EPA/600/R-12/046 | July 2012 | www.epa.gov/ord
United States
Environmental Protection
Agency
Technology Evaluation Report
GE Analytical Instruments
Sievers® 900 Portable Total
Organic Carbon Analyzer
1 \
j 900
Office of Research and Development
National Homeland Security Research Center
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Technology Evaluation Report
GE Analytical Instruments
Sievers®900
Portable Total Organic Carbon (TOO)
Analyzer
United States Environmental Protection Agency
Cincinnati, Ohio, 45268
11
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Contents
Notice v
Foreword vi
Acknowledgements vii
Abbreviations/Acronyms viii
Executive Summary ix
1.0 Introduction 1
2.0 Technology Description 2
3.0 Experimental Details 3
3.1 Portable Pipe Loop and Experimental Setup 3
3.2 Baseline Conditions 4
3.3 Portable Pipe Loop (PPL) Contaminant Injections 5
3.4 Discrete Sample Analysis 7
3.5 Contaminant Concentrations 7
3.6 Data Analysis 8
4.0 Quality Assurance/Quality Control 11
4.1 Reference Method 11
4.2 Instrument Calibration 11
4.3 Audits 12
4.4 Quality Assurance/Quality Control (QA/QC) Reporting 14
5.0 Evaluation Results 15
5.1 Toxic Industrial Chemicals (TICs) in Drinking Water 15
5.2 Biological Contaminants (BCs) in Drinking Water 22
5.3 Discrete Sample Analyses 27
5.4 Additional Tests 30
5.5 Operational Characteristics 32
6.0 Performance Summary 35
6.1 900 Portable Response to Contaminant Injections 35
6.2 Accuracy of 900 Portable Measurements 36
6.3 Operational Characteristics 36
7.0 References 37
Figures
Figure 2-1. 900 Portable 2
Figure 3-1. EPA's Portable Pipe Loop 4
Figure 5-1. Change in 900 Portable Total Organic Carbon (TOC) in response to
injections of colchicine 16
Figure 5-2. Change in 900 Portable Total Organic Carbon (TOC) response to injections
of Bacillus globigii 22
in
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Tables
Table 3-1 Source and Purity of Contaminants 6
Table 3-2. Contaminant List 9
Table 4-1. Summary of Total Organic Carbon Reference Method 11
Table 4-2. Performance Evaluation Audit Results 12
Table 5-1. Change in 900 Portable Total Organic Carbon (TOC) from Injections of
Toxic Industrial Chemicals (TICs) into Chlorinated Water 17
Table 5-2. Change in 900 Portable Total Organic Carbon (TOC) from Injections of
Toxic Industrial Chemicals (TICs) into Chloraminated Water 18
Table 5-3. 900 Portable Accuracy for Toxic Industrial Chemicals (TICs) in Chlorinated
Water 20
Table 5-4. 900 Portable Accuracy for Toxic Industrial Chemicals (TICs) in
Chloraminated Water 21
Table 5-5. Change in 900 Portable Total Organic Carbon (TOC) from Injections of
Biological Contaminants (BCs) into Chlorinated Water 23
Table 5-6. Change in 900 Portable Total Organic Carbon (TOC) from Injection of
Biological Contaminants (BCs) into Chloraminated Water 24
Table 5-7. 900 Portable Accuracy for Biological Contaminants (BCs) in Chlorinated
Water 25
Table 5-8. 900 Portable Accuracy for Biological Contaminants (BCs) in Chloraminated
Water 26
Table 5-9. Change in 900 Portable Total Organic Carbon (TOC) for Discrete Sample
Analyses in Chlorinated Water 27
Table 5-10. Change in 900 Portable Total Organic Carbon (TOC) for Discrete Sample
Analyses in Chloraminated Water 28
Table 5-11. 900 Portable Accuracy for Discrete Sample Analyses in Chlorinated Water
30
Table 5-12. 900 Portable Accuracy for Discrete Sample Analyses in Chloraminated
Water 30
Table 5-13. Change in 900 Portable Total Organic Carbon (TOC)with Elevated Total
Organic Carbon (TOC) Concentrations 31
Table 5-14. Change in 900 Portable Total Organic Carbon (TOC) with Elevated Ionic
Strength 31
IV
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Notice
The U.S. Environmental Protection Agency (EPA), through its Office of Research and
Development's National Homeland Security Research Center, funded and managed this
technology evaluation through a Blanket Purchase Agreement under General Services
Administration contract number GS23F0011L-3 with Battelle. This report has been peer
and administratively reviewed and has been approved for publication as an EPA
document. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use of a specific product.
Questions concerning this document should be addressed to:
Shannon Serre
National Homeland Security Research Center
Office of Research and Development
U.S. Environmental Protection Agency
109 T.W. Alexander Drive, E343-01
Research Triangle Park, NC 27711
919-541-3817
serre.shannon@epa.gov
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Foreword
The U.S. Environmental Protection Agency (EPA) is charged by Congress with
protecting the nation's air, water, and land resources. Under a mandate of national
environmental laws, the Agency strives to formulate and implement actions leading to a
compatible balance between human activities and the ability of natural systems to support
and nurture life. To meet this mandate, the EPA's Office of Research and Development
(ORD) provides data and science support that can be used to solve environmental
problems and to build the scientific knowledge base needed to manage our ecological
resources wisely, to understand how pollutants affect our health, and to prevent or reduce
environmental risks.
In September 2002, EPA announced the formation of the National Homeland Security
Research Center (NHSRC). The NHSRC is part of the Office of Research and
Development; it manages, coordinates, supports, and conducts a variety of research and
technical assistance efforts. These efforts are designed to provide appropriate, affordable,
effective, and validated technologies and methods for addressing risks posed by
chemical, biological, and radiological terrorist attacks. Research focuses on enhancing
our ability to detect, contain, and decontaminate in the event of such attacks.
NHSRC's team of world renowned scientists and engineers is dedicated to understanding
the terrorist threat, communicating the risks, and mitigating the results of attacks. Guided
by the roadmap set forth in EPA's Strategic Plan for Homeland Security, NHSRC ensures
rapid production and distribution of security-related products.
The NHSRC has created the Technology Testing and Evaluation Program (TTEP) in an
effort to provide reliable information regarding the performance of homeland security
related technologies. TTEP provides independent, quality assured performance
information that is useful to decision makers in purchasing or applying the tested
technologies. It provides potential users with unbiased, third-party information that can
supplement vendor-provided information. Stakeholder involvement ensures that user
needs and perspectives are incorporated into the test design so that useful performance
information is produced for each of the tested technologies. The technology categories of
interest include detection and monitoring, water treatment, air purification,
decontamination, and computer modeling tools for use by those responsible for protecting
buildings, drinking water supplies and infrastructure, and for decontaminating structures
and the outdoor environment. Additionally, environmental persistence information is
important for containment and decontamination decisions.
The evaluation reported herein was conducted as part of the TTEP program. Information
on NHSRC and TTEP can be found at http://www.epa.gov/nhsrc/ttep.html.
VI
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Acknowledgements
Contributions of the following individuals and organizations to the development of this
document are acknowledged:
United States Environmental Protection Agency (EPA)
Shannon Serre, Task Order Project Officer
Jeff Szabo
Matthew Magnuson
Mike Henrie
New York City Department of Environmental Protection
Yves Mikol
vn
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Abbreviations/Acronyms
BC
BSL
cm
%D
EPA
L
m
m/s
mg/L
NHSRC
PBS
PE
PPL
QA
QMP
SCADA
SOP
T&E
TIC
TOC
TSA
TTEP
UVS
%U
biological contaminant
biological safety level
centimeter
percent difference
U.S. Environmental Protection Agency
liter
meter
meter per second
milligram per liter
National Homeland Security Research Center
phosphate buffered saline
performance evaluation
portable pipe loop
quality assurance
quality management plan
supervisory control and data acquisition
standard operating procedure
testing and evaluation
toxic industrial chemical
total organic carbon
technical systems audit
Technology Testing and Evaluation Program
ultraviolet spectrometers
experimental uncertainty
microgram per liter
Vlll
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Executive Summary
The U.S. Environmental Protection Agency's (EPA's) National Homeland Security
Research Center (NHSRC) Technology Testing and Evaluation Program (TTEP) is
helping to protect human health and the environment from adverse impacts resulting from
acts of terror by carrying out performance tests on homeland security technologies.
Under TTEP, the performance of several online total organic carbon (TOC) analyzers and
ultraviolet spectrometers (UVS) was evaluated. The primary objective of this series of
evaluations was to determine the response of the TOC analyzers and UVSs upon the
introduction of contaminants such as toxic industrial chemicals and biological
contaminants into drinking water. This report describes the evaluation of the Sievers®
900 Portable TOC Analyzer (GE Analytical Instruments, Boulder, Colorado), hereafter
referred to as the 900 Portable. The 900 Portable was operated in conjunction with
EPA's portable pipe loop (PPL), which was designed to simulate a drinking water
distribution system. Investigators injected 14 different contaminants into both chlorinated
and chloraminated water and observed the change in the TOC measurement. For the
purposes of this study, a "response" (i.e., an anomalous change) was identified as a post-
injection change in TOC measurement that must exceed at least three times the standard
deviation of the baseline TOC level for the 30 minutes prior to and after the contaminant
injection. Relatively low contaminant concentration levels (0.01 - 10 mg/L) were
selected because many of the contaminants pose health risks at low drinking water
concentrations. In addition, to evaluate the accuracy of the 900 Portable, measurements
of TOC were made daily using a laboratory reference method and compared with the
results from the 900 Portable. Deployment and operational factors were also documented
and reported.
900 Portable Responses to Contaminant Injections
Investigators injected the contaminants aldicarb, carbofuran, colchicine, diesel fuel,
disulfoton, mevinphos, nicotine, potassium cyanide, sodium fluoroacetate, Bacillus
globigii, Bacillus thuringiensis, Chlorella, ovalbumin, and ricin for testing. The
contaminant injection solutions were prepared within 24 hours (most within 8 hours) in
the same water that was within the PPL. Since this water contained disinfectants it could
cause degradation or transformation of the contaminants prior to injection. The 900
Portable responded to all three replicate injections of col chi cine and nicotine at
concentrations from 0.1 mg/L-10 mg/L in both chlorinated and chloraminated water. In
chlorinated water, aldicarb was detected in two of three injections at 0.1 mg/L and
carbofuran was detected in one of three injections at 0.1 mg/L. In chloraminated water,
aldicarb and carbofuran were both detected in one of three injections at 0.1 mg/L. All of
IX
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the toxic industrial chemicals were detected during every injection at 1 mg/L and above
(if injections were performed) with the exception of potassium cyanide which was only
once detected at 1 mg/L in chlorinated and in chloraminated water, but was detected in all
the 10 mg/L injections into both water matrices. The 900 Portable did not respond to
injections of Bacillus globigii or Chlorella at any injected concentration. Bacillus
thuringiensis produced a response at 107 organisms/L for a mixture of spores and
vegetative cells in both chlorinated and chloraminated water. Ovalbumin produced a
response for all injections at 0.1 mg/L, 1 mg/L, and 10 mg/L in chlorinated water and in
chloraminated water produced a response for one injection at 0.1 mg/L and all injections
at 1 mg/L and lOmg/L. Disulfoton, diesel fuel, and ricin were analyzed only as discrete
samples. For these contaminants, the 900 Portable detected a change in TOC in response
to 0.1 and 1 mg/L of carbofuran in both water matrices. Although diesel fuel was
insoluble, it was added to water and analyzed using the 900 Portable. The results,
however, were inconsistent and difficult to interpret. Disulfoton caused a response at 1
mg/L in both water matrices and ricin caused a response at 1 and 10 mg/L. In addition to
these measurements, limited experiments were performed to examine the effect of
elevated TOC, ionic strength, and monochloramine concentrations on the 900 Portable
TOC measurements.
Accuracy of 900 Portable Measurements
The TOC measurements from the 900 Portable were compared with those from a
commonly used reference method and instrument during all of the contaminant injections
performed during the evaluation. These comparisons should be interpreted with the
awareness that different TOC instruments and oxidation methods can respond differently
to various contaminants. Overall, the average absolute value of the percent difference
(%D)between the 900 Portable and the reference method for all the comparisons across
the evaluation was 17% plus or minus (±) a standard deviation (SD) of 7%. For toxic
industrial chemicals (TICs) the %D averaged 15% ± SD 5% and 14% ± SD 8%, for
chlorinated and chloraminated water, respectively. For the biological contaminants, the
%D averaged 19% ± SD 3% and 15% ± SD 6%, for chlorinated and chloraminated water,
respectively. For each individual comparison, the experimental error was propagated
using the uncertainty of both measurements and is reported. Throughout the evaluation
of the 900 Portable, the propagated experimental uncertainty was typically small with
respect to %D. There were only a few instances when the %D did not result in a major
difference between the 900 Portable and the reference method.
