyl butanone
9.17
2-heptanone
9.33
cyclopentanone
9.26
cyclohexanone
9.14
23 butanedione
9.23
2,4-pentanedione
8.87
50
-------
Ionization Potentials (continued)
Aliphatic Acids and Esters
Aliphatic Amines and Amides
Molecule
IP
(eV)
Molecule
IP
(eV)
co2
13.79
NH3
10.15
formic acid
11.05
methyl amine
8.97
acetic acid
1037
ethyl amine
8.86
propionic acid
10.24
n-propyl amine
8.78
n-butyric acid
10.16
i-propyl amine
8.72
isobutyric acid
10.02
n-butyl amine
8.71
n-valeric acid
10.12
i-butyl amine
8.70
methyl formate
10.815
s-butyl amine
8.70
ethyl formate
10.61
t-butyl amine
8.64
n-propyl formate
1054
dimethyl amine
8.24
n-butyl formate
1050
diethyl amine
8.01
isobutyl formate
10.46
di-n-propyl amine
7.84
methyl acetate
10.27
di-i-propyl amine
7.73
ethyl acetate
10.11
di-n-butyl amine
7.69
n-propyl acetate
10.04
trimethyl amine
7.82
isopropyl acetate
9.99
triethyl amine
750
n-butyl acetate
10.01
tri-n-propyl amine
7.23
isobutyl acetate
9.97
formamide
10.25
sec-butyl acetate
9.91
acetamide
9.77
methyl propionate
10.15
N-methyl acetamide
8.90
ethyl propionate
10.00
N,N-dimethyl formamide
9.12
methyl n-butyrate
10.07
N,N-dimethyl acetamide
8.81
methyl isobutyrate
9.98
N,N-diethyl formamide
8.89
N,N-diethyl acetamide
8.60
51
-------
Ionization Potentials (continued)
Other Aliphatic Molecules with N Atom
Olefins, Cyclo-oleflns, Polenes, Acetylenes
Molecule
IP
(eV)
Molecule
IP
(eV)
nitromethane
11.08
ethylene
10.515
nitroethane
10.88
propylene
9.73
1-nitropropane
10.81
1-butene
9.58
2-nitropropane
10.71
2-methylpropene
9.23
HCN
13.91
trans-2-butene
9.13
acetonitrile
12.22
cis-2-butene
9.13
propionitrile
11.84
1-pentene
930
n-butyronitrile
11.67
2-methyl-l-butene
9.12
acrylonitrile
10.91
3-methyl- 1-butene
931
3-butene-nitrile
1039
3-methyl-2-butene
8.67
ethyl nitrate
11.22
1-hexene
9.46
n-propyl nitrate
1,3-butadiene
9.07
methyl thiocyanate
10.065
isoprene
8.845
ethyl thiocyanate
9.89
cyclopentene
9.01
methyl isothiocyanate
9.25
cyclohexene
8.945
ethyl isothiocyanate
9.14
4-methylcyclohexene
8.91
4-cinylcyclohexene
8.93
cyclo-octatetraene
7.99
acetylene
11.41
propyne
1036
1-butyne
10.18
52
-------
Ionization Potentials (continued)
Some Derivatives of Olefins
Heterocyclic Molecules
Molecule
IP
(eV)
Molecule
IP
(eV)
vinyl chloride
9.995
fur an
8.89
cis-dichloroethylene
9.65
2-methyl fur an
839
trans-dichloroethylene
9.66
2-furaldehyde
921
trichloroethylene
9.45
tetrahydrofuian
9J54
tetrachloroethylene
932
dihydropyran
834
vinyl bromide
9.80
tetrahydropyran
926
1,2-dibromoethylene
9.45
thiophene
8.860
tribromoethylene
9.27
2-chlorothiophene
8.68
3-chloropropene
10.04
2-bromothiophene
8.63
23-dichloropropene
9.82
pyrrole
8.20
1-bromopropene
930
pyridine
932
3-bromopropene
9.7
2-picoline
9.02
CFjCCl = CClCFj
1036
3-picoline
9.04
n-CjFuCF=CF2
10.48
4-picoline
9.04
acrolein
10.10
23-lutidine
8.85
crotonaldehyde
9.73
2,4-lutidine
8.85
mesityl oxide
9.08
2,6-lutidine
8.85
vinyl methyl ether
8.93
allyi alcohol
9.67
vinyl acetate
9.19
53
-------
Ionization Potentials (continued)
Aromatic Compounds
Molecule
IP
(eV)
Molecule
IP
(eV)
benzene
9.245
2-methylnapthalene
7.955
toluene
8.82
biphenyl
827
ethyl benzene
8.76
