£ rPA United States m 0fficeof
\/Crr\ Environmental Protection Agency Research and Development
The Arizona Border Study
An Extension of the
Arizona National Human Exposure Assessment Survey (NHEXAS)Study
Sponsored by the Environmental Health Workgroup of the Border XXI Program
Quality Systems and Implementation Plan
for Human Exposure Assessment
The University of Arizona
Tucson, Arizona 85721
Cooperative Agreement CR 824719
Standard Operating Procedure SOP-BCO-L-31.0
Title: Analysis of Two-Phase Multisorbent Samplers for Volatile
Organic Compounds
Source: The University of Arizona
U.S. Environmental Protection Agency
Office of Research and Development
Human Exposure & Atmospheric Sciences Division
Exposure & Dose Research Branch
Notice: The U.S. Environmental Protection Agency (EPA), through its Office of Research and Development (ORD), partially funded
and collaborated in the research described here. This protocol is part of the Quality Systems Implementation Plan (QSIP)
that was reviewed by the EPA and approved for use in this demonstration/scoping study. Mention of trade names or
commercial products does not constitute endorsement or recommendation by EPA for use.
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Title: Analysis of Two-Phase Multisorbent Samplers for Volatile Organic Compounds
Document No. BCO-L-31.0
APPROVALS
1 Full SOP 1 Working SOP #pages 21
Issue Date: July 7, 1997
Revision No. 0
Revision No:
Revision Date:
Revision Made:
Revision No:
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Revision Made:
On Site Principal Investigator:
Project QA Director:
Independent Reviewer:
On Site PI:
Project QA Director:
Independent Reviewer:
On Site PI:
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Distributed To:
Revision No.
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2
3
4
5
6
Form TP-2
[07/10/97]
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Analysis of Two-Phase Multisorbent Samplers for Volatile Organic Compounds
1.0 Purpose and Applicability
This standard operating procedure (SOP) describes methodology for the analysis of
certain trace volatile organic compounds (VOCs) in air that are captured on two-phase
carbon-based multisorbent tubes packed with Carbotrap (graphitized carbon blacks) and
Carbosieve S-III (a carbon molecular sieve). The procedure involves thermal desorption
of the adsorbed species and their analysis by high-resolution gas chromatography (GC).
Table 1 provides a list of the NHEXAS primary compounds that are characterized using
this method.
Table 1. Compounds Fully Characterized or Only
Identified by GC/FID Analysis of Multisorbent Tubes.
Compound
Classification
Acetylene
Primary
Ethylene
Primary
Propene
Primary
Propane
Primary
Isobutane
Primary
1-Butene
Primary
n-Butane
Primary
2.0 Definitions
2.1 VOC: organic compound with saturation vapor pressure at 25°C between 10'2 and
10"8 kPa.
2.2 Two-phase multi-bed sorbent: carbon-based sorbent material used to collect C2 -
C4 VOCs in air.
2.3 Active sampler: tube packed with carbon-based sorbents used to collect air
samples for organic vapor analysis by drawing air at a known flow rate through
the tube using a pump.
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References
3.1 W.T. Winberry, Jr., N.T. Murphy, and R.M. Riggin, "Method TO-1: Method
for the Determination of Voaltile Organic Compounds in Ambient Air Using
Tenax® Adsorption and Gas Chromatography/Mass Spectrometry (GC/MS)," In:
Methods for Determination of Toxic Organic Compounds in Air: EPA Methods;
Noyes Data Corporation: Park Ridge, New Jersey, 1990.
3.2 "Standard Practice for Analysis of Organic Compound Vapors Collected by the
Activated Charcoal Tube Adsorption Method," Standard D 3687, American
Society for Testing and Materials, Philadelphia, PA, Annual Book of ASTM
Standards, 1989.
3.3 K.J. Krost, E.D. Pellizzari, S.G. Walburn, and S.A. Hubbard, "Collection and
Analysis of Hazardous Organic Emissions," Anal. Chem., 54, 810-817 (1982).
3.4 A.J. Pollack, S.M. Gordon, and D.J. Moschandreas. March 1993. Evaluation of
Portable Multisorbent Air Samplers for Use with an Automated Multitube
Analyzer. Report EPA/600/R-93/053, U.S. Environmental Protection Agency,
Research Triangle Park, North Carolina, 91 pp.