Operational Characteristics
During the evaluation of the 900 Portable, general operational characteristics were
observed. Installation and operation of the 900 Portable was straight forward and clearly
articulated by the vendor during a one day visit. Operation of the 900 Portable using the
touch screen on the front panel was simple and intuitive. Evaluation staff initiated tests
by pressing one button, they downloaded data by following on-screen prompts, and they
replaced reagents and the ultra-violet (UV) lamp by following the instruction manual.
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The front panel of the 900 Portable provided messages to prompt the user to initiate
maintenance tasks. In this evaluation, where individual experiments lasted approximately
one day, the data from the 900 Portable were easily retrieved and were provided in a text
delimited format enabling export into a spreadsheet. This evaluation did not consider
other possible data retrieval methods (e.g. supervisory control and data acquisition
[SCADA]) that could be utilized with the 900 Portable.
XI
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1.0 Introduction
The U.S. Environmental Protection Agency's (EPA) National Homeland Security
Research Center (NHSRC) is helping to protect human health and the environment from
adverse impacts resulting from intentional acts of terror. With an emphasis on
decontamination and consequence management, water infrastructure protection, and
threat and consequence assessment, NHSRC is working to develop tools and information
that will help detect the intentional introduction of chemical or biological contaminants
into buildings or water systems, the containment of these contaminants, the
decontamination of buildings and/or water systems, and the disposal of material resulting
from clean-ups.
NHSRC's Technology Testing and Evaluation Program provides high-quality
information that is useful to decision makers in purchasing or applying the evaluated
technologies. It provides potential users with unbiased, third-party information that can
supplement vendor-provided information. The Technology Testing and Evaluation
Program (TTEP) works in partnership with recognized testing organizations, with
stakeholder groups consisting of buyers and users of homeland security technologies, and
with the participation of individual technology developers, in carrying out performance
testing. Stakeholder involvement ensures that user needs and perspectives are
incorporated into the evaluation design so that useful performance information is
produced for each of the evaluated technologies. The program evaluates the performance
of innovative homeland security technologies by developing evaluation plans that are
responsive to the needs of stakeholders, conducting tests, collecting and analyzing data,
and preparing peer-reviewed reports. All evaluations are conducted with rigorous quality
assurance (QA) protocols to ensure that data of known and high quality are generated and
that the results are defensible.
Under TTEP, the performance of the Sievers® 900 Portable Total Organic Carbon
Analyzer (GE Analytical Instruments, Boulder, Colorado), hereafter referred to as the
900 Portable was evaluated. The primary objective of this evaluation was to determine
the ability of the 900 Portable to detect changes in the total organic carbon (TOC)
concentration in response to the introduction of contaminants into drinking water. Two
other objectives were to evaluate the accuracy of the TOC measurement and to document
deployment and operational characteristics. This evaluation was conducted according to
a peer-reviewed test/QA plan(1) that was developed according to the requirements of the
TTEP quality management plan (QMP) and associated amendments.^
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2.0 Technology Description
This report provides results for the evaluation of the 900 Portable. A description of the
900 Portable based on information provided by the vendor follows.
Figure 2-1 shows the 900 Portable as configured for
this evaluation. The 900 Portable consisted of a
portable analyzer with all analysis, control, data
storage, and data visualization capabilities
integrated into one package. The enclosure for the
900 Portable was 23 centimeters (cm) wide, 48 cm
deep, and 36 cm tall.
The 900 Portable measures TOC and, while not
used during this evaluation, has the capability to
measure total inorganic carbon and total carbon.
The 900 Portable oxidizes organic compounds using
UV radiation and a chemical oxidizing agent,
ammonium persulfate, to form carbon dioxide.
Carbon dioxide is measured using a selective
membrane-based conductometric detection
technique. As configured for this evaluation, a
separate inorganic carbon removal module was
Figure 2-1. 900 Portable
included with the 900 Portable.
All data collection and storage is integrated into the 900 Portable package. Analysis
results are displayed in a chart on the front panel as they are collected. Data can be
downloaded using either an USB or serial connection. Data files from the 900 Portable
are stored as comma delimited text.
The 900 Portable requires two reagents, an acid and an oxidizer. These reagents are
housed within the enclosure and must be changed as needed (typically six months for the
acid and three months for the oxidizer). The UV lamp must be replaced every six
months. The total cost of the 900 Portable as configured for this evaluation is $22,800.
(There is a non-portable version of the same instrument that costs $21,900 and has two
customizable alarm outputs that can be triggered if the measured TOC exceeds a set
value.) The estimated yearly non-labor operation and maintenance costs are expected to
be approximately $2,400 including such items as the reagents and the ultraviolet lamp.
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3.0 Experimental Details
The primary objective of this series of evaluations was to determine the capability of
TOC analyzers and ultraviolet spectrometers (UVSs) to measure changes in TOC level
due to the introduction of contaminants into drinking water. Four technologies, two TOC
analyzers and two UVSs, were evaluated. Two drinking water matrices were used for all
of the testing conducted in this evaluation: (1) finished drinking water from Columbus,
Ohio (chlorinated and filtered surface water), and (2) water prepared to simulate water
from a utility that uses chloramination as its primary means of disinfection. Eleven
contaminants were injected using the EPA's portable pipe loop (PPL) and four
contaminants were analyzed using a discrete analysis approach.
This series of evaluations took place between June 3, 2009 and September 24, 2009. The
contractor and EPA provided QA oversight of this evaluation. The contractor QA staff
conducted a technical systems audit (TSA) and an audit of data quality.
3.1 Portable Pipe Loop and Experimental Setup
This series of evaluations was conducted using EPA's Portable Pipe Loop (PPL), which
is shown in Figure 3-1. The PPL consists of: (1) an equipment rack that contains a 78
liter (L) stainless steel mixing tank, a recirculating pump, a peristaltic pump, and three
contaminant injection ports; and (2) a piping rack that contains approximately 29 meters
(m) of 7.6 cm diameter stainless steel pipe (316L grade). The two racks were connected
for the evaluation. All four TOC analyzers and UVSs evaluated were connected to the
PPL by one of the eight separate sample ports with 6.35 millimeter (mm) (or one quarter
inch) inner diameter tubing.
The variable flow recirculating pump controlled PPL flow which allowed the operator to
set flow rates from 44 to 440 liters/minute (L/min) in the PPL. For testing, the PPL
contained approximately 250 L of water (including the mixing tank and pipe) with a flow
rate of approximately 88 L/min (linear velocity of 0.33 m/s). Because of the addition of
reagents to the water, the water sampled by the two TOC analyzers was discharged to a
waste container after analysis.
When evaluating several technologies simultaneously, an adequate flow of water must be
maintained to supply each of the technologies. The 900 Portable sampled a 2.5 milliliter
sample from the flowing water every 4 minutes. Excess sample flow and waste from the
900 Portable were combined and then collected into a waste container.
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Figure 3-1. EPA's portable pipe loop
3.2 Baseline Conditions
Prior to the start of daily testing, investigators filled the PPL with drinking water using a
hose (15.9 mm or 5/8" ID) and a hose-thread to sanitary-fitting coupler that connected the
laboratory water supply to the PPL mixing tank. During the chlorinated water testing,
this water was used with no alterations after the free chlorine level was measured using
/o\
U.S EPA Method 330.5. ; Over the course of the evaluation, free chlorine
concentrations in the chlorinated water ranged from 1.0 to 1.6 mg/L with an average of
1.3 mg/L. The pH of the water was between 7.4 and 8.1.
The chloraminated test water matrix was prepared by mixing chlorine and ammonia in
the proper ratio to yield approximately 2 mg/L monochloramine, following an EPA
Testing & Evaluation (T&E) Facility standard operating procedure (SOP) for preparation
of chloraminated water.(3) Investigators measured the total chlorine concentration and
then added chlorine to the PPL to increase the total chlorine concentration to 2 mg/L.
The total chlorine concentration was then measured again to confirm the total chlorine
concentration was within 10% of 2 mg/L. Ammonia was then added to the PPL to form
monochloramine at a concentration of 2 mg/L in the PPL. Prior to the injection of a
contaminant, the monochloramine concentration was confirmed using Hach
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Method 10200^. Throughout the evaluation, the monochloramine concentrations
ranged from 1.8 to 2.3 mg/L with an average of 2.0 mg/L.
Once investigators completed the applicable chlorine measurement, they conducted a 30
minute baseline measurement using the 900 Portable. During this baseline measurement
period, a reference sample was collected from an unoccupied PPL sampling port. The
reference sample was collected by flushing approximately 500 mL of water from the
sampling port into a waste container and then collecting two separate 40 mL vials of
sample. The reference samples were immediately preserved by acidification with
phosphoric acid. Reference samples were analyzed daily on the TOC reference
instrument which was housed in the same laboratory as the PPL. The reference TOC
results were used to evaluate the accuracy of the TOC measurements from the 900
Portable.
3.3 Portable Pipe Loop (PPL) Contaminant Injections
The toxic industrial chemicals (TICs) and biological contaminants (BCs) were injected
into the PPL as concentrated 250 mL solutions. These solutions were prepared within 8
hours of injection (with the exception of the discrete samples which were prepared the
day before) using the same water used to fill the PPL, either chlorinated or
chloraminated. The preparation of contaminant injection solutions with water containing
disinfectants could cause degradation or transformation of the contaminant. For example,
the interaction of the cyanide ion with chlorinated water could have formed cyanogen
chloride which continued to breakdown to the cyanate ion. These reactions are
dependent on the water quality of the dissolution water so the results presented here
should be interpreted carefully and not broadly extrapolated. However, the experimental
plan was intended to simulate an actual contamination event during which the use of tap
water as the dissolution solvent would be expected. In addition, degradation of organic
carbon drinking water is not likely so, for the 900 Portable, the presence of a contaminant
could still be measured.
Table 3-1 shows the sources of each TIC and toxin contaminants and their purity. The
purity of the TICs varied substantially from 89% to 99%. Information about the content
of the impurities for each contaminant was not available so the impurities could have
contained organic carbon. In addition, aldicarb, carbofuran, and disulfoton were difficult
to dissolve and required gentle heating to encourage them into solution. Heating these
solutions could have favored transformations thereby preventing the stated contaminant
(and instead transformational product) from being injected into the PPL.
Originally, the two Bacillus species were grown in nutrient broth while the Chlorella was
grown in Bold 1NV Medium*-9-*. The final BC cultures were pelleted by centrifugation
and washed in PBS three times. The washed pellet cake was then resuspended in
phosphate buffered saline (PBS). The BC solution was enumerated and injection
solutions were prepared by diluting the BC to the appropriate concentrations in PBS. The
concentration of each injection solution was such that injection of 250 mL of the solution
into 250 L of water in the PPL gave the desired steady-state concentration in the PPL.
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Table 3-1 Source and Purity of Contaminants
Contaminant
Aldicarb
Carbofuran
Colchicine
Diesel
Disulfoton
Mevinphos
Nicotine
Ovalbumin
Potassium Cyanide
Ricin
Sodium Fluoroacetate
Sodium Fluoroacetate
Supplier
Ultra Scientific (North Kingston, RI)
Sigma-Aldrich (St. Louis, MO)
Sigma-Aldrich (St. Louis, MO)
Marathon (Columbus, OH)
Chem Service (West Chester, PA)
Ultra Scientific (North Kingston, RI)
Acros Organics (Geel, Belgium)
MP Biomedicals (Solon, OH)
Sigma-Aldrich (St. Louis, MO)
Vector Laboratories (Burlingame, CA)
Sigma-Aldrich (St. Louis, MO)
Pfaltz & Bauer (Waterbury, CT)
Purity
99%
98%
97%
Retail-grade (from pump)
98.7%
89.4%
98%
98%
96%
5 mg/mL (in phosphate
buffered sodium azide)
99%
95%
Upon establishing a steady response in the PPL and collecting a minimum of 30 minutes
of baseline data, a series of single contaminant injections was made into the circulating
water of the PPL. With each injection, the concentration of the contaminant at any point
within the PPL changed until a steady-state concentration for the contaminant was
reached. As the contaminant stock solution was introduced into the intake side of the
recirculating pump of the PPL, the initial contaminant "slug" made a first pass by the 900
Portable intake. The contaminant concentration within the slug was higher than the
eventual steady-state contaminant concentration within the PPL. As the contaminant slug
flowed throughout the PPL, it entered the mixing tank, became greatly diluted, and then
recirculated until, within about 10 minutes, a steady-state concentration was reached.