phenol
830
n-propyl benzene
8.72
anisole
8.22
i-propyl benzene
8.69
phenetole
8.13
n-butyl benzene
8.69
benzaldehyde
9.53
s-butyl benzene
8.68
acetophenone
9.27
t-butyl benzene
8.68
benzenethiol
833
o-xylene
8.56
phenyl isocyanate
8.77
m-xylene
8J6
phenyl isothiocyanate
8.520
p-xylene
8.445
benzonitrile
9.705
mesitylene
8.40
nitrobenzene
9.92
durene
8.025
aniline
7.70
styrene
8.47
fluoro-benzene
9.195
a-methyl styrene
835
chloro-benzene
9.07
ethynylbenzene
8.815
bromo-benzene
8.98
napthalene
8.12
iodo-benzene
8.73
1-methylnapthalene
7.96
o-dichlorobenzene
9.07
54
-------
Ionization Potentials (continued)
Aromatic Compounds (continued)
Miscellaneous Molecules
Molecule
IP
(eV)
Molecule
IP
(eV)
m-dichlorobenzene
9.12
ethylene oxide
10565
p-dichlorobenzene
8.94
propylene oxide
1022
l-chloro-2-fluorobenzene
9.155
p-dioxane
9.13
l-chloro-3-fluorobenzene
9.21
dimethoxymethane
10.00
l-bromo-4-fluorobenzene
8.99
diethoxymethane
9.70
o-fluorotoluene
8.915
1,1-dimethoxyethane
9.65
m-fluorotoluene
8.915
propiolactone
9.70
p-fluorotoluene
8.785
methyl disulfide
8.46
o-chlorotoluene
8.83
ethyl disulfide
8.27
m-chlorotoluene
8.83
diethyl sulfite
9.68
p-chlorotoluene
8.70
thiolacetic acid
10.00
o-bromotoluene
8.79
acetyl chloride
11.02
m-bromotoluene
8.81
acetyl bromide
10.55
p-bromotoluene
8.67
cyclo-CftHjjCFj
10.46
o-iodotoluene
8.62
(n-CjF7)(CH3)C=0
1038
m-iodotoluene
8.61
trichlorovinylsilane
10.79
p-iodotoluene
8.50
(c2f3)3n
11.7
benzotrifluoride
9.68
isoprene
9.08
o-fluorophenol
8.66
phosgene
11.77
55
-------
56
-------
APPENDIX B
Photovac Maintenance and Calibration
57
-------
58
-------
Photovac Maintenance and Calibration:
Supplement to SOPs #2107 and #2108
PHOTOVAC 10A10
Septum Change
The Photovac 10A10 uses a Teflon-faced, silicon
rubber, 6-mm diameter septum. The Hamilton
"Micro Sep" F-138 is suitable. The septum can
easily be replaced with the following procedure.
1. Unscrew septum retainer.
2. Remove the old septum using the needle of one
of the gas tight syringes available for sample
injection.
3. Insert the new septum, Teflon face down.
4. Carefully screw the retainer back into place
firmly, but without overtightening.
A 10 to 20 minute stabilization period may be
required due to a temporary interruption of the
carrier gas flow when the septum is changed.
Column Maintenance
The standard Photovac 10A10 is equipped with a 4
foot by 1/8-inch OD Teflon tube packed with 3%
SE-30 on 80/100 mesh Chromosorb G for field
surveys and analyses requiring detailed separations.
Normally the column will be connected for manual
operation.
New columns must be conditioned overnight with
ultrahigh purity helium (or nitrogen) at a
temperature of 100ฐC and a flow rate of 10
cm3/min. Reconditioning of older columns is
accomplished under the same conditions.
To access the column, utilize the following
procedures:
1. Never remove the panel while the instrument is
connected to the main power supply.
Table F: Photovac Maintenance and Calibration Schedule
Function
Procedure/F requency
Battery Charge (when instrument has been
operating exclusively on wall current)
Charge for 10 hours on "low" setting; every 3
months.