3.5 P. Ciccioli, A. Cecinato, E. Brancaleoni, M. Frattoni, and A. Liberti, "Use of
Carbon Adsorption Traps Combined with High Resolution Gas Chromatography-
Mass Spectrometry for the Analysis of Polar and Non-Polar C4-C14 Hydrocarbons
Involved in Photochemical Smog Formation," J. High Res. Chromatogr., 15, 75-
84(1992).
3.6 R.W. Bishop and R.J. Valis, "A Laboratory Evaluation of Sorbent Tubes for Use
with a Thermal Desorption Gas Chromatography-Mass Selective Detection
Technique," J. Chromatogr. Sci., 28, 589-593 (1990).
3.7 Varian 3600 GC Operator's Manuals, ND.
Discussion
4.1 Ambient air is drawn through a sampling tube. The sampling tube, containing the
sorbents Carbotrap and Carbosieve S-III, captures the VOCs in the air over the
range C2 - C4.
4.2 For analysis, the sampler is placed in a heated chamber and purged with an inert
gas (thermal desorption). The inert gas transfers the organic compounds from the
sorbent bed onto a cold trap and subsequently onto a gas chromatographic (GC)
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column which is held initially at a low temperature (-50°C). The GC column
temperature then is increased ("temperature-programmed") and the components
eluting from the column are identified and quantified using a flame ionization
detector (FID). Component identification is normally accomplished on the basis
of the GC retention time. For the present study, the VOCs of interest are those
listed in Table 1.
Responsibilities
5.1 Fixed-location sampling of indoor and outdoor air for the target VOCs will be
conducted by University of Arizona (UA) personnel as described in SOP
UA-F-11.1.
5.2 The Sample Custodian at Battelle will be responsible for receiving the samples
from UA and shall sign and date all forms accompanying the samples at the time
of sample receipt. The Sample Custodian shall also be responsible for
transferring custody of the samples to the appropriate Laboratory Analyst for
analysis and shall archive the remaining samples on completion of the laboratory
work.
5.3 Extraction, analysis, and calculations for the samples, as defined in this work
instruction, will be performed by the Laboratory Analyst in the Atmospheric
Sciences and Applied Technology Department at Battelle, under the direction of
the Laboratory Director or his/her designee.
5.4 The Data Coordinator shall be responsible for checking that the Laboratory
Analyst has completed the Sample Laboratory Data Sheet and for preparing Data
Packages for shipment to UA.
5.5 The Laboratory Director at Battelle will be responsible for ensuring completion of
the analyses in accordance with the work instruction and quality control
requirements. He/she will also be responsible for approving the original and
revisions to the method.
5.6 Any person who amends or alters this procedure is responsible for ensuring that
the changes have been properly documented, the SOP changed, reviewed, and
reissued.
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Materials and Reagents
6.1 Materials
6.1.1 Dynatherm Analytical Instruments, Inc Model 10 Tube Conditioner,
designed to accommodate Carbotrap 200 multibed sorbent sampler tubes.
6.1.2 50 m by 0.32 mm id fused silica PLOT column coated with Al203/NaS04.
6.1.3 Carbotrap 200 Stainless Steel Multi-Bed Thermal Desorption Tubes,
containing 70/80 mesh glass beads, 20/40 mesh Carbotrap B, and 60/80
mesh Carbosieve S-III, in lA" o.d. x 7" (18 cm) stainless steel.
6.1.4 Varian 3600 gas chromatograph (GC) equipped with a two-stage sorbent
trap and flame ionization detector (FID). With the FID, detection limits of
~0.3 ppbv are attainable.
6.1.5 Tylan mass flow controllers, with digital readout.
6.1.6 SKC constant flow sample pump.
6.1.7 Stopwatch.
6.1.8 Bubble flow meter, 25 mL.
6.1.9 Rotameter, 0-15 mL/min range.
6.1.10 Hamilton gas-tight syringes, 25-1000 jaL.
6.1.11 Low velocity laboratory fume hood.
6.1.12 Refrigerator.
6.1.13 Gas-phase dilution system.
6.1.14 Aadco clean air generator (or equivalent).
6.1.15 Nafion PermaPure tube (25 cm x 0.4 cm id).
6.1.16 Omega CN9000 Temperature Controller, used to control the temperature
of the Dynatherm tube desorber.
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6.1.17 15.7-L aluminum high-pressure gas cylinder.