This evaluation focused on the steady-state concentration reached in the PPL after
mixing. The mixing time of approximately 10 minutes and the measurement frequency
of 4 minutes prevented the initial contaminant slug through the PPL from being measured
by the 900 Portable TOC. However, in an operational setting, the 900 Portable would be
able to measure continuous changes in TOC as long as the changes being measured lasted
for at least four minutes.
Starting with the lowest concentration level for each contaminant, the contaminant
injection solution was pumped into the circulating water of the PPL at a rate that made
the concentration of the contaminant 10 times greater than the eventual steady-state
concentration in the water moving past 900 Portable. This injection lasted for 15-20
seconds, which at a flow rate of 88 L/min (linear velocity of 0.33 m/s) corresponds to
approximately a 4.5 m long (-25 L) slug of injected contaminant at the desired
concentration.
A steady-state TOC concentration was reached in the PPL approximately 10 minutes
after the contaminant injection. To ensure that the contaminant concentration had
reached steady-state, investigators allowed a 20 minute stabilization period after a
contaminant injection. After this 20 minute stabilization period, 30 minutes of data from
each instrument were collected at the post-injection steady-state concentration. In
addition to being used to determine the steady-state response for each instrument, these
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30 minutes of data were used as the baseline for the next contaminant injection. The next
higher concentration level of contaminant was introduced using an identical procedure.
Therefore, a minimum of 50 minutes passed between contaminant injections. One
reference sample was collected when the PPL reached the steady-state concentration
following each contaminant injection. A duplicate sample was taken for one reference
sample during each day of testing.
Each set of contaminant injections with increasing concentration levels (some
contaminants had three concentration levels, some had four concentration levels)
represented one replicate. Three replicate sets of injections were made for each
contaminant. Between the replicate sets of injections, the PPL system was exchanged at
least five times with contaminant-free water (from the laboratory supply). As this
uncontaminated water filled the PPL, the online measurements returned to the original
baseline. Once five water exchanges had been completed (approximately 30 minutes of
water exchange) and the response from each technology steadied so it deviated from the
average by less than 10% over 30 minutes, testing proceeded with the next replicate set of
injections for that contaminant.
3.4 Discrete Sample Analysis
Three contaminants (diesel fuel, disulfoton, and ricin) were analyzed with the 900
Portable solely as discrete samples rather than injections into the PPL. PPL use was
precluded for ricin because it must be contained within a biosafety hood. Disulfoton was
added to the experimental plan in the same test/QA plan amendment as ricin and was
analyzed in the same fashion. Diesel fuel was analyzed discretely out of concern that it
would contaminate the PPL. Carbofuran was analyzed discretely and also with the PPL
so that one contaminant would be analyzed using both experimental approaches. For the
discrete samples, investigators prepared 40 mL vials of chlorinated and chloraminated
water contaminated to the desired concentration along with vials of uncontaminated
water. In grab sample mode, the 900 Portable analyzed four samples from the same vial
and reported the concentration as the average of the final three measurements. Following
analysis of the uncontaminated water samples, the 900 Portable analyzed the vial
containing the lowest contaminant concentration. This process was repeated for all
concentrations measured. Three vials of each concentration were analyzed as discrete
samples.
The 0.01 mg/L contaminant concentration was not evaluated by discrete analysis. In
addition, due to poor solubility, disulfoton and carbofuran were not analyzed at 10 mg/L
as discrete samples. Diesel fuel was insoluble in water and separated upon mixing with
water, but discrete sample analyses at 10 mg/L were still performed.
3.5 Contaminant Concentrations
Table 3-1 gives the injected contaminants and their corresponding concentrations. As
described in the test/QA plan(1), TIC injection concentrations were selected based on
previous testing performed at EPA's Testing and Evaluation (T&E) Facility(4) BC
injection concentrations were based on relevant toxicological data (e.g., infective dose)*-5-*
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as well as concentrations recommended by TTEP water security stakeholders. The 0.01
mg/L contaminant solutions were injected into the PPL during the evaluation and the
results reported for the 900 Portable. However, 0.01 mg/L is very near the detection limit
of the 900 Portable. Therefore, because the contaminants being injected contained both
organic and inorganic carbon, detectable results for TOC were not necessarily expected
for the 0.01 mg/L concentration level.
3.6 Data Analysis
3.6.1 Response
During the evaluation, the 900 Portable made TOC measurements once every 4 minutes.
The baseline concentration of TOC prior to injection is defined as the average
concentration over the 30 minute baseline measurement period before each injection.
Baseline measurement periods following injections began 20 minutes after the previous
injection. For the purposes of this study, the 900 Portable was considered able to detect
an anomalous change or "response" in TOC concentration following a contaminant
injection if the absolute change (ATOC) in TOC concentration was at least three times the
standard deviation of the baseline TOC concentration prior to the contaminant
introduction and three times the standard deviation of the post-injection TOC
concentration measurements. To simplify wording, in this report an anomalous change
will be referred to as a "response" to the contaminant injection. The response threshold
of three times the standard deviation was selected subjectively to indicate a change from
baseline as part of this evaluation. Depending on operational parameters of a water
system, a change in TOC that is at least three times the standard deviation of the baseline,
may or may not be of concern in terms of a contamination event.
In addition to the injection of the seven TICs, control injections of both chlorinated water
and chloraminated water were performed to determine if the act of injecting water into
the PPL caused a response for the 900 Portable. Water for control injections was
removed from the PPL and then injected back into the PPL within 4 hours. Five such
injections resulted in a standard deviation of 0.03 mg/L around zero TOC. Therefore, in
addition to the requirement for a response described in this section, a second requirement
for a response was that it must exceed the average and standard deviation of the blank
injections. Following this criteria (in addition to a change in TOC being at least three
times the baseline TOC), the threshold for detection was a change of 0.03 mg/L.
-------
Table 3-2. Contaminant List
Type
Toxic
Industrial
Chemicals
Biological
Contaminants
Toxins
Controls
Agent
AldicarbT
Carbofuran
Colchicine
Cyanide
Diesel fuel
Disulfoton
MevinphosT
Nicotine
Sodium Fluoroacetate
Bacillus thuringiensis
(surrogate for Bacillus
anthracis)
Bacillus globigii
(surrogate for Bacillus
anthracis)
Chlorella (surrogate for
Cryptosporidium)
Ovalbumin (surrogate for
botulinum toxin and
ricin)
Ricin
Water
PBS/nutrient broth
PBS/Bold 1NV medium
Buffered sodium azide
Analysis
Method
PPL
PPL, discrete
PPL
PPL
Discrete
Discrete
PPL
PPL
PPL
PPL
PPL
PPL
PPL
Discrete
PPL
PPL
PPL
Discrete
Concentrations
0.01,0.1, l(mg/L)
0.01,0.1, 1, 10(mg/L)
0.01,0.1, 1, 10(mg/L)
0.01,0.1, 1, 10(mg/L)
0.1, 1, 10(mg/L)
0.1, l(mg/L)
0.01,0.1, l(mg/L)
0.01,0.1, 1, 10(mg/L)
0.01,0.1, 1, 10(mg/L)
103,104, 105, 106, 107
(spores/L)
103,104, 105, 106, 107
(spores/L)
103, 104, 105 (cells/L)
0.01,0.1,1, 10(mg/L)
0.1, 1, 10(mg/L)
}
}
}
}
Medium
Water
Water
Water
Water
Water
Water
Water
Water
Water
PBS and
Nutrient Broth
PBS and
Nutrient Broth
PBS and Bold
1NV Medium
Water
Buffered
sodium azide
Water
Water
Water
Water
PBS-phosphate buffered saline
"fNo 10 mg/L injections due to the response at 1 mg/L and the prohibitive cost of 10 mg/L injections.
{ Concentrations (or volumes for water injections) equivalent to those present in contaminant injections.
The magnitude of a change in TOC concentration was calculated and expressed as
ATOC. The signal change of the 900 Portable as ATOC for TOC was calculated using
Equation 1:
ATOC = TOC - TOC
(1)
baseline
where TOC is the average post-injection TOC concentration measured by the 900
Portable (mg/L); and TOCbaseime is the average baseline TOC concentration as determined
by the 900 Portable (mg/L).
3.6.2 Accuracy
Results from the evaluation of the 900 Portable were compared to the results obtained
from analysis of reference grab samples collected during the same period. The results
for each sample are expressed in terms of the percent difference (%D) between the 900
Portable measurement and the reference measurements calculated from Equation 2:
-------
x10Q
l/2(OC + OCR)
(2)
where OCRis the concentration determined by the reference method (mg/L) and OC is the
average measurement from the 900 Portable when the reference sample was collected
(mg/L). Ideally, if the results from the 900 Portable and reference method measurement
are the same, %D would equal zero.
The combined experimental uncertainty (%U) of the %D was determined using the
method of propagation of errors and is defined by Equation 3:
%U = 100 X Vl6(OC + OCR)-4 X (OC|S£C + OC^S2CR) (3)
where SOCR and Soc are the standard deviations of OCR and OC, respectively.
10
-------
4.0 Quality Assurance/Quality Control
Quality assurance/quality control (QA/QC) procedures were performed in accordance
with the program QMP^ ^ and the test/QA plan*-1-* for this evaluation.
4.1 Reference Method
2(6)
EPA Method 415.3^; was used to analyze reference samples for TOC concentration. The
TM
reference instrument was a Teledyne-Tekmar (Mason, OH) Fusion TOC Analyzer
Reference samples were collected immediately after contaminant injections as well as
after the contaminant had become well-mixed in the PPL (steady-state). The analysis
method is summarized in Table 4-1.
Table 4-1. Summary of Total Organic Carbon Reference Method
Instrument
Teledyne-Tekmar
FusionTOC
Analyzer™
(Mason, OH)
Method
EPA 415. 36
(Standard
Method
53 IOC)
Measurement
Principle
UV/persulfate
oxidation
Detection
Limit
0.2 ng/L
Maximum
Holding Time
28 days with
acidification
to pH <2
4.2 Instrument Calibration
The contractor connected the 900 Portable to the PPL and the vendor representative
verified the instrument was operating properly. The vendor calibrated the 900 Portable
prior to shipment to the contractor and verified the calibration prior to testing using
vendor-provided calibration verification standards. A single point calibration for total
carbon and inorganic carbon was performed at 10 mg/L. Following the calibration, 5
mg/L verification standards were analyzed to verify the calibration.
The reference instrument was calibrated by the evaluation staff once prior to the start of
the evaluation and once per month throughout the approximately three month duration of
testing. Calibration check standards were analyzed with every batch of samples analyzed
using the TOC reference instrument to ensure that the reference instrument calibration
had not drifted. With the exception of one out of 56 days of analysis that occurred during
that three month time period, all calibration check standard analysis results were within
the required tolerance. Samples from that day were reanalyzed the next day, and the
calibration check standards for the reanalysis were within the acceptable tolerance.
11
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4.3 Audits
4.3.1 Performance Evaluation (PE) Audit
A performance evaluation (PE) audit was conducted to assess the accuracy of the TOC
reference method. A PE sample containing 5 mg/L organic carbon as potassium
hydrogen phthalate was obtained (Pharmaceutical Resource Associates [Environmental
Resource Associates], Arvada, CO) and analyzed. Accuracy of the TOC measurement
was expressed in terms of the percent error (%E), as calculated from the following
equation:
CR
(3)
where CRwas the standard or reference concentration of the PE sample and d is the
measurement obtained using the reference method. Ideally, if the reference value and the
measured value are the same, there would be a percent error of zero. Table 4-2 shows
that the results of the PE audit was below the maximum allowed %E for TOC.
Table 4-2. Performance Evaluation Audit Results
Reference Sample
TOC (Pharmaceutical Resource
Associates, Arvada, CO)
Expected Result
5. 00 mg/L
Reference
Method
Result
5. 30 mg/L
%E
6.0
Maximum
Allowed
20
TOC, total organic carbon
4.3.2 Technical Systems Audit (TSA)
The contractor QA manager conducted a technical systems audit (TSA) at the Columbus,
Ohio testing location to ensure that the evaluation was performed in accordance with the
test/QA plan(1) and the TTEP QMP(2). As part of the audit, the contractor QA manager
reviewed the reference sampling and analysis methods used, compared actual evaluation
procedures with those specified in the test/QA plan(1); and reviewed data acquisition and
handling procedures. No adverse findings were noted in this audit. The records
concerning the TSA are permanently stored with the contractor QA manager.