Battery Charge (when instrument has been
operating exclusively on batteries)
Charge for 1 1/2 hours on "high" setting for every
hour of use (don't overcharge); after each use.
Calibration
Calibrate after every 24-hour period of use (see
section 4.72).
Septum Change
Change after approximately every 40 sample
injections (see section 4.75).
Column Reconditioning
Recondition every 3 months, after heavy use, or
whenever installing a new column (see section
4.7.6).
59
-------
2. Disconnect the AC cord.
3. Disconnect the chart recorder lead.
4. Disconnect the lecture bottle carrier gas supply.
5. Remove the four Phillips screws securing the
panel to the case and remove the screw
attaching the lid.
6. Grasp the panel assembly by the cylinder
clamp. Gently lift the rear of the panel clear of
the case rim and ease the panel assembly
backward from the front rim. Lift the panel
assembly clear.
7. Gently remove the wire harness connection
from the circuit board into which it is plugged.
Remove the nine Phillips screws from the gold
box and lift clear the lid/circuit board
subassembly. The interior of the column/ion
cell chamber is now accessible.
8. To remove the column, locate the 2
compression fittings at either end of the column
(ion cell body and injection port). Using a
5/16-inch, open-ended wrench, loosen these
fittings. Unscrew the fitting with your hand and
remove column.
9 To replace the column, reverse the previous
steps and take special care not to damage the
threads on the compression fittings. Fittings
are made finger tight and then the 5/16-inch
open-ended wrench is used to give an additional
1/8-inch turn to assure fitting seating.
PHOTOVAC 10S SERIES
UV Source
The ultraviolet light source is available to check
proper performance. Occasional starting problems
can be encountered. After switching the Photovac
on, the LCD will respond with "Lamp not ready
please wait." This is superseded by "Ready enter
command" as soon as the lamp ignites.
Septum
The septum is 6-mm in diameter and composed of
silicone rubber with a Teflon face. The Teflon face
is always mounted downwards in the injection port.
1. To change the septum, take a spare syringe
needle and push it down the septum retainer
channel, so that it penetrates the septum.
2. Leaving the needle in place, unscrew the
retainer and withdraw it, with the septum still
impaled on the needle. Handle the new
septum as little as possible between your
fingers.
3. Using the left hand, position the new septum,
(Teflon face down) at the end of the retainer
and push the needle through with the right
hand to hold the septum in the correct
alignment.
4. Carefully screw the retainer back into position.
The needle will maintain the septum in the
correct position until it is seated.
The septum retainer must not be over tightened, as
this will cause unusual resistance to penetration by
the needle and may cause needle blockage.
Column Maintenance
The 10S Series Photovac is usually supplied with a
6-inch 5% SE-30 pre-column and a 4-foot 5% SE-
30 analytical column suitable for field screening a
variety of chlorinated and nonchlorinated alkene
and aromatic compounds with adequate resolution.
The SE-30 (dimethylsilicone gum) is a packed
column. An alternative column, the CP Sil-5
(Dimethylpolysiloxane) capillary column, is also
suitable for general field screening analysis.
New packed columns and heavily contaminated
columns must be conditioned/reconditioned prior to
use, using the column conditioning adaptor and
UHP helium or nitrogen, at a flow rate of 5-10
cm3/min, at 100ฐC overnight.
The capillary column is conditioned overnight with
the same carrier gas. However, the maximum
recommended temperature is 50ฐC if using the
plastic encased capillary column supplied by
Photovac International.
To access the column, utilize the following
procedure:
1. Release the catch of the computer module
located at the upper left hand corner of the
module.
60
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2. Raise the hinged module and securein; the^c
open position.
3. Carefully unscrew compression fittings and
remove the pre-column and analytical column.
4. To replace the columns, tighten the Teflon
compression fittings, finger tight, being careful
not to strip the threads, as this may result in
leakage.
When the Photovac is not in use, it is advisable to
maintain a carrier gas flow (2-5 cm3/min) through
the column and Photovac valve system. This will
reduce possible contamination from outside sources,
and off gassing of possible contaminants which may
have accumulated in the detector or injection port.
This will also aid in readiness for emergency
response operations.