6.1.18 Mechanical rotary-vane roughing pump.
6.2 Reagents
6.2.1 Helium carrier gas (purity 99.995%).
6.2.2 Liquid nitrogen (commercial grade).
6.2.3 Zero-grade nitrogen gas cylinder.
6.2.4 Gas cylinders of target gases (Matheson Gas Products) for preparation of
calibration standards.
7.0 Procedure
All relevant information relating to the analysis of samples, such as lot numbers,
manufacturers of reagents and gases, etc., must be recorded contemporaneously on the
"Sample Laboratory Data Sheet - Multisorbent/VOCs" (Figure 1) and compared against
any control parameters. Any deviations noted require that the analysis be discontinued or
justified via the analysts' best judgement.
7.1 Initial Preparations
7.1.1 Preparation of Target Compound Calibration Cylinder
7.1.1.1 Dilute calibration mixtures to calibrate the GC-FID system and
passive samplers are prepared from Standard Reference Materials
(SRM) from the National Institute of Standards and Technology
(NIST), if available. If not available, a calibration cylinder is
prepared in-house as follows.
7.1.1.2 Initially flush a 15.7-L aluminum cylinder with zero air, then
evacuate the container to -27 in. Hg with a roughing pump.
7.1.1.3 Since all of the target compounds listed in Table 1 are gases,
obtain a gas cylinder of each target gas.
7.1.1.4
Connect an injection port to the 15.7 L cylinder and turn on the
heater to the injection port.
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Using gloves and working at a fume hood, draw up 1 mL of each
of the target gases into a gas-tight syringe and then inject it into
the evacuated cylinder via the heated injection port.
Zero-grade air is directed through the injection port to aid in
sweeping each gas into the 15.7 L cylinder.
After all the gases have been injected, the injection port is
removed and the tank is pressurized with zero-grade N2 from a
high-pressure gas cylinder to 1,000 psig. The effective volume
of the gas in the cylinder is (1014.7 psia/14.7 psia) x 15.7 =
1,084 L.
The resulting concentrations for the primary target compounds
are listed in Table 2.
The cylinder and regulator are wrapped with heating tape and
maintained at 50°C to minimize sample adsorption.
Table 2. Concentrations of Target Compounds Prepared by
Injecting 1 mL of Each Pure Gas into Pressurized
15.7-L Cylinder.
Compound
Cylinder
Concentration
(ppbv)
Acetylene
920
Ethylene
920
Propene
920
Propane
920
Isobutane
920
1-Butene
920
n-Butane
920
7.1.1.10 To generate low ppbv (and pptv) concentrations for spiking the
sorbent tubes and for on-line instrument calibration, the
pressurized cylinder is attached to a gas phase dilutor.
7.1.1.11 Connect the Aadco air generator to the gas-phase dilutor to
obtain the diluent gas.
7.1.1.5
7.1.1.6
7.1.1.7
7.1.1.8
7.1.1.9
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7.1.1.12 Place aNafion PermaPure tube (25 cm x 0.4 cm ID), immersed
in distilled water, in line with the dilution system to humidify the
standard gas stream.
7.1.1.13 Measure the dilution air flow rate with a Tylan digital mass flow
controller and set the flow rate from the pressurized cylinder to
provide the dilution desired.
7.1.2 GC-FID Instrument Set-Up
7.1.2.1 The thermal desorption GC/FID system consists of a heated
thermal desorption chamber attached via a six-port valve to a
freeze-out loop, which is connected in turn to a capillary GC with
FID, and a data system. The thermal desorption module must be
able to accommodate the particular sampler tube configuration of
interest. Exposure of the sample to hot metal surfaces should be
minimized, and only stainless steel or nickel surfaces should be
used. The volume of the tubing and fittings leading from the
sampler tube to the GC column must be kept as small as possible
and all areas must be heated and well-swept by helium carrier
gas.
7.1.2.2 The GC must be equipped with subambient temperature
programming capability (using liquid nitrogen) to permit the use
of an initial oven temperature of-50°C.
7.1.2.3 Helium purge flow (through the sampler tube) and carrier gas
flow are set at approximately 36 mL/min and 1-2 mL/min,
respectively.
7.1.2.4 Once the column and other system components are assembled
and the various flows established, the column temperature is
initially increased to about 250°C for at least 4 hours to condition
the column.