4.3.3 Amendments/Deviations
Investigators made one amendment to the test/QA plan for this evaluation. To
accommodate the latest needs of EPA's homeland security mission the amendment
changed the list of contaminants to be tested. The amendment removed cesium, as well
as the chemical warfare agents VX, soman, and sarin from the contaminant list and added
12
-------
ricin, disulfoton, mevinphos, and sodium fluoroacetate, to the list of injected
contaminants. The amendment stipulated that sodium fluoroacetate and mevinphos be
evaluated in the PPL and that ricin and disulfoton be evaluated as discrete samples, and
also changed the tests with diesel fuel from using the PPL to testing diesel as discrete
samples.
Throughout the course of testing, there were a few instances of slight deviation from the
test/QA plan.
• The PE sample for the reference method was analyzed after the first tests were
conducted rather than before testing began. The first attempt at the PE audit was
unsuccessful due to the use of PE audit samples that contained chemical
constituents that interfered with only the reference TOC instrument. However,
two TOC standards (one provided by the vendor) were measured accurately by
the reference method during preparation for the evaluation. Therefore, the
evaluation staff had a high degree of confidence in the accuracy of the reference
method/instrument. Instead of holding up the evaluation, testing proceeded
while interferent-free PE audit samples were being obtained.
• Investigators used an alternate test method for monochloramine. Rather than
using the difference between total and free chlorine (EPA method 330.5)*^, a test
for monochloramine (Hach® Method 10200),^ was used to determine the
monochloramine level in the chloraminated water used for testing.
• In addition to the levels specified in the test/QA plan (0.1, 1, and 10 mg/L) for
the TICs, injections at 0.01 mg/L were included in the test matrix. Some of the
technologies being assessed were more sensitive than investigators had
anticipated to the 0.1 mg/L injections. The injections at 0.01 mg/L were added
to better understand the performance of the analyzers at the low end of their
measurement range. In addition, because the 1 mg/L injections of aldicarb and
mevinphos were detected by all the technologies and the injection of 10 mg/L
would have been extremely expensive, the 10 mg/L tests were not performed.
• For the elevated TOC component of the testing, the TOC was elevated by
approximately 1 mg/L rather than 2 mg/L because of the change in background
TOC of the source water on the day of testing.
• Concentrations of the BCs were increased to include samples at 106 and 107
organisms/L to identify detectable levels.
• Percent difference was used to compare the reference method with the 900
Portable instead of percent error.
13
-------
4.3.4 Data Quality Audit
At least 10% of the data acquired during the evaluation were audited. The contractor QA
manager traced the data from the initial acquisition, through reduction and statistical
analysis, to final reporting, to ensure the integrity of the reported results. All calculations
performed on the data undergoing the audit were checked.
4.4 Quality Assurance/Quality Control (QA/QC) Reporting
Each assessment and audit was documented in accordance with the test/QA plan*-1-* and
the QMP.(2) Once an assessment report was prepared by the contractor QA manager, it
was routed to the EPA task order leader and the TTEP contract manager for review and
approval. The contractor QA manager then distributed the final assessment report to the
EPA task order project officer and the contractor QA manager.
14
-------
5.0 Evaluation Results
This section presents the evaluation results including the ability of the 900 Portable to
measure changes in TOC concentrations in response to the injection of TICs, toxins, and
BCs into drinking water. Also given are the accuracy of the 900 Portable TOC
measurements and the operational characteristics of the 900 Portable that were observed
during the evaluation.
5.1 Toxic Industrial Chemicals (TICs) in Drinking Water
5.1.1 900 Portable Response to TIC Injections
A total of seven toxic industrial chemicals (TICs) were individually injected into the PPL
at the concentration levels given in Table 3-2. As described in Section 3.3, contaminant
injections were performed in sets. Each set consisted of sequential injections of
increasing concentration to attain the target contaminant concentrations in the PPL.
Three sets of injections were performed for each contaminant. Section 3.6.1 thoroughly
describes the change in TOC concentration that was considered a " response" to a
contaminant injection. After each set of TIC injections, the PPL was flushed with
uncontaminated drinking water before the next set of injections was performed. The
results presented in this report reflect the scenarios specific to those defined by the
test/QA plan for this evaluation. As discussed in Section 3.3, it is possible that chemical
transformations took place during the solution preparation prior to contaminant injections
into the PPL.
Figure 5-1 shows an example of the 900 Portable response to one set of colchicine
injections into chlorinated water. Injections of colchicine are marked on Figure 5-1 with
vertical lines and labeled with the concentration level. The TOC concentration over the
time period prior to the first injection was used as the baseline TOC concentration for the
0.01 mg/L injection. In the set of injections shown, the 900 Portable did not have a
response to the 0.01 mg/L injection of colchicine but the 900 Portable did have a
response to the 0.1, 1, and 10 mg/L injections. During the 1 and 10 mg/L injections, the
900 Portable concentration did not increase until the third measurement after the
contaminant was injected into the PPL. This is because the 900 Portable only draws
sample for analysis once every four minutes. Therefore, the first reported concentration
(represented by the points on the line representing the TOC values in Figure 5-1)
following the injection represented water that had been drawn into the 900 Portable
before the contaminant injection and the second reported concentration represented water
that was drawn into the 900 Portable prior to the time when the water in the PPL was well
mixed. The data gap after the 1 mg/L injection was due to a reagent syringe fill cycle
that occurs periodically during 900 Portable operation.
15
-------
12
10
u
O
s.
8 4
01
Baseline
0.01 mg/L
,/> Injection
0.1 mg/L
^ Injection
J
lmg/L
.S Injection
10 mg/L
• s Injection
30 60 90 120 150
Time (minutes)
180
210
240
Figure 5-1. Change in 900 Portable total organic carbon (TOC) in response to
injections of colchicine.
Table 5-1 presents the contaminant injected, the concentration of the injected
contaminant, and the average and standard deviation of the measured change in TOC (as
measured by replicate measurements of the 900 Portable) for each TIC injection. Those
injections which were determined to produce a response (as defined previously) from the
900 Portable are highlighted in gray. The average change in TOC for reference samples
collected for the three replicates and analyzed by EPA Method 415.3 is also included.
Changes in TOC measured by the reference instrument were determined using the
standard deviation of the check standard analyses. Investigators used these samples
because the uncertainty of the reference method without the influence of the background
TOC (which varied daily) could be determined. The check standard was always the same
standard. Over the course of the evaluation, the standard deviation of reference analyses
of 2 mg/L check standards was 0.04 mg/L with an average of 2.13 mg/L for 28 samples.
Therefore, changes in TOC measured by the reference instrument greater than 0.12 mg/L
(three times the standard deviation) are highlighted in gray as changes in response to
contaminant injections.
The 900 Portable and the reference method measure the TOC concentration and not the
contaminant concentration (which would include all non-organic carbon substituents).
Therefore, the reference method and 900 Portable results would not be expected to be the
same as the injected nominal contaminant concentration, but the changes in TOC as
16
-------
Table 5-1. Change in 900 Portable Total Organic Carbon (TOC) from Injections of
Toxic Industrial Chemicals (TICs) into Chlorinated Water
Contaminant
Aldicarb
Carbofuran
Colchicine
Mevinphos
Nicotine
Potassium
Cyanide
Sodium
Fluoroacetate
Water
Controls
Injected
Contaminant
Cone. (mg/L)
0.01
0.1
1
0.01
0.1
1
10
0.01
0.1
1
10
0.01
0.1
1
0.01
0.1
1
10
0.01
0.1
1
10
0.01
0.1
1
10
None
Average
Reference
Method
ATOC
(mg/L)
-0.05
0.08
0.46
-0.03
0.04
0.52
4.05
0.02
0.07
0.66
8.02
-0.01
0.04
0.36
0.06
0.03
0.67
7.01
0.03
0.02
0.02
0.34
0.02
0.01
0.25
1.98
0.01
Injection 1
ATOC
(mg/L)
-0.13
-0.11
0.48
0.01
0.02
0.45
3.45
0.01
0.07
0.75
7.31
t
0.04
0.40
t
0.08
0.88
8.16
-0.01
0.01
0.03
0.08
0.00
0.03
0.25
1.81
-0.03
0.04
Std.
Dev.
(mg/L)
0.030
0.030
0.042
0.005
0.004
0.004
0.208
0.004
0.004
0.007
0.007
t
0.005
0.005
t
0.005
0.004
0.000
0.008
0.005
0.008
0.021
0.005
0.005
0.017
0.290
0.00
0.00
Injection 2
ATOC
(mg/L)
-0.02
0.05
0.52
0.01
0.10
0.68
7.36
0.00
0.11
0.71
7.37
0.00
0.04
0.39
0.01
0.09
0.87
7.68
-0.02
0.01
0.01
0.06
-0.01
0.02
0.27
2.07
0.00
0.00
Std.
Dev.
(mg/L)
0.021
0.008
0.011
0.051
0.015
0.021
0.580
0.011
0.005
0.008
0.008
0.005
0.005
0.005
0.005
0.005
0.005
0.035
0.012
0.005
0.005
0.019
0.011
0.005
0.005
0.040
0.00
0.00
Injection 3
ATOC
(mg/L)
0.02
0.08
0.48
-0.05
0.02
0.60
6.90
-0.02
0.07
0.75
7.45
0.00
0.04
0.39
0.06
0.08
0.92
8.02
-0.02
0.00
0.02
0.05
0.00
0.00
0.19
1.86
0.01
0.00*
Std.
Dev.
(mg/L)
0.020
0.020
0.005
0.021
0.011
0.109
0.238
0.013
0.004
0.000
0.045
0.007
0.004
0.005
0.008
0.005
0.000
0.049
0.005
0.005
0.000
0.005
0.005
0.005
0.029
0.444
0.00
0.02*
Responses (indicated by shading) must be at least three times the baseline standard deviation (in table) and the average
and standard deviation of the background injection result by exhibiting a response of at least 0.03 mg/L.
•f 900 Portable had to be restarted immediately following this injection.
{ Only two replicates of the 0.01 mg/L nicotine injections were performed.
* Average and standard deviation of water controls.
measured by the reference method should be similar to the changes in TOC measured by
the 900 Portable. In this case, the 900 Portable is being compared with a UV-persulfate
oxidation method and there may be inherent differences in how each method measure a
particular compound. Therefore, the differences in results between the 900 Portable and
the reference method may or may not indicate a deficiency in the 900 Portable.
In chlorinated water, with the exception of one injection of nicotine, the 900 Portable did
not respond to any contaminants at 0.01 mg/L. Carbofuran produced a response from the
17
-------
900 Portable for one of the three replicates at 0.1 mg/L. Aldicarb produced a response
from the 900 Portable for two out of three replicates at the 0.1 mg/L injection level.
Colchicine and nicotine produced a response from the 900 Portable for all replicates at
0.1 mg/L. Mevinphos was detected at both 0.1 and 1 mg/L. Potassium cyanide did not
produce a response from the 900 Portable for any 0.1 mg/L injection. With the exception
of two injections of potassium cyanide, all injections at 1 mg/L produced a response from
the 900 Portable. The 900 Portable measured responded to the injection of 10 mg/L of
each contaminant. For all the TIC injections into chlorinated water, the 900 Portable
responded at or below all contaminant concentrations for which the reference method
responded.
Table 5-2 presents the same information for injections made into the chloraminated water
Table 5-2. Change in 900 Portable Total Organic Carbon (TOC) from Injections of
Toxic Industrial Chemicals (TICs) into Chloraminated Water
Contaminant
Aldicarb
Carbofuran
Colchicine
Mevinphos
Nicotine
Potassium
Cyanide
Sodium
Fluoroacetate
Water
Controls
Injected
Cone.
(mg/L)
0.01
0.1
1
0.01
0.1
1
10
0.01
0.1
1
10
0.01
0.1
1
0.01
0.1
1
10
0.01
0.1
1
10
0.01
0.1
1
10
None
Average
Reference
Method
ATOC (mg/L)
-0.04
0.15
0.39
0.11
0.03
0.63
4.88
-0.02
0.08
0.69
6.41
0.01
0.05
0.36
0.03
0.08
0.68
6.86
0.02
0.01
0.03
0.37
0.01
0.03
0.30
2.17
0.01
Injection 1
ATOC
(mg/L)
-0.11
-0.05
0.51
-0.03
0.05
0.71
8.21
0.00
0.08
0.67
6.59
0.00
0.04
0.39
0.01
0.06
0.86
7.64
0.01
0.02
0.03
0.11
0.00
0.03
0.27
2.72
-0.03
0.04
Std.
Dev.
(mg/L)
0.031
0.031
0.006
0.014
0.009
0.108
0.185
0.004
0.004
0.012
0.123
0.000
0.005
0.011
0.000
0.005
0.012
0.064
0.006
0.005
0.005
0.026
0.008
0.000
0.000
0.007
0.00
0.00
Injection 2
ATOC
(mg/L)
-0.06
0.07
0.51
-0.23
-0.06
0.55
9.80
-0.06
0.07
0.66
6.66
0.01
0.03
0.36
0.01
0.11
0.95
8.26
0.00
0.02
0.02
0.10
-0.01
0.03
0.28
1.64
0.00
0.00
Std.