Batteries
The 10S Photovac portable GC uses a single 12V, 6-
A rechargeable lead/acid battery. It is usually
sufficient for at least 8 hours of continuous
operation, depending on the duty cycle chosen for
the valves in the case of continuous monitoring.
The battery is guaranteed for 300 charge/discharge
cycles which is equivalent to a year of very heavy
activity.
A battery declining in charge will make itself known
to the user by automatically shutting off the
instrument. It will require an overnight charge.
In order to re-charge, connect the unit to the AC
main. As long as the instrument is connected to the
main, the batteries will be trickle charged or in a
standby mode. Battery charging and monitoring are
matters which are under the control of the
computer; to check status, depress the "up arrow"
key. Full charge will show 13.6 volts. When
charging overnight, leave unit on with carrier flow
at 5-7 mL/mm. This is equivalent to a high charge.
Printer/Plotter Service
As a general rule, this device requires little service
beyond the timely replacement of pens and paper.
To replace a pen, turn the Photovac on and depress
the key. The pen turret will move to the
right and stop. If the correct color Pen is
uppermost, engage your fingernail in the ridges on
the little nylon tab, located in the bottom right hand
corner of the printer aperture and pull the tab
towards you to eject the rear-end of the pen.
If the turret presents the wrong color pen for
replacement, briefly depress the < PEN > key and
the turret will rotate 90 degrees and present the
next color, and so on. Lift the pen out and insert a
new one, making sure that the ball tip passes
through the tiny aperture in the metal plate located
close to the writing surface. Press the rear-end of
the new pen into its position in the turret and
briefly depress the key to bring the
printer back "on line."
Both paper and pens are readily available from any
"Radio Shack" or similar store. In the event of any
difficulty in locating a supply, contact Photovac.
Troubleshooting information and corrective action
procedures can be found in Appendix C.
61
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62
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APPENDIX C
Troubleshooting Guides
63
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64
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Troubleshooting Guide for Photovac 10A10 SOP #2107
Problem
Probable Cause
Remedy
1
No chromatographic
response.
No carrier gas flow.
Check at Out port with flow
gauge.
Batteries flat (if on battery
operation).
Plug Into AC and check
again.
Electrometer saturated.
Turn "attenuation" to set
meter to 0, if "offset" reads 10
or more, the instrument is
saturated.
2
Unacceptable baseline
drift
Unit has been subjected to targe
temperature change.
Allow to stabilize until clear.
A very concentrated sample has
recently been introduced, resulting
in excessive tailing".
Allow to self purge until clear.
Unacceptable contamination levels
In carrier gas supply.
Change carrier gas supply
and allow instrument to
stabilize.
The unit is charging and the
resulting heat is affecting the
column.
Turn Charge switch to Off.
3
Deterioration of
sensitivity.
Syringe has leaky plunger.
Try new syringe.
Column needs conditioning.
Condition column.
Septum leaking.
Change septum.
Column fittings leak.
Disassemble and check for
leaks around fittings with
soap solution, while under
pressure.
Deterioration due to ozone
contamination after 1-3 years of
operation.
Decrease attenuation; replace
detector.
4
Unacceptable low
frequency noise.
Column needs conditioning.
Condition column.
5
Peaks el lite very
slowly.
Carrier flow rate Is too slow.
Increase flow rate.
6
Peaks elutlng too fast
Carrier flow rate is too high.
Decrease flow rate.
7
Peak has flat top.
Electrometer has saturated.
m
Lower Injection volume. Pre-
dilute sample and repeat.
65
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Problem
Probable Cause
Remedy
8
Peak is misshapen
wtlh considerable
tailing.
Improper injection.
Repeat.
Row Is too sJow.
Increase flow.
Improper Injection technique.
Repeat.
Peak is developing from an earlier
Injection.
Allow greater time between
injections or Install shorter
column.
Compound is wrongly matched to
Column.
Select appropriate column.
Power supply Inadequate.
9
Source off light stays
on after 5 minutes.
Batteries low (If battery operated).
Plug In AC connector.
Adjust potentiometer under
aluminum cylindrical case by
45s clockwise increments.
Wire attachments to power supply
not secure.
Secure wire attachments.
Tube driver mismatched.
Contact Photovac for advice
(516)351-5800.
Power supply Inadequate.