7.1.2.5 The GC/FID data system is set according to the manufacturer's
instructions. Once the entire GC/FID has been set up, the system
is calibrated as described in Section 7.1.6. (Steps taken to
validate the operation of the data system are described in the
Appendix).
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7.1.3 Concentration of Target Compounds in Calibration Cylinder
7.1.3.1 The concentrations of the target compounds in the calibration
cylinder (Section 7.1.1) are determined by referencing it to a
primary standard from NIST that contains the compounds of
interest.
7.1.2.2 Measured volumes of the NIST primary standard and the
calibration cylinder are injected into the GC/FID system.
7.1.3.3 The response factors from the NIST primary standard are used to
determine the concentrations of the target compounds in the
calibration cylinder. These calculated concentrations are
assumed to apply to the standard cylinder.
7.1.4 Preparation of Calibration Standards and Spiked Laboratory/Field
Controls
7.1.4.1 Attach the pressurized standard cylinder and the Aadco air source
to the gas phase dilutor.
7.1.4.2 Establish a gas flow through the dilutor at the predetermined
concentration.
7.1.4.3 Attach a T-piece to the exit port of the gas phase dilutor.
7.1.4.4 Attach the multisorbent Carbotrap 200 sampler tube to an SKC
sample pump that has been adjusted to provide the desired flow
rate through the sampler tube.
7.1.4.5 Insert the sampler tube into the T-piece in the gas phase dilutor
and secure the Swagelok nut and ferrule.
7.1.4.6 Turn on the sample pump and sample the spiked stream until the
desired loading is achieved on the sample tube. Remove the
sample tube and place Swagelok caps on each end of the tube.
7.1.4.7 Designate a pre-determined number of spiked sampler tubes
(generally 10% of the number exposed in the field) as either
laboratory or field controls and handle accordingly.
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7.1.5 Calibration of the GC/FID System
7.1.5.1 Before analyzing a sample set, calibration runs are performed
with the Instrument Calibration Cylinder (Section 7.1.1), under
the same conditions used to analyze the field samples.
7.1.5.2 Calibration standards are used at four levels that bracket the
concentration range of interest.
7.1.5.3 For the present purposes, a linear response corresponds to a
correlation coefficient >0.98 for a linear least squares fit of the
concentration/area response data.
7.1.5.4 Once response linearity has been demonstrated, an intermediate
concentration standard near the expected levels for the
components of interest is used for daily calibration purposes.
7.1.5.5 Responses of the target compounds should not vary by more than
10% from day-to-day. If greater variability is observed, more
frequent calibration may be required to ensure the reliability of
the measurements.
7.1.5.6 For each analyte, the average retention time is established
manually from the individual retention times generated in the
calibration runs. A calibration response factor is determined for
the analyte by the computer.
7.1.5.7 The response for each target compound in the calibration
standard is used to calculate a response factor from the following
equation:
where RFC = response factor for component (ng injected/peak
area counts); Cc = concentration of component in calibration
standard (|ag/mL); Vj= volume of calibration standard injected
(mL); and Rc = component response in calibration standard
(peak area counts).
7.1.5.8 The RF values are tabulated and, provided the ratio of response
to concentration is a constant over the working range (<10%
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RSD), linearity through the origin may be assumed and the
average RF may be used in place of a calibration curve.
7.1.5.9 Experience with this system in the laboratory at Battelle has
shown that, once the initial calibration has been established, a
daily one-point calibration serves as a sufficient check of the
stability of the GCFID system.
7.1.5.10 After the single-point calibration, the analytical system is
challenged with a humidified zero air stream, using a clean
(blank) tube, to ensure the cleanliness of the system (i.e., levels
of target VOCs must be <0.2 ppbv).
Preparation of Field Samplers and Blanks for Analysis
Set up a new manila folder labeled with the date of analysis and place all
relevant information (written correspondence, identification of samples and
associated computer data files, GC/FID plots, etc.) in the folder. This file will
ultimately contain all information relating to the analysis and reports of the
samples analyzed in the laboratory this day.
7.2.1 Preparation of Carbotrap 200 Multisorbent Sampler Tubes
7.2.1.1 Arrange the Carbotrap 200 multisorbent sampler tubes in sets of
10 in the order that the samplers are recorded on the VOCs
Carbotrap 200 Sampler Analysis Data Sheet (Figure 2).
7.2.1.2 Inspect each sampler tube. If any defects, such as cracked caps,
etc., are observed, note them in the "Comments" column of the
Sampler Analysis Data Sheet.