Dev.
(mg/L)
0.017
0.032
0.032
0.051
0.051
0.046
1.031
0.052
0.004
0.022
0.087
0.004
0.004
0.033
0.004
0.005
0.005
0.055
0.005
0.006
0.006
0.015
0.005
0.004
0.004
0.530
0.00
0.00
Injection 3
ATOC
(mg/L)
0.01
0.06
0.50
-0.04
0.06
0.70
8.78
0.00
0.07
0.72
7.11
0.00
0.04
0.41
0.01
0.10
0.85
8.22
0.01
0.01
0.02
0.07
0.00
0.02
0.25
2.12
0.01
0.00T
Std.
Dev.
(mg/L)
0.005
0.000
0.000
0.027
0.031
0.031
0.348
0.004
0.007
0.007
0.021
0.004
0.000
0.004
0.005
0.004
0.004
0.052
0.006
0.005
0.005
0.035
0.005
0.004
0.041
0.035
0.00
0.02T
Responses (indicated by shading) must be at least three times the baseline standard deviation (in table) and the average
and standard deviation of the background injection result by exhibiting a response of at least 0.03 mg/L.
t Average and standard deviation of water controls.
18
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matrix. In general, the results are similar for chlorinated and chloraminated water. The
differences were as follows: the 900 Portable did not respond to any injections at 0.01
mg/L with chloraminated water, gave two responses with chloraminated water (instead of
one with chlorinated water) to injections of 0.1 mg/L carbofuran, and gave two responses
(instead of one with chlorinated water) with chloraminated water to 0.1 mg/L sodium
fluoroacetate. With the exception of potassium cyanide, all of the TICs caused
approximately a linear increase in TOC with increasing concentration. The 900 Portable
response to potassium cyanide was never larger than 0.11 mg/L, even for injections at 10
mg/L of potassium cyanide. The 900 Portable responded at or below the lowest
concentration producing a response with the reference method for all TIC injections
except for two injections of aldicarb at 0.1 mg/L.
5.1.2 900 Portable Accuracy during Toxic Industrial Chemical (TIC) Testing
Table 5-3 and Table 5-4 compare the steady-state TOC measurements obtained for PPL
reference samples by the 900 Portable to the measurements obtained by the reference
method. In addition to the steady-state contaminant concentrations in the second column,
the actual TOC concentrations and standard deviations measured by the reference method
and the 900 Portable are shown in the middle columns. These measurements include the
background TOC concentration of the drinking water used for the testing in addition to
any contribution of TOC from the injected contaminant. The last column includes the
percent difference (%D) between the average 900 Portable TOC measurement and the
average reference TOC measurement. This %D can be used to assess the accuracy of the
900 Portable measurements. As mentioned before, TOC instruments and methods can
provide different responses to contaminants. In most cases, the average and standard
deviation reported are based on three replicate measurements, however, in some cases,
the results are based on four replicates. The propagated experimental uncertainty of the
%D is shown in the same column as %D in Table 5-3 and 5-4.
The average %D between the 900 Portable and the reference method was typically less
than 20% with the only exceptions being data collected for carbofuran (28-46%),
mevinphos (21-23%), and sodium fluoroacetate (20%). The data for carbofuran show
that there is a larger %D for samples collected after the 10 mg/L injections. The absolute
value of the %Ds between the 900 Portable and the reference method for all the
comparisons across the evaluation was 14% plus or minus (±) a standard deviation (SD)
of 7%. For TICs in chlorinated and chloraminated water, the absolute value of the %Ds
averaged 15% ± 5% and 14% ± 8%, respectively. In general, the standard deviations
generated by the reference instrument were similar to the 900 Portable. The propagated
experimental uncertainty was typically small with respect to %D. There were only a few
instances when the %D did not result in a statistically significant difference between the
900 Portable and the reference method.
19
-------
Table 5-3. 900 Portable Accuracy for Toxic Industrial Chemicals (TICs) in
Chlorinated Water
Contaminant
Aldicarb
Carbofuran
Colchicine
Mevinphos
Nicotine
Potassium
Cyanide
Sodium
Fluoroacetate
Injected
Contaminant
Concentration
(mg/L)
Pre-Injection
0.01
0.1
1
Pre-Injection
0.01
0.1
1
10
Pre-Injection
0.01
0.1
1
10
Pre-Injection
0.01
0.1
1
Pre-Injection
0.01
0.1
1
10
Pre-Injection
0.01
0.1
1
10
Pre-Injection
0.01
0.1
1
10
Reference TOC
Average
(mg/L)
2.52
2.47
2.55
3.01
2.45
2.51
2.55
3.07
7.12
2.41
2.43
2.50
3.16
11.19
1.38
1.37
1.42
1.77
2.54
2.55
2.63
3.29
10.05
2.37
2.41
2.43
2.45
2.79
1.60
1.55
1.55
1.81
3.66
Std.f
Dev.
(mg/L)
0.14
0.15
0.20
0.24
0.07
0.16
0.15
0.24
1.54
0.05
0.05
0.04
0.06
0.16
0.00
0.01
0.03
0.04
0.10
0.03
0.03
0.06
2.06
0.06
0.06
0.06
0.08
0.06
0.16
0.12
0.10
0.08
0.21
900 Portable TOC
Average
(mg/L)
2.95
2.91
2.91
3.40
2.96
2.95
3.00
3.57
9.47
2.77
2.76
2.84
3.58
10.96
1.71
1.72
1.76
2.15
2.89
2.90
3.01
3.90
11.53
2.72
2.70
2.71
2.72
2.79
1.95
1.86
1.88
2.12
3.96
Std.f
Dev.
(mg/L)
0.40
0.32
0.22
0.21
0.23
0.20
0.20
0.29
2.42
0.03
0.05
0.07
0.05
0.05
0.00
0.01
0.01
0.01
0.06
0.07
0.06
0.08
0.88
0.07
0.07
0.08
0.07
0.09
0.16
0.13
0.11
0.08
0.15
Percent
Difference
(%D)
16 ±14
16 ±12
13 ±10
12 ±9.3
19 ±8.0
16 ±8.6
16 ±8.3
15 ±10
28 ±30
14±2.1
13 ±2.6
13 ±2.8
13 ±2.2
-2.1 ±1.5
21 ±0.0
23 ±0.8
21 ±1.8
19±1.9
13 ±4.0
13 ±2.6
14 ±2.2
17 ±2.5
14 ±19
14 ±3.4
11±3.4
11±3.7
10 ±3. 9
0.0 ±3.9
20 ±12
18 ±9.4
19 ±7.8
16 ±5. 3
7.9 ±6.5
f Standard deviation is of the replicates on which the average TOC concentration is based.
In addition to the accuracy data presented in Tables 5-3 and 5-4, the standard deviation
data presented represents not only the precision of the baseline measurements, but the
precision of the resulting TOC concentration due to the injections themselves. This
measure of precision could be used to calculate the amount of change that would be
required to detect a contamination event. For example, if the TOC measurements for a
set of replicate injections are precise (e.g., 1 mg/L mevinphos) and therefore, has a low
standard deviation, a small change would be detectable. Conversely, if the TOC
measurements for a set of replicates (e.g. 10 mg/L carbofuran) are imprecise and,
therefore, have a larger standard deviation, a relatively larger change in TOC would be
20
-------
Table 5-4. 900 Portable Accuracy for Toxic Industrial Chemicals (TICs) in
Chloraminated Water
Contaminant
Aldicarb
Carbofuran
Colchicine
Mevinphos
Nicotine
Potassium
Cyanide
Sodium
Fluoroacetate
Injected
Contaminant
Concentration
(mg/L)
Pre-Injection
0.01
0.1
1
Pre-Injection
0.01
0.1
1
10
Pre-Injection
0.01
0.1
1
10
Pre-Injection
0.01
0.1
1
Pre-Injection
0.01
0.1
1
10
Pre-Injection
0.01
0.1
1
10
Pre-Injection
0.01
0.1
1
10
Reference TOC
Average
(mg/L)
2.01
1.92
2.07
2.46
1.95
2.06
2.09
2.72
7.60
1.80
1.79
1.88
2.59
9.04
.43
.44
.49
.85
.92
.95
2.03
2.71
9.56
.91
.93
.94
.97
2.34
.56
.50
.53
.83
3.86
Std.f
Dev.
(mg/L)
0.36
0.32
0.45
0.40
0.18
0.30
0.24
0.30
0.16
0.09
0.05
0.05
0.11
0.09
0.02
0.03
0.02
0.03
0.12
0.11
0.09
0.08
0.35
0.05
0.05
0.03
0.04
0.03
0.10
0.05
0.05
0.14
0.45
900 Portable TOC
Average
(mg/L)
2.40
2.27
2.30
2.81
2.60
2.50
2.52
3.17
12.10
1.94
1.91
1.98
2.67
9.56
1.77
1.77
1.81
2.19
2.08
2.09
2.18
3.06
11.10
2.14
2.15
2.17
2.19
2.28
1.89
1.81
1.84
2.10
4.19
Std.f
Dev.
(mg/L)
0.52
0.56
0.50
0.51
0.60
0.50
0.45
0.38
1.16
0.14
0.09
0.09
0.04
0.28
0.02
0.01
0.02
0.04
0.12
0.12
0.10
0.10
0.29
0.03
0.03
0.03
0.04
0.06
0.10
0.02
0.02
0.02
0.58
Percent
Difference
(%)
18 ±26
17 ±28
10 ±29
13 ±23
29 ±24
19 ±23
19 ±20
15 ±15
46 ± 9.2
7.5 ±8.6
6.5 ±5.4
5.2 ±5.2
3.0 ±4.4
5.6 ±3.1
21 ±1.6
21 ±1.8
19 ±1.5
17 ±2.3
8.0 ±8.1
6.9 ±7.8
7.1 ±6.2
12 ±4.2
15±4.1
11 ±2.7
11 ±2.7
11 ±1.9
11 ±2.6
-2.6 ±2.9
19 ±7.4
19 ±2.9
18 ±2.9
14 ±6.7
8.2 ±18
T Standard deviation is of the replicates on which the average TOC concentration is based.
necessary to attain a detectable concentration. These data are also useful for evaluating
the precision of the 900 Portable versus the reference method. In many cases, the
precision data are rather similar. In this instance, the precision is not only dependent on
the instrument, but also on experimental factors having to do with the PPL operation.
However, similar variables may exist in the context in an operational setting.
As is evident from the preinjection TOC levels, the water in the laboratory did show
some variation over the course of the evaluation. The average pre-injection baseline
TOC in the water ranged from 1.38 mg/L to 2.54 mg/L during the TIC evaluation period.
21
-------
However, during the course of each set of replicate contaminant injections, the
background TOC was steady because the same water was used for each contaminant
injection.
5.2 Biological Contaminants (BCs) in Drinking Water
5.2.1 900 Portable Response to Biological Contaminant (BC) Injections
Three types of BCs and one toxin surrogate were injected into the PPL. These injections
were performed in the same manner as the TIC injections with a concentrated solution
injected into the PPL over approximately 15-20 seconds. The same injection and flush
procedures were used and response determination (as defined in Section 3.6.1) was
performed in the same way. Figure 5-2 shows that the 900 Portable did not respond to
any of the injected concentrations (103, 104, and 105 organisms/L) of Bacillus globigii.
Initially, concentrations of 103, 104, and 105 organisms/L were injected into the PPL for
each organism. After the results of the initial injections showed no response, the
concentrations were increased to include a maximum concentration of 107 organisms/L
for Bacillus globigii and Bacillus thuringiensis. This increased concentration of Bacillus
thuringiensis was a mixture of spores and vegetative cells while the other concentrations
were spores only. Limitations on the amount of stock solution available prevented
increasing the concentrations of Chlorella in a similar manner.
12
10
u
O
.Q
ra
t
O
Q_
8 4
01
103 organism/
Baseline Injection ->£
*cV£fr1fc
Injection
^
105 organism/L
^/ Injection
30 60 90 120 150 180
Time (minutes)
210
240
270
300
Figure 5-2. Change in 900 Portable Total Organic Carbon (TOC) response to
injections of Bacillus globigii.
22
-------
Table 5-5 presents the contaminant injected, the concentration of the injected
contaminant, and the average and standard deviation of the measured change in TOC (as
measured by replicate measurements of the 900 Portable) for each BC injection into
chlorinated water. Those injections which the 900 Portable responded are highlighted in
gray. The 900 Portable "response" is defined as described in Section 3.6.1.
