EPA/600/R-98/145November 1998Environmental Technology VerificationReportField-Portable Gas ChromatographSentex Systems, Inc. Scentograph Plus IIbyWayne EinfeldSandia National LaboratoriesAlbuquerque, New Mexico 87185-0755IAG DW89936700-01-0Project OfficerStephen BilletsNational Exposure Research LaboratoryOffice of Research and DevelopmentU.S. Environmental Protection AgencyLas Vegas, Nevada 89193

NoticeThe U.S. Environmental Protection Agency (EPA), through its Office of Research and Development (ORD), fundedand managed, under Interagency Agreement No. DW89936700-01-1 with the U.S. Department of Energy s SandiaNational Laboratory, the verification effort described in this document. This report has received both technical peerand administrative policy reviews and has been approved for publication as an EPA document. Mention ofcorporate names, trade names, or commercial products does not constitute endorsement or recommendation for use.ii

UNITED STATES ENVIRONMENTAL PROTECTION AGENCYOffice of Research and DevelopmentWashington, D.C. 20460ENVIRONMENTAL TECHNOLOGY VERIFICATION PROGRAMVERIFICATION STATEMENTTECHNOLOGY TYPE:FIELD-PORTABLE GAS CHROMATOGRAPHAPPLICATION:MEASUREMENT OF CHLORINATED VOLATILE ORGANICCOMPOUNDS IN WATERTECHNOLOGY NAME:Scentograph Plus IICOMPANYADDRESS:Sentex Systems, Inc.553 Broad Ave.Ridgefield, NJ 07657PHONE:(201) 945-3694PROGRAM DESCRIPTIONThe U.S. Environmental Protection Agency (EPA) created the Environmental Technology Verification (ETV)Program to facilitate the deployment of innovative environmental technologies through performance verification andinformation dissemination. The goal of the ETV Program is to further environmental protection by substantiallyaccelerating the acceptance and use of improved and cost-effective technologies. The ETV Program is intended toassist and inform those involved in the design, distribution, permitting, and purchase of environmental technologies.Under this program, in partnership with recognized testing organizations, and with the full participation of thetechnology developer, the EPA evaluates the performance of innovative technologies by developing demonstrationplans, conducting field tests, collecting and analyzing the demonstration results, and preparing reports. The testingis conducted in accordance with rigorous quality assurance protocols to ensure that data of known and adequatequality are generated and that the results are defensible. The EPA National Exposure Research Laboratory, incooperation with Sandia National Laboratories, the testing organization, evaluated field-portable systems formonitoring chlorinated volatile organic compounds (VOCs) in water. This verification statement provides asummary of the demonstration and results for the Sentex Systems, Inc. Scentograph Plus II, field-portable gaschromatograph (GC).DEMONSTRATION DESCRIPTIONThe field demonstration of the Scentograph Plus II portable GC was held in September 1997. The demonstrationwas designed to assess the ability of the instrument to detect and measure chlorinated VOCs in groundwater at twocontaminated sites: the Department of Energy’s Savannah River Site, near Aiken, South Carolina, and theMcClellan Air Force Base, near Sacramento, California. Groundwater samples from each site were supplementedwith performance evaluation (PE) samples of known composition. Both sample types were used to assessinstrument accuracy, precision, sample throughput, and comparability to reference laboratory results. The primarytarget compounds at the Savannah River Site were trichloroethene and tetrachloroethene. At McClellan Air ForceBase, the target compounds were trichloroethene, tetrachloroethene, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,2-EPA-VS-SCM-27The accompanying notice is an integral part of this verification statementiiiNovember 1998