10
Electrometer does not
return to zero.
Electrometer saturated.
Allow carrier flow for
extended period without
sample Injection.
66
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Troubleshooting Guide for Photovac 10S: Supplement to SOP #2108
Lamp won't light
Note: if the lamp wont light, turn the instrument
off. If the instrument is left on for more than 3
minutes, the oscillator board will be blown.
1. First try tuning the lamp using the Photovac
plastic screwdriver, at the detector chamber
box. Lamp source tuning and replacement
procedures follow.
a. The Photovac UV source is located inside
the black box marked PHOTOVAC, which
is situated beneath the hinged electronic
module. There is access for a special
tuning tool, through an identified hole at
the rear of the lid. The tool is provided
and is located in a special clip on the front
face of the black box. Do not use a metal
tool for this adjustment as this may cause
an electrical short circuit.
b. Observe the "Lamp not ready, please wait"
message seen on the LCD. Engage the
tool in the slot of the small screw beneath
the hole in the box lid. Rotate the screw
slowly in a clockwise direction. You may
have to make several slow rotations until
the message changes to "Ready enter
command." Note the screw repeats its
setting every 360ฐ of rotation. Once the
"Ready" message appears, turn the
instrument off (by pressing )
and then turn it on again. After a
maximum of 3 minutes the "Ready"
message should return. If it does not,
repeat the procedure. If unable to achieve
the "Read/ state at all, it is probable that
the lamp has failed. Proceed as follows:
c. Turn the instrument off. Remove the four
securing screws from the lid of the detector
box. Inside you will see a white Teflon
cylinder screwed into the right wall of the
box. This cylinder is the lamp holder and
has a silver wire wound around it in a
spiral. There is a connecting wire attached
to the free end of the lamp holder. Pull
this gently out of its socket. Gently
unscrew the lamp holder and withdraw it:
you will see the lamp inside as you pull it
away from the wall. Be careful not to drop
the lamp. Take the new lamp, being very
careful not to touch the window end with
your fingers. Remove the old lamp and
replace it with the new one. The O-ring on
the lamp should be positioned about 5 mm
from the end face of the window. Screw
the holder back into place. Make sore It
goes in straight and is not cross-threaded.
Tighten until resistance from the O-ring is
felt. Replace the connecting wire into its
socket. Replace the lid and make sure all
four screws are returned and are tight.
d. The instrument is now ready to start; press
and tune if necessary.
e. Tuning also affects the amount of power
consumed by the instrument (lamp)- Press
and to obtain the
status report. Check to ensure the value of
"POWER" is in the 20 to 50 range (200 to
500 mA). If the power exceeds 50, the
battery life will be shortened significantly.
Try to aim for a reading of 35 to 40,
consistent with a reliable starting.
f. While you are tuning the lamp, you can
also check the power consumption without
printing the status report.
g. Press and type in "7853" and
< ENTER >. The message "Lamp power"
followed by a number, possibly "30," will
show. Then you can tune the lamp
accordingly.
2. If, after a few tries at tuning the lamp, it still
won't light, turn off the instrument. Remove
the detector chamber lid, remove the yellow
wire from the S port on the oscillator board.
Now turn on the instrument, and using the
plastic screwdriver tune the lamp to its
brightest violet color. Replace the yellow wire
into the S port, and replace the detector
chamber lid.
3. As a last resort, change the lamp. See
procedure l.c above.
67
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No Flow - Valves are Open
1. Check the carrier gas cylinder and regulator to
ensure all valves are open.
2. Check flowmeter and injection port. If the
injection port is over-tightened, the flow will be
cut off.
3. Check column fittings (should only be finger
tight) and check the plumbing configuration. If
the GC is set up for serial flow, then either the
green or black carrier gas tubing, the tee port
on the capillary column, and the clear tubing
coming from the top right side of the column
chamber will be closed off. With the backflush
setup the black carrier gas tubing will be going
into the first port in valve 3. The green or blue
valves 4 & 5, and the tee port on the capillary
column will be hooked up to the last port in
valve 3 via clear tubing.
Low Sensitivity
1. Leak in system.
2. Plugged syringe.
3. Gain too low.
No Peaks Appear
1. Plugged syringe.
2. Leak in system/no flow.
3. Check events (Test key) and all parameters;
press , then
press and < ENTER >.