Table 5-5. Change in 900 Portable Total Organic Carbon (TOC) from Injections of
Biological Contaminants (BCs) into Chlorinated Water
Contaminant
Bacillus
globigii
Bacillus
thuringiensis
Chlorella
Ovalbumin
Water
controls
PBS/nutrient
broth
PBS/Bold
1NV medium
Injected
Contaminant
Cone.
(organism/L
or mg/L)
105
106
10'
105
106
107
103
104
10s
0.01
0.1
1
10
None
Equivalent to
107 Bacillus
Equivalent to
107 Chlorella
Average
Reference
Method
ATOC
(mg/L)
-0.09
0.01
-0.03
-0.03
-0.02
-0.02
-0.04
-0.04
-0.04
0.01
0.02
0.09
1.10
0.01
-0.02
-0.01
Injection 1
ATOC
(mg/L)
0.00
-0.01
-0.01
-0.02
0.01
0.07
-0.01
0.00
0.00
0.02
0.04
0.31
4.75
-0.03
0.04
-0.01
-0.00
0.00
-0.01
Std.
Dev.
(mg/L)
0.000
0.007
0.007
0.012
0.000
0.004
0.006
0.004
0.005
0.000
0.021
0.041
0.081
0.00
0.00
0.00
0.00
0.01
0.01
Injection 2
ATOC
(mg/L)
0.00
-0.01
0.01
0.00
0.00
0.05
0.01
-0.01
0.00
-0.01
0.03
0.32
4.48
0.00
0.00
0.02
0.01
0.00
0.02
Std.
Dev.
(mg/L)
0.004
0.005
0.005
0.000
0.000
0.005
0.000
0.000
0.000
0.006
0.006
0.016
0.047
0.00
0.00
0.01
0.02
0.00
0.00
Injection 3
ATOC
(mg/L)
0.00
0.00
0.00
0.00
0.00
0.03
0.01
0.02
0.00
0.03
0.03
0.35
4.60
0.01
0.00T
-0.01
-0.01
0.01
-0.01
Std.
Dev.
(mg/L)
0.000
0.005
0.005
0.013
0.004
0.013
0.005
0.010
0.010
0.007
0.008
0.013
0.125
0.00
0.02T
0.00
0.00
0.00
0.00
Responses (indicated by shading) must be at least three times the baseline standard deviation (in table) and the average
and standard deviation of the background injection result by exhibiting a response of at least 0.03 mg/L.
Average and standard deviation of water controls.
None of the injections of Bacillus globigii or Chlorella resulted in a response from the
900 Portable at the concentrations injected. All three injections of Bacillus thuringiensis
at 107 organisms/L including spores and vegetative cells resulted in a response from the
900 Portable. The reference method responded to none of the BCs. Ovalbumin, a protein
surrogate for biological toxins such as ricin or botulinum, produced a response from the
900 Portable for all three 0.1 mg/L, 1 mg/L, and 10 mg/L injections. The reference
method measured a response in TOC only for the 10 mg/L injections of Ovalbumin.
Table 5-6 presents the response to injections of the BCs and ovalbumin into
chloraminated water. Initial injections of Bacillus globigii were performed at 103, 104,
and 105 organisms/L. One injection of 107 organisms/L was included with the final
23
-------
Table 5-6. Change in 900 Portable Total Organic Carbon (TOC) from Injection of
Biological Contaminants (BCs) into Chloraminated Water
Contaminant
Bacillus
globigii
Bacillus
thuringiensis
Chlorella
Ovalbumin
Water
controls
PBS/nutrient
broth
PBS/Bold
1NV medium
Injected
Cone.
(organism/L
or mg/L)
103
104
10s
10'
103
104
105
106
10'
103
104
10s
0.01
0.1
1
10
None
Equivalent to
107 Bacillus
Equivalent to
107 Chlorella
Average
Reference
Method
ATOC
(mg/L)
-0.01
-0.03
-0.01
-0.05
-0.03
-0.03
-0.02
-0.04
-0.01
-0.05
-0.04
-0.02
-0.01
0.04
0.29
1.34
0.01
-0.02
-0.01
Injection 1
ATOC
(mg/L)
0.01
0.00
0.00
t
-0.01
0.00
0.03
t
t
-0.01
0.01
0.00
-0.02
0.01
0.32
5.41
-0.03
0.04
-0.01
-0.00
0.00
-0.01
Std.
Dev.
(mg/L)
0.005
0.000
0.003
t
0.007
0.004
0.004
t
t
0.006
0.000
0.000
0.008
0.005
0.036
0.045
0.00
0.00
0.00
0.00
0.01
0.01
Injection 2
ATOC
(mg/L)
-0.02
0.00
0.00
t
-0.02
-0.01
0.03
t
t
0.00
0.00
0.00
0.02
0.02
0.45
5.24
0.00
0.00
0.02
0.01
0.00
0.02
Std.
Dev.
(mg/L)
0.005
0.005
0.005
t
0.010
0.005
0.005
t
t
0.005
0.005
0.000
0.005
0.005
0.057
0.057
0.00
0.00
0.01
0.02
0.00
0.00
Injection 3
ATOC
(mg/L)
-0.02
0.00
0.00
0.01
t
t
-0.01
0.00
0.05
-0.07
0.00
0.01
0.00
0.03
0.47
5.02
0.01
0.00*
-0.01
-0.01
0.01
-0.01
Std.
Dev.
(mg/L)
0.005
0.005
0.004
0.004
t
t
0.004
0.000
0.000
0.044
0.000
0.005
0.005
0.000
0.039
0.054
0.00
0.02*
0.00
0.00
0.00
0.00
Responses (indicated by shading) must be at least three times the baseline standard deviation (in table) and the average
and standard deviation of the background injection result by exhibiting a response of at least 0.03 mg/L.
f Fewer than three replicates performed at this concentration.
* Average and standard deviation of water controls.
replicate set of injections to confirm the results determined during the chlorinated water
injections. The final set of injections of Bacillus thuringiensis was also performed at 105,
106, and 107 organisms/L. Injections which produced a response in the 900 Portable TOC
concentration and the reference method are highlighted in gray.
In chloraminated water, none of the Bacillus globigii or Chlorella injections resulted in a
response from the 900 Portable. The only BC injection that resulted in a response from
the 900 Portable was of Bacillus thuringiensis at 107 organisms/L including spores and
vegetative cells. The reference method did not respond to any of the organism injections.
The 900 Portable and the reference method both measured a response to ovalbumin for
all of the 1 and 10 mg/L injections.
In addition to the injections of BCs, control injections of freshly prepared growth media
handled in the same manner as the stock solutions of the BCs, but without organisms
added, were injected into the PPL. Triplicate sets of injections of the washed growth
24
-------
media for both the Bacillus organisms and Chlorella were made into chlorinated and
chloraminated water. None of the 12 injections produced a change in TOC that was
detectable by the 900 Portable or the reference method.
5.2.2 900 Portable Accuracy during Biological Contaminant (BC) Testing
Table 5-7 and Table 5-8 summarize the comparisons of the steady-state TOC
measurements from the 900 Portable to the results obtained from the reference method
through analysis of reference samples from the PPL for chlorinated and chloraminated
water, respectively. In addition to the steady-state contaminant concentrations in the
second column, the reference TOC concentrations and standard deviations measured by
the 900 Portable and the reference method are shown in the middle columns. These
measurements include the background TOC concentration of the drinking water used for
the testing in addition to any contribution of TOC from the injected contaminant. The
last column includes the %D between the average 900 Portable measurement and the
average reference measurement. This %D can be used to assess the accuracy of the 900
Portable measurements. In most cases, the average and standard deviation reported are
based on three replicate measurements, but in some instances there were four replicates.
The average % D between the 900 Portable and the reference method was typically less
than 25% with the only exceptions being 107 organisms/L of Bacillus thuringiensis in
chloraminated water (27%), and 10 mg/L of ovalbumin (73-75%). In general,
Table 5-7. 900 Portable Accuracy for Biological Contaminants (BCs) in
Chlorinated Water
Contaminant
Bacillus
globigii
Bacillus
thuringiensis
Chlorella
Ovalbumin
Contaminant
Concentration
(mg/L or
organisms/L)
Pre-Injection
10'
106
107
Pre-Injection
10'
106
107
Pre-Injection
103
104
10'
Pre-Injection
0.01
0.1
1
10
Reference TOC
Average
(mg/L)
.61
.52
.54
.51
.54
.50
.48
.49
.66
.62
.58
.54
2.38
2.39
2.41
2.50
3.59
Std.f
Dev.
(mg/L)
0.09
0.10
0.06
0.06
0.08
0.09
0.11
0.07
0.02
0.02
0.01
0.03
0.02
0.01
0.02
0.04
0.31
900 Portable TOC
Average
(mg/L)
1.86
1.86
1.86
1.85
1.86
1.86
1.86
1.90
1.92
1.93
1.93
1.93
2.74
2.76
2.79
3.12
7.73
Std.f
Dev.
(mg/L)
0.10
0.10
0.09
0.09
0.08
0.06
0.06
0.09
0.02
0.02
0.00
0.00
0.02
0.02
0.02
0.04
0.14
Percent
Difference
(%)
14 ±7.2
20 ±7.5
19 ±5.8
20 ±5.8
19 ±6.0
21 ±5.7
23 ±6.6
24 ±5.9
14 ± 1.5
18 ±1.5
20 ±0.5
22 ±1.5
14 ±1.0
14 ±0.8
15 ±1.0
22 ±1.8
73 ±3.8
f Standard deviation is of the replicates on which the average TOC concentration is based.
25
-------
Table 5-8. 900 Portable Accuracy for Biological Contaminants (BCs) in
Chloraminated Water
Contaminant
Bacillus
globigii
Bacillus
thuringiensis
Chlorella
Ovalbumin
Contaminant
Concentration
(mg/L or
organisms/L)
Pre-Injection
103
104
10*
10'
Pre-Injection
103
104
10*
106
10'
Pre-Injection
103
104
10*
Pre-Injection
0.01
0.1
1
10
Reference TOC
Average
(mg/L)
.76
.75
.72
.71
.62
.63
.68
.65
.56
.38
.38
.46
.41
.37
.36
.80
.78
.83
2.12
3.46
Std.f
Dev.
(mg/L)
0.02
0.01
0.03
0.04
}
0.14
0.01
0.01
0.12
}
}
0.08
0.07
0.07
0.08
0.04
0.03
0.04
0.28
0.20
900 Portable TOC
Average
(mg/L)
1.94
1.93
1.93
1.93
1.93
1.84
1.87
1.87
1.85
1.76
1.81
1.74
1.71
1.72
1.72
1.95
1.95
1.97
2.38
7.60
Std.f
Dev.
(mg/L)
0.02
0.01
0.01
0.01
}
0.07
0.01
0.01
0.07
}
}
0.03
0.07
0.07
0.06
0.06
0.06
0.07
0.15
0.08
Percent
Difference
(%)
9.7 ±1.5
9.8 ±0.7
12 ±1.6
12±2.1
18
12 ±8.5
11±0.8
12 ±0.8
17 ±7.5
24
27
18 ±4.9
19 ±5.7
23 ±5.7
23 ±5.7
8.0 ±3.7
9.1 ±3.4
7.4 ±4.1
12 ±13
75 ±2.4
'[Standard deviation is of the replicates on which the average TOC concentration is based.
Only one replicate conducted at these concentrations.
the standard deviations generated by the reference instrument were similar to the 900
Portable. For the biological contaminants (excluding the lOmg/L ovalbumin
measurements), the average of the absolute values of the %D was 19% ± SD 3% and
15% ± SD 6% for chlorinated and chloraminated water, respectively. For each individual
comparison, the experimental error was propagated using the uncertainty of both
measurements and is reported. In most cases the differences between the 900 Portable
results and the reference method results are larger than the experimental uncertainty. In
general, the 900 Portable measured higher TOC than the reference method for BC
samples. Injections of 10 mg/L of ovalbumin resulted in 73 to 75 percent difference with
the 900 Portable measuring higher TOC concentrations than the reference method. There
is no definite explanation for this, although the data suggests that the 900 Portable
responds more linearly to ovalbumin that does the reference method.
As is evident from the pre-injection TOC levels, the water in the laboratory did show
some variation over the course of the testing. The average pre-injection baseline TOC in
the water ranged from 1.46 mg/L to 2.38 mg/L during the BC evaluation period.
However, during the course of each set of replicate contaminant injections, the
background TOC was steady because the same water was used for each contaminant
injection.