dichloropropane, and trans-1,3-dichloropropene.These sites were chosen because they contain variedconcentrations of chlorinated VOCs and exhibit different climatic and geological conditions. The conditions at thesesites are typical, but not inclusive, of those under which this technology would be expected to operate. A completedescription of the demonstration, including a data summary and discussion of results, may be found in the reportentitled Environmental Technology Verification Report, Field-Portable Gas Chromatograph, Sentex Systems,Inc., Scentograph Plus II. (EPA/600/R-98/145).TECHNOLOGY DESCRIPTIONGas chromatography with electron capture detection is a proven analytical technology that has been used inenvironmental laboratories for many years. The gas chromatographic column separates the sample into individualcomponents. The electron capture detector measures a change in electron current from a sealed radioactive source ascompounds exit the chromatographic column, move through the detector, and capture electrons. The electroncapture detector is particularly sensitive to chlorinated compounds. Compound identification is achieved bymatching the column retention time of sample components, run under controlled temperature conditions, to those ofstandard mixtures run under similar conditions. Quantitation is achieved by comparing the detector responseintensity of sample component and standard. A GC offers some potential for identification of unknown componentsin a mixture; however, a confirmational analysis by an alternative method is often advisable. Portable GC is aversatile technique that can be used to provide rapid screening data or routine monitoring of groundwater samples.In many GC systems, the instrument configuration can also be quickly changed to accommodate different samplematrices such as soil, soil gas, water, or air. As with all field analytical studies, it may be necessary to send aportion of the samples to an independent laboratory for confirmatory analyses.The Scentograph Plus II consists of three modules: a purge-and-trap unit, a GC, and a notebook computer forinstrument control and data acquisition. The entire system weighs about 80 pounds and is about the size of a largesuitcase. The units can be easily transported and operated in the rear compartment of a minivan or station wagon.Instrument detection levels for most chlorinated VOCs in water range from 0.1 to 50 mg/L. Sample processing andanalysis can be accomplished by a chemical technician; however, instrument method development, instrumentcalibration, and data processing require a higher level of operator experience and training. The recommendedtraining interval for routine sample processing is 1 day for a field technician with limited GC experience. At the timeof the demonstration, the baseline cost of the Scentograph Plus II was 35,000. Operational costs, which take intoaccount consumable supplies, are on the order of 25 per 8-hour day.VERIFICATION OF PERFORMANCEThe following performance characteristics of the Scentograph Plus II were observed:Sample Throughput: Throughput was about two samples per hour. This rate includes the periodic analysis ofblanks and calibration check samples. The sample throughput rate is influenced by the complexity of the sample,with less complex samples yielding higher throughput rates.Completeness: The Scentograph Plus II reported results for all 165 PE evaluation and groundwater samplesprovided for analysis at the two demonstration sites.Analytical Versatility: The Scentograph Plus II was calibrated for and detected 59% (19 of 32) of the PE sampleVOC compounds in the PE samples provided for analysis at the demonstration. Three pairs of coeluting compoundswere encountered with the GC methods used during this demonstration. For the groundwater contaminantcompounds for which it was calibrated, the Scentograph Plus II detected 35 of the 62 compounds reported by thereference laboratory at concentration levels in excess of 1 mg/L. A total of 68 compounds were detected by thereference laboratory in all groundwater samples.Precision: Precision was determined by analyzing sets of four replicate samples from a variety of PE mixturescontaining known concentrations of chlorinated VOCs. The results are reported in terms of relative standarddeviations (RSD). The RSDs compiled for all reported compounds from both sites had a median value of 8% and aEPA-VS-SCM-27The accompanying notice is an integral part of this verification statementivNovember 1998

95th percentile value of 32%. By comparison, the compiled RSDs from the reference laboratory had a median valueof 7% and a 95th percentile value of 25%. The ranges of Scentograph Plus II RSD values for specific targetcompounds were as follows: trichloroethene, 0 to 17%; tetrachloroethene, 3 to 28%; 1,2-dichloropropane, 5 to12%; 1,1,2-trichloroethane, 6 to 24%; trans-1,3-dichloropropene, 4 to 29%; and 1,2-dichloroethane, 6 to 36%.Accuracy: Instrument accuracy was evaluated by comparing Scentograph Plus II results with the knownconcentrations of chlorinated VOCs in PE mixtures. Absolute percent difference (APD) values from both sites werecalculated for all reported compounds in the PE mixtures. The APDs from both sites had a median value of 10% anda 95th percentile value of 38%. By comparison, the compiled APDs from the reference laboratory had a medianvalue of 7% and a 95th percentile value of 24%. The ranges of Scentograph Plus II APD values for targetcompounds were as follows: trichloroethene, 1 to 24%; tetrachloroethene, 0 to 15%; 1,2-dichloropropane, 2 to 22%;1,1,2-trichloroethane, 3 to 16%; trans-1,3-dichloropropene, 0 to 24%; and 1,2-dichloroethane, 3 to 78%.Comparability: A comparison of Scentograph Plus II and reference laboratory data was based on 33 groundwatersamples analyzed at each site. The correlation coefficient (r) for all compounds detected by both the ScentographPlus II and laboratory at or below the 100 mg/L concentration level was 0.974 at Savannah River and 0.959 atMcClellan. The r values for compounds detected at concentration levels in excess of 100 mg/L were 0.907 forSavannah River and 0.997 for McClellan. These correlation coefficients reveal a highly linear relationship betweenScentograph Plus II and laboratory data. The median APD between groundwater compounds mutually detected bythe Scentograph Plus II and the reference laboratory was 12% with a 95th percentile value of 194%.Deployment: The system was ready to analyze samples within 60 minutes of arrival at the site. At both sites, theinstrument was transported in a minivan and operated from its folded middle seat. The instrument was powered byline ac or from a small dc-to-ac inverter connected to the vehicle’s battery.The results of the demonstration show that the Sentex Systems, Inc., Scentograph Plus II field-portable GC withelectron capture detector can provide useful, cost-effective data for environmental site screening and routinemonitoring. This instrument could be employed in a variety of applications, ranging from producing rapid analyticalresults in screening investigations, to producing accurate and precise data that are directly comparable with thatobtained from an off-site laboratory. These data could be used to develop risk assessment information, support aremediation process, or fulfill monitoring requirements. In the selection of a technology for deployment at a site, theuser must determine what is appropriate through consideration of instrument performance and the project’s dataquality objectives.Gary J. Foley, Ph. D.DirectorNational Exposure Research LaboratoryOffice of Research and DevelopmentSamuel G. VarnadoDirectorEnergy and Critical Infrastructure CenterSandia National LaboratoriesNOTICE: EPA verifications are based on an evaluation of technology performance under specific, predetermined criteriaand the appropriate quality assurance procedures. EPA makes no expressed or implied warranties as to the performance ofthe technology and does not certify that a technology will always, under circumstances other than those tested, operate atthe levels verified. The end user is solely responsible for complying with any and all applicable federal, state and localrequirements.EPA-VS-SCM-27The accompanying notice is an integral part of this verification statementvNovember 1998