Keyboard Jam
1. A key is jammed when it won't respond to any
commands. If one key is jammed the whole
keyboard is jammed. To fix, lift off key with
needle-nose pliers and lift up the metal tab with
the needle-nose pliers. Replace the key and
press down on the key, a clicking noise should
be heard. Usually the last key pressed is the
key that is jammed, also check the most
frequently used keys.
2. As a last resort, hit the red reset button
underneath the green piece of cardboard near
the detector chamber. Re-enter all parameters.
Instrument Shuts Itself Off After
Printing the Message, "Batteries low,
AC power required"
1. This can be avoided two ways; first use a power
surge cord, and second allow the GCs to run
off their internal batteries for four (4) hours
then charge overnight prior to ralcing the
instruments out in the field. This will keep the
batteries from going into deep discharge.
2. If the instrument does this out in the field, then
run the GC using the Photovac external battery.
(Note: it must be recharged every six hours.)
Pens won't Print
1. Check to make sure the paper is fed properly.
2. Check the metal tables in front of the printer
barrel; they may be bent. With needle-nose
pliers or tweezers, push the metal tabs towards
the keyboard (away from the pen tips).
3. Make sure the metal pen holder on the pen
barrel is not bent. Use a paint brush to brush
away any dust from the printer.
Negative Baseline
1. Regular pressure is too low. Pressure should
be 20-30 psi.
2. Check for a leak in the system.
3. Compounds from last run are going past the
detector which causes the baseline to go
negative, or the column needs more purging.
An immediate fix is to put in two septa.
"Valve Remains On" Indicated on LCD.
"On" time greater than "off time. Check "list" or
"event" status on LCD.
68
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Sensitivity Too Low
Printer/valve cycle Is too frequent
1. Calibration is wrong. Check.
2. Syringe is leaking. Check.
3. Probable leak in system. Finger tighten all
suspect fittings. Check column attachments and
injection port. Do not over tighten fittings.
4. Gain setting is too low. Increase.
5. Valve timing is wrong. Check EVENTS, it is
possible that the backflush is too fast see
above. It is also possible that injection time is
too short.
6. Lamp is failing. Replace with spare and try
again.
Peak appears but Is not recognized
1. Peak not calibrated. Do qualitative calibration;
see Exercise (8) in User's Manual.
2. Increase subsequent calibration frequency.
3 Check peak in library for proper ID, RT, and
plotter numbers.
Peaks appear too slowly
Flow rate is too low.
Peaks appear too quickly
Flow rate is too high.
Battery life too short
Lamp power is too high. To get a status report,
press + . If "source power"
is greater than SO, see Corrective Procedure 1 in
Users Manual.
If cycle time is 2 minutes you are using frequent full
printout; battery life is reduced. Use external
battery pack (Cat. No. SA202) or minimize print
format.
Instrument uses carrier too fast
1. Flow rate is too high. Check flow rate.
2. Carrier gas is leaking. Tighten all fittings
(especially on column). Do not over tighten
valve fittings.
69
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Troubleshooting Guide for the Micromonitor: Supplement to SOP #2111
If the ready asterisk (*) won't come on, perform the
following:
1. Press the < METHOD > button. Note the
temperature setpoint for column A. Press the
button. Note the temperature setpoint
for column B.
2. Press the < STATUS > button. The display
should show the status at the same value as the
setpoint for B.
3. Press the button. The display should
show the status at the same value as the
setpoint for A.
4. Press the < ENTER > button. The display
should show a reading between 5 and 45 psig.
5. Press the button. The display should
show a reading in the same range of between 5
and 45 psig.
6. Press the < ENTER > button. The display
should show a reading between +420 mV and -
445 mV for the autozero voltage.
7. Press the button. The display should
still read in the above range.
8. If the temperatures are not correct, try waiting
until they heat up or cool down.
9. If the pressures are not correct, check the
supply or change the setting at the back.
10. If the autozero range is not correct, you may
have a slowly eluting peak coming through the
system.
11. Try increasing the temperature for a while to
purge the column.