7.2.1.3 If the cap is broken so that air may have entered the sampler, the
sample is voided and marked "NOT ANALYZED" in the
Sampler Analysis Data Sheet.
7.2.2 Preparation of Field Blanks
7.2.2.1 Of the samplers taken to the field, 10% are set aside as
unexposed field blanks and are analyzed with each set of
samples.
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7.2.2.2 Both laboratory blanks (unexposed samplers that remain in the
laboratory during sampling) and field blanks (unexposed
samplers sent into the field along with the samplers that are
exposed) are analyzed.
7.2.2.3 The amount of each target compound (in ng) collected on
exposed samplers must be corrected for the average amount
measured on the designated blanks. Generally, it is found that
properly conditioned carbon-based multisorbent tubes do not
produce background peaks above the detection limit.
7.2.2.4 A control chart of the amount of each target VOC on the
unexposed blanks will be kept with the VOCs/Carbotrap 200 Log
Book to ensure that there is no contamination of the sample
batches.
7.2.2.5 Blank samplers should show peaks that are no greater than 5 ng
per target compound. In practice, we find that clean sorbent
tubes show background peaks that are generally below the
detection limit.
Sampler Tube Analysis
7.3.1 For analysis of the sorbent tubes, an automated gas chromatographic
system equipped with cryogenic preconcentration is used. The automated
GC system incorporates a Varian 3600 GC with FID. A controller on the
Varian GC regulates the temperature of the cryogenic trap. A six port
valve is used to move the cryogenic trap between collection mode and
injection mode. The cryogenic trap is constructed of 20 cm x 0.2 cm ID
stainless steel tubing packed with sorbent material Carbotrap B and
Carbosieve S-III (Supelco). Target compounds are chromatographically
resolved with a 50 m x 0.32 mm id fused silica PLOT column coated with
Al203/NaS04. Optimum analytical results are achieved with this column
by holding the temperature at -50°C for two min, then temperature-
programming the GC oven from -50°C to 60°C at 20°/min, holding the
temperature at 60°C for one min, then temperature-programming to 200°C
at 10°/min. The column exit flow is directed to the FID.
7.3.2 Initially remove the Swagelok cap from the end of the sorbent tube and
place it in the Dynatherm desorber.
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7.3.3 The exhaust port of the Dynatherm desorber is attached to a PermaPure
Nafion drier. The drier then is attached to the heated transfer line (165°C)
from the automated GC/FID system.
7.3.4 Prior to desorbing the sorbent tubes, the cryogenic preconcentrator on the
GC/FID system is cooled to -40°C when a sorbent-based preconcentration
trap is used. The GC column is cooled to -50°C.
7.3.5 After placing the six-port valve in the FILL position to collect the
desorption products from the sorbent tubes, the Dynatherm desorber is
heated to 320°C with the Omega temperature controller for 10 min, with
36 mL/min of helium flow purging the heated sorbent tube.
7.3.6 Following the 10 min heated purge of the sorbent tube, the six-port valve
is moved to the INJECT position. The cryogenic trap then is heated to
between 150°C and 250°C while flushing the trap with helium. The
trapped compounds then are transferred to the Al203/NaS04 PLOT
column, and the GC oven temperature program is started along with the
FID data acquisition system.
7.3.7 After the final target compound elutes from the column, data acquisition is
terminated.
7.3.8 Once a stable baseline has been achieved, the system may be readied for
the next analysis.
7.3.9 Initial data processing generally involves quantification of each identified
component by integrating the peak area of a target compound and
comparing the value to that of the calibration standard.
7.3.10 Place all laboratory-related worksheets in the current analysis folder in
preparation for report generation.
Calculations
7.4.1 Calibration Curve
7.4.1.1 Data from calibration standards are used to calculate a response
factor for each target compound. Ideally, the process involves
analysis of at least three calibration levels of each component
during a given day and determination of the response factor
(area/ng injected) from the linear least squares fit of a plot of ng
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injected vs. FID Peak area. (In general, quantities of a
component greater than 1,000 ng should not be injected because
of the potential for column overloading and/or MS response
nonlinearity). A standard personal computer program is used to
fit a least squares regression equation of the form
Y = A + Bx
where Y = MS peak area (in area units, AU); x = level of the
target compound standard (ng); A = intercept, and B = slope
(AU/ng).