26
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5.3 Discrete Sample Analyses
5.3.1 900 Portable Response for Discrete Sample Analyses
Three contaminants were analyzed as discrete samples to minimize the volume used for
injection of some of the contaminants. Carbofuran was analyzed in discrete samples as
well as in the PPL. For the PPL tests, water was continuously flowing through the 900
Portable inlet whereas for the discrete tests, the 900 Portable was operated in grab sample
analysis mode with samples drawn from a static 40 mL vial containing the solution to be
tested. In grab sample mode, the 900 Portable drew four samples from the vial and
reported a concentration as the average of the final three measurements. The reported
concentration is the average of the measurements collected from one vial. The discrete
samples were analyzed in a similar manner to the tests in the PPL increasing from
drinking water to the highest concentration analyzed. Three vials of each concentration
were analyzed in both chlorinated and chloraminated water for each contaminant.
Table 5-9 and Table 5-10 give the contaminant tested, the concentration of the
contaminant, the measured change in TOC, and the standard deviation for each
contaminant concentration in chlorinated and chloraminated water, respectively. The 900
Portable responded to the concentrations highlighted in gray. Results of the ricin and
sodium azide phosphate buffer samples are included in both tables.
Table 5-9. Change in 900 Portable Total Organic Carbon (TOC) for Discrete
Sample Analyses in Chlorinated Water
Contaminant
Carbofuran
Diesel fuel
Disulfoton
Ricin
Sodium
azide/phosphate
buffer (ricin
blank)
Solution
Contaminant
Cone. (mg/L)
0.1
1
0.1
1
10
0.1
1
0.1
1
10
0.1
1
10
Average
Reference
Method
ATOC
(mg/L)
t
t
0.12
0.00
-0.02
-0.01
-0.23
}
Viall
ATOC
(mg/L)
0.06
0.27
0.19
0.11
0.43
0.02
0.19
0.04
0.30
4.47
-0.07
-0.05
-0.11
Std.
Dev.
(mg/L)
0.000
0.000
0.012
0.000
0.010
0.006
0.006
0.000
0.010
0.050
0.006
0.006
0.006
Vial 2
ATOC
(mg/L)
0.05
0.29
0.13
0.11
0.54
0.00
0.16
-0.06
0.28
4.56
Std.
Dev.
(mg/L)
0.000
0.000
0.015
0.015
0.015
0.006
0.000
0.042
0.042
0.042
Vial 3
ATOC
(mg/L)
0.05
0.30
0.11
0.10
0.53
0.02
0.17
0.11
0.40
4.65
Std.
Dev.
(mg/L)
0.000
0.006
0.015
0.015
0.015
0.006
0.006
0.000
0.000
0.012
*
Responses (indicated by shading) must be at least three times standard deviation.
Reference samples not analyzed for discrete analyses of carbofuran in chlorinated water.
Reference instrument could not be placed within the biosafety hood so ricin and corresponding azide blanks reference
analyses were not performed.
One set of blank replicate samples were analyzed.
27
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Table 5-10. Change in 900 Portable Total Organic Carbon (TOC) for Discrete
Sample Analyses in Chloraminated Water
Contaminant
Carbofuran
Diesel fuel
Disulfoton
Ricin
Sodium
azide/phosphate
buffer
Solution
Contaminant
Cone. (mg/L)
0.1
1
0.1
1
10
0.1
1
0.1
1
10
0.1
1
10
Average
Reference
Method
ATOC
(mg/L)
0.07
0.30
0.00
0.03
0.05
-0.01
0.29
}
Viall
ATOC
(mg/L)
0.11
0.38
-0.01
0.27
1.13
0.02
0.30
0.01
0.43
4.81
0.00
0.00
-0.01
Std.f
Dev.
(mg/L)
0.006
0.000
0.006
0.006
0.021
0.006
0.006
0.000
0.006
0.021
0.006
0.006
0.006
Vial 2
ATOC
(mg/L)
0.05
0.77
-0.05
0.15
0.37
0.04
0.32
0.00
0.41
4.77
Std.f
Dev.
(mg/L)
0.006
0.006
0.020
0.020
0.020
0.000
0.000
0.012
0.012
0.021
Vial 3
ATOC
(mg/L)
0.04
0.52
0.01
0.22
0.31
0.05
0.32
0.03
0.44
4.77
Std.f
Dev.
(mg/L)
0.006
0.006
0.015
0.015
0.015
0.006
0.006
0.010
0.010
0.010
*
Responses (indicated by shading) must be at least three times standard deviation.
Reference instrument could not be placed within the biosafety hood so ricin and corresponding azide blanks reference
analyses were not performed.
One set of blank replicate samples were analyzed.
The ricin was stored in the sodium azide phosphate buffer so, along with each
measurement of ricin, the sodium azide phosphate buffer was analyzed at the
concentration at which it was present in the ricin solutions. The diesel fuel, disulfoton,
and carbofuran were insoluble or only partially soluble in water making interpretation of
the 900 Portable and reference method results for these discrete samples difficult.
5.3.1.1 Carbofuran
Discrete analyses of carbofuran at 0.1 and 1 mg/L were conducted. No analysis of
discrete 10 mg/L carbofuran samples was conducted due to the limited solubility of
carbofuran. During the discrete analyses, the 900 Portable responded to both the 0.1 and
1 mg/L concentration levels in both chlorinated and chloraminated water. The 900
Portable responded to all of the discrete samples of carbofuran except for one of the 0.1
mg/L tests in chloraminated water. The 0.1 mg/L injections of carbofuran into the PPL
produced responses for two of three injections in chlorinated water and one of three
injections in chloraminated water (see Table 5-2, 5-3, respectively). For the discrete
analyses, the reference method responded to only the 1 mg/L injections of carbofuran into
chloraminated water. The discrete samples produced TOC readings that were about half
the PPL analyses readings. The reason for this difference in results between the
experimental setups was not obvious.
28
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5.3.1.2 Diesel fuel
Discrete analysis of diesel fuel samples was conducted at 0.1, 1, and 10 mg/L. The
solubility of diesel was such that diesel was insoluble in water at any of the
concentrations evaluated. For each sample, two phases were visible with diesel on top of
water. Prior to each analysis, the samples were mixed, but over the course of the analysis
period the samples began to separate into a distinct diesel (organic) phase and an aqueous
phase. The 900 Portable responded to all diesel samples in chlorinated water and for 1
and 10 mg/L of diesel in chloraminated water. With similar inconsistency, only the
lowest concentration diesel was detected by the reference method. These inconsistent
results can be explained by the lack of solubility of diesel fuel. Without a homogeneous
solution, results from any chemical measurement, including TOC, is problematic.
5.3.1.3 Disulfoton.
Discrete analysis of disulfoton samples was conducted at 0.1 and 1 mg/L. No analysis of
discrete 10 mg/L disulfoton samples was conducted due to the limited solubility of
disulfoton. The 900 Portable responded to 1 mg/L of disulfoton in both chlorinated and
chloraminated water and for one test of 0.1 mg/L in chloraminated water. The reference
method did not respond to the 1 mg/L of disulfoton in chlorinated water, but respond to 1
mg/L in chloraminated water. There was not a clear reason for the response differences
between the two water matrices.
5.3.1.4 Ricin.
Ricin tests were carried out inside a hood in a biological safety level 2 (BSL-2)
laboratory. Discrete analysis of ricin samples was conducted at 0.1, 1, and 10 mg/L. The
900 Portable responded to all of the 1 and 10 mg/L samples. As mentioned above, the
sodium azide phosphate buffer solution was analyzed at the same concentrations at which
it was present in the ricin solutions to determine whether the 900 Portable responded due
to the sodium azide phosphate buffer. The 900 Portable responded to 0.1 mg/L for one
test in chlorinated water but to none of the tests in chloraminated water. The phosphate
buffered sodium azide solution did not cause any change in TOC in either water matrix,
therefore, the change in TOC concentration due to ricin was considered to be anomalous.
Analysis of ricin by the reference method would have required relocation of the reference
instrument into a BSL-2 hood, which was not logistically possible.
5.3.2 900 Portable Accuracy during Discrete Sample Analyses
Table 5-11 and Table 5-12 summarize the comparison of the TOC measurements from
the 900 Portable to the results obtained from the reference method through analysis of
samples prepared in the same manner as the test samples analyzed by the 900 Portable in
chlorinated and chloraminated water, respectively.
The average %D of the 900 Portable compared to the reference method was typically less
than 25% for discrete sample analyses. The only exceptions were diesel fuel (38-41%)
and carbofuran (17-27%). Overall, the absolute value of the %D for the chlorinated
water was 21% ± SD 8%, for chloraminated water 23% ± SD 7%, for an overall average
absolute %D of 22% ± SD 8%.
29
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Table 5-11. 900 Portable Accuracy for Discrete Sample Analyses in Chlorinated
Water
Contaminant
Carbofuran
Diesel fuel
Disulfoton
Contaminant
Concentration
(mg/L)
Water
0.1
1
Water
0.1
1
10
Water
0.1
1
Reference TOC
Average (mg/L)
t
t
t
.64
.76
.64
.62
.33
.36
.56
900 Portable TOC
Average
(mg/L)
1.65
1.70
1.93
1.87
2.01
1.98
2.37
1.68
1.70
1.86
Std. Dev.
(mg/L)
0.02
0.01
0.01
0.03
0.01
0.03
0.09
0.01
0.01
0.01
Percent
Difference
(%D)
t
t
t
13 ± .9
13 ± .1
19 ± .8
38 ±3.8
23 ± .3
22 ± .3
18 ± .2
^Reference samples not analyzed for this concentration.
Table 5-12. 900 Portable Accuracy for Discrete Sample Analyses in Chloraminated
Water
Contaminant
Carbofuran
Diesel fuel
Disulfoton
Contaminant
Concentration
(mg/L)
Water
0.1
1
Water
0.1
1
10
Water
0.1
1
Reference TOC
Average (mg/L)
1.41
1.48
1.71
1.89
1.88
1.92
1.94
1.57
1.62
1.85
900 Portable TOC
Average
(mg/L)
1.69
1.76
2.25
2.34
2.33
2.56
2.95
1.93
1.97
2.24
Std.
Dev.
(mg/L)
0.01
0.05
0.19
0.06
0.04
0.01
0.41
0.01
0.01
0.01
Percent
Difference
(%D)
18±1.3
17 ±3.0
27 ±8.3
21 ±2.7
21 ±1.9
39 ±0.9
41 ±13
21±1.1
20±1.1
19 ±1.0
5.4 Additional Tests
5.4.1 Effect of Elevated TOC Concentration on 900 Portable Response
A minor component of this evaluation was undertaken as a control to determine if the
background TOC level had any effect on the ability of the 900 Portable to detect a change
in response to a contaminant injection. Three sets of nicotine solutions at 0.1 and 1
mg/L were injected into chlorinated water which had been fortified with quinine to raise
the background TOC level. Quinine was added to the PPL to increase the background
TOC concentration by approximately 1 mg/L. Table 5-13 presents the response
determinations from the elevated TOC injections as well as those from the injections of
nicotine at the same levels without elevated background TOC.
30
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Table 5-13. Change in 900 Portable Total Organic Carbon (TOC)with Elevated
Total Organic Carbon (TOC) Concentrations
Contaminant
Nicotine
(background
TOC)
Nicotine
(elevated
TOC)
Injected
Contaminant
Cone. (mg/L)
0.1
1
0.1
1
Average
Reference
Method
ATOC
(mg/L)
0.03
0.67
0.11
0.65
Injection 1
ATOC
(mg/L)
0.08
0.88
0.08
0.80
Std.
Dev.
(mg/L)
0.005
0.004
0.011
0.007
Injection 2
ATOC
(mg/L)
0.09
0.87
-0.01
0.80
Std.
Dev.
(mg/L)
0.005
0.005
0.017
0.007
Injection 3
ATOC
(mg/L)
0.08
0.92
0.04
0.77
Std.
Dev.
(mg/L)
0.005
0.000
0.031
0.040
Responses (indicated by shading) must be at least three times the baseline standard deviation (in table) and the average
and standard deviation of the background injection result by exhibiting a response of at least 0.03 mg/L.
The addition of quinine was observed to possibly affect the response from the 900
Portable. Without addition of quinine, all three injections at 0.1 mg/L showed a response
while, after the addition of quinine, only one of the three injections showed a response.
However, the level of the response at 1 mg/L was only slightly lower for the injections
made into the elevated background TOC water. The reference method measured a
change in TOC at 1 mg/L, but not at 0.1 mg/L.
5.4.2 Effect of Elevated Ionic Strength on 900 Portable Response
A minor component of this evaluation was undertaken as a control. Three replicate sets of
nicotine solutions at 0.1 and 1 mg/L were injected into chlorinated water which had been
fortified with calcium chloride to raise the calcium cation concentration from
approximately 42 mg/L to 126 mg/L. Grab samples collected before and after the
addition of the calcium chloride were analyzed to confirm that the calcium chloride
addition tripled the background calcium concentration.