70
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APPENDIX D
Figures
71
-------
72
-------
Figure 1: Pneumatics of Photovac 10S Series
SOP #2108
Nerewer 1967 ft-5f
Figure 6-1 PS50 PfEUWTKS - Wl flฃCTX3N
I'LUUI ซU
M XT
P*
CUT
(Skฐ)
ou. i ug i
OVEN
L0J
w
on
73
-------
74
-------
Figure 2: Micromonitor M200 Front Panel
SOP #2111
ฆ A COLUMN TEMPERATURE
UP
AUTO
START
METHOD
SAMPLE
PORT
GAS ONLY
A/B
ENTER
CONFIG
DOWN
REMOTE
RESET
STATUS
(ENTER KEYS)
(OPERATION KEYS)
(SET UP KEYS)
75
-------
76
-------
Figure 3: Systems Setup Diagram
SOP #2111
60 PSIG
TVQ STAGE
REGULATOR
99.995%
HEUUM
1/8' CARRIER
SUPPLY
1/16' INLET LINE
12 VOLT
SUPPLY
SAMPLE:
0-30 PSIG
77
-------
78
-------
Figure 4: Micromonitor M200 Back Panel
SOP #2111
r
0 ANALOG / CONTROL
ANALOG/CONTROL
SERIAL I/O
ฉC
~Je
ฉC
ฉ
0
0
COLUMN A
VENT
REFERENCE A
VENT
0
COLUMN A
PRESSURE
lฎ
0
0
SAMPLE
VENT
CARRIER
IN
ฉ
12 VOC
ฉ
COLUMN a
VENT
REFERENCE B
VENT
0
0
COLUMN B
PRESSURE
ฉ
0
0
79
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80
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Laboratories Complementary to Contract Laboratory Program (CLP).
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HNU Systems, Inc. 1975. Instruction Manual for Model PI101 Photoionization Analyzer.
Longbottom, J.E. and J. Lichtenberg. U.S. Environmental Protection Agency. 1982. Methods for Organic
Chemical Analysis of Municipal and Industrial Waste water, EPA Methods 601/602, EPA/600/4-82/057.
Overton, EJB., C. Steele, R. Sherman, E. Co Hard, S. McKinney, and T. McKinney. May, 1987. "Field Useable
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Subcommittee of the Joint Annv-Naw-NASA-Air Force Interagency Propulsion Committee. Cleveland.
OH.
Overton, E.B., T.H. McKinney, C.F. Steele, E.S. Collard, and R.W. Sherman. July, 1987. "Rapid Field Analysis
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Symposium on Solid Wastp. Testing and Quality Assurance. U.S.EPA, Washington, DC.
Overton, E.B., R.W. Sherman, E.S. Collard, P. Klinkhachorn, and H.P. Dharmasena. May, 1988. "Current
Instrumentation for Field Deployable Analysis of Organic Compounds", PiTftresdiPgs of the Joint Annv-
Naw-NASA-Air Force Safety and Environmental Protection Subcommittee Mutiny Monterey, CA.
Overton, E.B., R.W. Sherman, H.P. Dharmasena and C.F. Steele. June, 1988. "Remote Sensing Using Gas
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Field Screening Methods for Hazardous Waste Sif? f^ye^tiyatipn.: Las Vegas, NV.
Photovac 1QA10 Operations Manual. Photovac International, Thornhill, Ontario, Canada L3T 2L3.
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Qutokumpu X-MET 00 Portable SRF Analyzer Operating Instructions, Revision A, October 1989.
Sherman, R., T. McKinney, M. Solecki, R. Gaines, and B. Shipley. October, 1988. "Field Use of a Microchip
Gas Chromatograph", Prrvp^tin^ 0f the First International Symposium for Field Screwing Mpthrvk
ffflT Waste Sitp. Investigations Las Vegas, NV.
Sherman, R.W., M.K. Solecki, E.S. Collard, T.H. McKinney, L.H. Grande, and E.B. Overton. October, 1988.
"Development of a Held Portable Concentrator/Purge and Trap Device for Analysis of VOC in
Ambient Air and Water Samples", Pi-nrae-Hings of the. First International Symposium for Field Screening
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U.S. Code of Federal Regulations, 49 CFR Parts 100 to 177, Transportation, revised November 1, 198S.
81
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U.S. Environmental Protection Agency. 1984. Characterization of Hazardous Waste Sites - A Methods
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~ U.S. G.P.O.: 1992-.J11-893:60678 83
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