7.4.1.2 The correlation coefficient R2 must be greater than 0.98. If this
requirement is not met, re-evaluate the analysis and, if necessary,
run another calibration curve.
7.4.1.3 If substantial nonlinearity is observed in the calibration curve, a
nonlinear least squares fit should be used. This involves fitting
the data to the following quadratic equation:
Y - A + Bx + Cx2
where Y = MS peak area (in area units, AU); x = level of the
target compound standard (ng); A, B, and C = coefficients in the
equation.
7.4.2 Calculation of Target Compound Content of Blank or Control
Samplers
7.4.2.1 The target compound content of unexposed (blank) samplers or
control samples xun must be calculated using the calibration
coefficients from Section 7.4.1 and the measured peak areas of
the sample Yun for each compound of interest, i.e., for the linear-
response case, analyte quantities are calculated from the
equation:
x = ( ng)
un ^ \ <-> /
where xun = is the target compound content of the unexposed
sampler; and Yun = the associated peak area for the target
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compound from the unexposed sampler. For the nonlinear case,
the quantity of analyte is obtained from the equation:
Yun=A + BXun + Cxln
where A, B, and C = coefficients calculated from calibration
curve in Section 7.4.1.
7.4.3 Calculation of Target Compound Content of Exposed Samplers
7.4.3.1 Use the calibration coefficients from Section 7.4.1 and the
measured peak areas of the exposed sampler Yex for each
compound of interest and correct for the content of unexposed
samplers.
7.4.3.2 For the linear-response case:
ta-A , \
xa = ^\nS)
where ^ = is the target compound content of the exposed
sampler; and xu„ = the target compound content of the
unexposed samplers (from Section 7.4.2).
7.4.4 Calculation of Sorbent Sampler Target Compound Concentration
7.4.4.1 The concentration of each target compound in the original air
sample is calculated from the following equation:
C„ =
V*
where Cex = calculated concentration of the target compound
(ng/L); and Vair = total volume of air drawn through sampler
tube, at standard conditions (25°C and 760 mm of Hg). The total
volume Vair at standard conditions is calculated from the
equation:
V =V
air exP //
298
v760A273 + T
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where V tl = total volume sampled at measured temperature and
pressure (L); P = average barometric pressure (mm Hg); and T
= average ambient temperature (°C).
Quality Control
7.5.1 Calibration for Quantitative Analysis
7.5.1.1 Refer to the quantitative analysis calibration procedures in
Sections 7.1.5 and 7.1.6. If quantitative responses (in area
counts) of the lowest level standard mixture fall below the
detection limits, the instrument and/or GC column and injector
must be checked for performance degradation. The injector
should be cleaned or the first 0.5 m of the column should be
removed.
7.5.1.2 Those samples which were analyzed during the period when low
level standards were not detected will be reanalyzed.
7.5.3 Precision, Bias, and Detection Limit
7.5.3.1 Precision and bias are largely dependent upon the precision and
bias of the analytical procedure for each target compound, and
the precision and bias of the sampling process.
7.5.3.2 Precision also depends greatly on the chemical; for thermal
desorption introduction, repeatability is typically ± 20% at a 300
ng level.
7.5.3.3 Method Accuracy: Prior to conducting a study with the Carbotrap
200 tubes, blank tubes are spiked with the compounds of interest
and analyzed to determine the level of recovery of each compound.
Percent bias is given by:
X-Y
% Bias = ——-100
X.
where X= expected level of target compound; and Y= measured
level of target compound recovered in analysis. Recovery
efficiencies for the target compounds are between 80 and 120%.
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7.5.3.4 The limit of detection LOD for a target compound is obtained
from the above data. It is defined as:
LOD = A + 3.3cr
where A = intercept (coefficient) from linear or quadratic least
squares fit; and a = standard deviation of the lowest concentra-
tion measurements. The method detection limit is about 0.3
ppbv. This is equivalent to the injection of a 5 ng sample
collected from the passage of a 4 L air sample through a sorbent
tube, and assuming a molecular weight of 100 for a typical target
VOC. Both the range and limit of detection depend strongly on
the properties of the individual compounds of interest.
7.5.3.5 Blank Sorbent Tubes: One unused sorbent tube (not a field blank)
should be analyzed during each analytical study as a check on the
background contribution from the sampler tube.