Table 5-14. Change in 900 Portable Total Organic Carbon (TOC) with Elevated
Ionic Strength
Contaminant
Nicotine
(background
Ionic
Strength)
Nicotine
(elevated
Ionic
Strength)
Injected
Contaminant
Cone. (mg/L)
0.1
1
0.1
1
Average
Reference
Method
ATOC (mg/L)
0.03
0.67
0.01
0.23
Injection 1
ATOC
(mg/L)
0.08
0.88
-0.01
0.76
Std.
Dev.
(mg/L)
0.005
0.004
0.010
0.010
Injection 2
ATOC
(mg/L)
0.09
0.87
0.08
0.80
Std.
Dev.
(mg/L)
0.005
0.005
0.012
0.012
Injection 3
ATOC
(mg/L)
0.08
0.92
0.08
0.78
Std.
Dev.
(mg/L)
0.005
0.000
0.008
0.007
Responses (indicated by shading) must be at least three times the baseline standard deviation (in table) and the average
and standard deviation of the background injection result by exhibiting a response of at least 0.03 mg/L.
31
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Additional experiments would need to be performed to draw conclusions, but Table 5-14
presents the response determinations from the elevated ionic strength injections as well as
those from the injections of nicotine at background ionic strength.
The 900 Portable performed similarly at both ionic strengths. The only difference was
that one of the injections of nicotine at 0.1 mg/L did not produce a response in water with
elevated ionic strength. However, high concentrations of chloride interfered with the
reference measurements so a decreased reference result was obtained. The 900 Portable
was apparently less affected by the increased calcium chloride concentration while the
reference method was inhibited.
5.4.3 Effect of Monochloramine Level on 900 Portable Response
Lastly, a minor experiment was included to determine whether the level of
monochloramine had an effect on the TOC measurement from the 900 Portable. The 900
Portable was used to monitor water with three different concentrations of
monochloramine. Table 5-15 presents the 900 Portable and reference TOC measurements
for the PPL testing at monochloramine concentrations of 1.92, 5.72, and 7.54 mg/L. At
the lowest monochloramine concentration of 1.92 mg/L, the baseline 900 Portable TOC
concentration was 1.97 mg/L. For the reference method, the TOC baseline was 1.74
mg/L. Neither the 900 Portable nor the reference method responded with changes in
monochloramine concentration from 1.92 mg/L to 7.54 mg/L.
Table 5-15. Change in 900 Portable Total Organic Carbon (TOC) with Varying
Monochloramine Concentrations
Monochloramine
Concentration
(mg/L)
1.92
5.72
7.54
Reference
Method
TOC
(mg/L)
1.74
1.69
1.69
Reference
Method
ATOC
(mg/L)
Baseline
-0.05
-0.00
900
Portable
TOC
(mg/L)
1.97
1.98
1.99
900
Portable
Std. Dev.
(mg/L)
0.000
0.004
0.003
900
Portable
ATOC
(mg/L)
Baseline
0.01
0.01
Responses (indicated by shading) must be at least three times the baseline standard deviation (in table) and the average
and standard deviation of the background injection result by exhibiting a response of at least 0.03 mg/L.
5.5 Operational Characteristics
Operational characteristics of the 900 Portable that were encountered during this
evaluation are organized into the following categories:
• Training/Education Material
• Installation
• Operation
• Maintenance/Consumables/Waste
• Software/Data Collection
32
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5.5.1 Training/Educational Material
The training for operation and maintenance of the 900 Portable was a combination of
vendor provided in-person training and printed instructional material. A vendor
representative set up the 900 Portable and gave an overview of the operation, calibration,
and maintenance of the instrument. Instruction in operation of the instrument through the
front panel display was also provided.
A printed instruction manual contained information on calibration and verification
procedures as well as data retrieval and instrument operation. The manual contained
instructions for performing both scheduled and unscheduled maintenance tasks. The
manual was well organized and easy to follow. All needed test procedures were clearly
articulated in the instruction manual.
5.5.2 Installation
Installation of the 900 Portable was straight-forward. At the contractor's lab the vendor
made all necessary connections and installed the inorganic carbon removal module.
Once the instrument was up and running, the vendor performed diagnostic checks to
verify the operation of the 900 Portable. The waste line from the 900 Portable was routed
to a waste container where the waste was collected. Calibration verification was
performed by the vendor upon completion of the installation procedures.
5.5.3 Operation
After the evaluation staff had become familiar with using the 900 Portable, operation was
straight-forward. The 900 Portable was left on during periods of inactivity (overnight
and on weekends) to minimize start-up time each day. At the start of each day of testing,
the syringes were flushed prior to running tests. At the end of each day of testing,
analysis was stopped and the data file from the day was transferred to a dedicated
computer. The experimental design required these daily activities; they would not be
required in an operational setting.
5.5.4 Maintenance/Consumables/Waste
The 900 Portable required two reagents, an acid and an oxidizer, for operation. These
reagents were housed within the 900 Portable enclosure in specially constructed reagent
cartridges provided by the vendor. The acid typically lasts for six months and was not
replaced during the testing. The oxidizer has a stability of three months and was changed
once throughout the 56 days of testing. The procedure for changing the oxidizer was
clearly articulated in the instruction manual. Replacement of the oxidizer cartridge took
less than 30 minutes to complete.
The only other maintenance performed on the instrument during testing was the
replacement of the UV lamp. The lamp was provided by the vendor and replacement
33
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took approximately 15 minutes. Following replacement of the UV lamp, the 900
Portable was left on overnight and calibration was performed the following day.
All maintenance activities performed were initiated due to warning messages displayed
on the instrument's front panel. For reagents, installation and expiration dates are entered
when reagents are changed and the instrument automatically generates a message
prompting the user to change the reagent when the reagent is nearing the end of its useful
lifetime. The same process applies to replacement of the UV lamp. An automated
message was displayed on the front of the instrument prompting the user to replace the
UV lamp.
Waste from the 900 Portable was combined with the excess flow and collected in a
dedicated waste container and then disposed of. The waste and excess flow amounted to
approximately 10 L of liquid per hour of operation. During normal operation, the waste
and excess flow would be routed directly to drain without collection in a waste container.
5.5.5 Software/Data Collection
The 900 Portable software is integrated into the instrument and operated via a touch
screen on the front face. The software controls the instrument, displays the data
graphically, and stores the data for download. Data collection was initiated and stopped
using the touch screen. A separate data tab from the touch screen allowed data to be
downloaded to an USB flash drive daily. Downloaded data files were automatically
named and were saved as comma delimited text.
34
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6.0 Performance Summary
Summary results from evaluation of the 900 Portable are presented below for each
performance parameter evaluated. Discussion of the observed performance can be found
in Section 5 of this report.
6.1 900 Portable Response to Contaminant Injections
Contaminant injections were performed for aldicarb, carbofuran, colchicine, diesel fuel,
disulfoton, mevinphos, nicotine, potassium cyanide, sodium fluoroacetate, Bacillus
globigii, Bacillus thuringiensis, Chlorella, ovalbumin, and ricin. The contaminant
injection solutions were prepared within 24 hours (most within 8 hours) in the same water
that was within the PPL. Since this water contained disinfectants it could cause
degradation or transformation of the injected contaminants prior to injection. The 900
Portable responded to all three replicate injections of col chi cine and nicotine at
concentrations of 0.1 mg/L-10 mg/L in both chlorinated and chloraminated water. In
chlorinated water (Table 5-1), aldicarb was detected in two of three injections at 0.1 mg/L
and carbofuran was detected in one of three injections at 0.1 mg/L. In chloraminated
water (Table 5-2), aldicarb and carbofuran were both detected in one of three injections at
0.1 mg/L. All of the TICs were detected during every injection at 1 mg/L and above with
the exception of potassium cyanide which was detected at 1 mg/L only once each in
chlorinated and chloraminated water, but was detected in all the 10 mg/L injections. The
900 Portable did not respond to injections of Bacillus globigii or Chlorella at any injected
concentration (Tables 5-5, 5-6). Bacillus thuringiensis produced a response at 107
organisms/L for a mixture of spores and vegetative cells in both chlorinated and
chloraminated water. Ovalbumin produced a response for all injections at 0.1 mg/L, 1
mg/L, and 10 mg/L in chlorinated water and in chloraminated water produced a response
for one injection at 0.1 mg/L and all injections at 1 mg/L and 10 mg/L. Disulfoton, diesel
fuel, ricin, were analyzed only as discrete samples. For these contaminants, the 900
Portable detected a change in TOC in response to 0.1 and 1 mg/L of carbofuran in both
water matrices. Although diesel fuel was insoluble, it was added to water and analyzed
using the 900 Portable. The results, however, were inconsistent and difficult to interpret.
Disulfoton caused a TOC response at 1 mg/L in both water matrices and the 900 Portable
detected a response in TOC for ricin at 1 and 10 mg/L. In addition to these
measurements, limited experiments were performed to examine the effect of elevated
TOC, ionic strength, and monochloramine concentrations on the 900 Portable TOC
measurements.
35
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6.2 Accuracy of 900 Portable Measurements
The TOC measurements from the 900 Portable were compared with those from a
commonly used reference method and instrument during all of the contaminant injections
performed during the evaluation. These comparisons should be interpreted with the
awareness that different TOC instruments and oxidation methods can respond differently
to various contaminants. Overall, the average absolute value of the %Ds between the 900
Portable and the reference method for all the comparisons across the evaluation was 17%
± SD of 7%. For TICs in chlorinated and chloraminated water, the %Ds averaged 15% ±
5% and 14% ± 8%, respectively. For the BC, the %D averaged 19% ± SD 3% and 15%
± 6% for chlorinated and chloraminated water, respectively. For each individual
comparison, the experimental error was propagated using the uncertainty of both
measurements and is reported. Throughout the evaluation of the 900 Portable, the
propagated experimental uncertainty was typically small with respect to %D.
6.3 Operational Characteristics
During the evaluation of the 900 Portable, general operational characteristics were
observed. Installation and operation of the 900 Portable was straight forward and clearly
articulated by the vendor during a one day visit. Operation of the 900 Portable using the
touch screen on the front panel was simple and intuitive. Tests were initiated by pressing
one button and data was downloaded by following a series of on-screen prompts.
Replacement of the reagents and UV lamp were easily accomplished using the
instructions in the manual. Messages prompting the user to initiate maintenance tasks
were provided on the front panel of the 900 Portable. In the context of this evaluation,
where individual experiments lasted approximately one day, the data from the 900
Portable were easily retrieved and in a text delimited format that allowed easy transition
into a spreadsheet. This evaluation did not consider other possible data retrieval methods
(e.g. SCAD A) that could be utilized with the 900 Portable.
36
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7.0 References
1. Test/QA Plan for the Evaluation of Online Total Organic Carbon and Ultraviolet
Spectroscopy Analyzers, Technology Testing and Evaluation Program, Version 1.0,
March 19, 2009.
2. Quality Management Plan for the Technology Testing and Evaluation Program,
Version 3.0, Battelle, Columbus, Ohio, January 2008.
3. U.S. EPA, Testing and Evaluation Program. Facility Technical Standard Operating
Procedure: Chloramine Source Water Production. U.S. EPA, February 2009.
4. Hall, John; Zaffiro, Alan D.; Marx, Randall B.; Kefauver, Paul C., Krishnan, E.
Radha; Haught, Roy C.; Herrmann, Jonathan G., "On-line water quality parameters as
indicators of distribution system contamination," Journal American Water Works
Association (AWWA), (99)1, January 2007.
5. Burrows, W. Dickinson; Renner, Sara E., "Biological warfare agents as threats to
potable water," Environmental Health Perspectives, 107 (12), December 1999.
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Carbon and Specific UV Absorbance at 254 nm in Source Water and Drinking Water,
U.S. Environmental Protection Agency, National Exposure Research Lab: Cincinnati,
Ohio. EPA/600/R-05/055, February 2005.
7. U.S. EPA, EPA Method 330.5, Chlorine, Total Residual (Spectrophotometric, DPD) in
Methods for Chemical Analysis of Water and Wastes, EPA/600/4-79/020, March 1983.
8. Hach Method 10200, Nitrogen, Free Ammonia and Chloramine (Mono), Indophenol
Method (0-4.50 mg/L C12 and 0-0.50 mg/L NH3-N) for finished chloraminated
drinking water. April 2004. U.S. Patent 6,315,950, filed September 4, 1998 and
issued November 13, 2001.
9. R.C. Statt and J. A. Zeikus. 1993. Utex—the culture collection of algae at the
University of Texas at Austin. J. Phycol. 29: 1-106.
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