Records
8.1 All operations, maintenance and performance calibration data are stored in each
instrument log book.
8.2 List each sample analyzed on the GC/FID in the instrument log book, including
the date of data acquisition, project number, instrument conditions, file name,
and removable diskette identification.
8.3 All analytical results are logged in specific project books and entered on the
Carbotrap 200 Sampler Analysis Data Sheet (Figure 2). Directions for filling out
the Analysis Data Sheet are as follows:
8.3.1 Obtain a separate Analysis Data Sheet for each sample.
8.3.2 In the spaces provided, enter the sample code, the analysis date, the
analyst's name, and the sample volume (in liters).
8.3.3 Enter the amounts obtained (in (ig) for the field sample and the blank.
8.4 All data files are stored on Bernoulli disks for permanent record.
8.5
Hardcopy output of chromatograms and data reports are generated by the data
system after each run.
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8.6 Hard copies of the data will be stored in the analytical laboratory with the
laboratory notebook.
8.7 Analysis results will be sent to UA after one-over-one review of the data.
8.8 All forms and logbooks shall also include the technician's signature, date, time of
analysis, and method number.
8.9 All completed data forms and results will be submitted to the Laboratory Director
where they will be checked and stored in a designated area.
8.10 All forms will be filled out in black ink. Any deletions or corrections shall be
made by drawing a line through the error and shall be initialed by the technician
making the correction.
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ITEM:
Sample Laboratory Data Sheet - Multisorbent/VOCs
PARAMETER:
Date
Analyst
Standard Curve Number
NIST Primary Gas Standard Lot No.
Date Approved
Calibration Gas Cylinder ID No.
Date Approved
Calibration Compounds Lot No.'s ON BACK
Helium Gas Cylinder ID No.
Date Approved
Nitrogen Gas Cylinder ID No.
Date Approved
GC Column ID No. Al203/NaS04, 50 m x 0.32 mm
Date Installed
GC Carrier Gas Flow Rate 1.0-1.2 cm3/min
GC Temperature Program -50°C hold for 2 min, -50°C -
Thermal Desorber Cycle
Standard Curve Slope Value
Intercept
Regression R2
60°C at 20°/min, hold at 60°C
for 1 min, 60°C - 200°C at
107min
320°C for 10 min with pre-
concentrator at -40°C and 36
mL/min He purge
XXX-XXY
YYY - YYZ
>0.98
No. of Cartridges Analyzed
No. of Monitors Recorded
COMMENTS:
SAME AS ANALYZED
Figure 1. Example of Sample Laboratory Data Sheet - Multisorbent/VOCs.
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Sample Laboratory Data Sheet - Multisorbent/VOCs (continued)
COMPOUND
LOT NO.
DATE APPROVED
MANUFACTURER
Acetylene
Ethylene
Propene
Propane
Isobutane
1 -Butene
n-Butane
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Carbotrap 200 Sampler Analysis Data Sheet
Sample ID: Date:
Active Sampling Time: min Sample Volume, V = L
Compound
Amount, ^g
MDL, (ig
Acetylene
Ethylene
Propene
Propane
Isobutane
1-Butene
n-Butane
Figure 2. Example of Carbotrap 200 Sampler Analysis Data Sheet.
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Appendix
Data System Validation
We have adopted a "holistic" approach to validate the computer system used in
this SOP, based on the procedure described by Furman et al. (W.R. Furman, T.P.
Layloff, and R.E, Tetzlaff, "Validation of Computerized Liquid Chromatographic
Systems," J. AOAC Intl., 77, 1314-1318, 1994). This consists of tests to measure
and evaluate the performance of the entire computerized GC-FID system under
the conditions of its intended use, namely, the analysis of multisorbent samplers
for VOCs.
The approach involves an initial characterization and calibration, and a running
calibration. The initial characterization consists of identifying the peak retention
times for the target compounds. The initial calibration is designed to evaluate
system linearity and precision. Linearity is determined by using at least 4
standard mixtures to generate the response curve over the range of interest, as
specified in the SOP. Precision is determined initially by making replicate
injections (> 5) of a single standard mixture and calculating the standard deviation
of the area responses.
After satisfactory linearity and precision data are obtained, a standard mixture is
run at regular intervals so as to document that the system is not drifting or has
undergone an unexpected change.
All data generated in evaluating the characterization of spectra and calibration of
the system are maintained in a documentation file that is kept with the instrument.
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