ForewordThe U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the nation’s naturalresources. The National Exposure Research Laboratory (NERL) is the EPA center for the investigation oftechnical and management approaches for identifying and quantifying risks to human health and the environment.The NERL research goals are to (1) develop and evaluate technologies for the characterization and monitoring ofair, soil, and water; (2) support regulatory and policy decisions; and (3) provide the science support needed toensure effective implementation of environmental regulations and strategies.The EPA created the Environmental Technology Verification (ETV) Program to facilitate the deployment ofinnovative technologies through verification of performance and dissemination of information. The goal of the ETVProgram is to further environmental protection by substantially accelerating the acceptance and use of improvedand cost-effective technologies. It is intended to assist and inform those involved in the design, distribution,permitting, and purchase of environmental technologies.Candidate technologies for this program originate from the private sector and must be market ready. Through theETV Program, developers are given the opportunity to conduct rigorous demonstrations of their technologies underrealistic field conditions. By completing the evaluation and distributing the results, the EPA establishes a baselinefor acceptance and use of these technologies.Gary J. Foley, Ph. D.DirectorNational Exposure Research LaboratoryOffice of Research and Developmentvi

Executive SummaryThe U.S. Environmental Protection Agency, through the Environmental Technology Verification Program, isworking to accelerate the acceptance and use of innovative technologies that improve the way the United Statesmanages its environmental problems. As part of this program, the Consortium for Site CharacterizationTechnology was established as a pilot program to test and verify field monitoring and site characterizationtechnologies. The Consortium is a partnership involving the U.S. Environmental Protection Agency, theDepartment of Defense, and the Department of Energy. In 1997 the Consortium conducted a demonstration of fivetechnologies designed for the analysis of chlorinated volatile organic compounds in groundwater. The developersparticipating in this demonstration were: Electronic Sensor Technology, Perkin Elmer-Photovac, and SentexSystems, Inc. (field-portable gas chromatographs); Innova AirTech Instruments (photoacoustic infrared analyzer);and Inficon, Inc. (field-portable gas chromatograph/mass spectrometer). This report documents demonstrationactivities, presents demonstration data, and verifies the performance of the Sentex Scentograph Plus II field portable gas chromatograph. Reports documenting the performance of the other technologies have been publishedseparately.The demonstration was conducted at two geologically and climatologically different sites: the U.S. Department ofEnergy’s Savannah River Site, near Aiken South Carolina and McClellan Air Force Base, near SacramentoCalifornia. Both sites have groundwater resources that are significantly contaminated with a variety of chlorinatedvolatile organic compounds. The demonstrations designed to evaluate the capabilities of each field-transportablesystem were conducted in September 1997 and were coordinated by Sandia National Laboratories.The demonstration provided adequate analytical and operational data with which to evaluate the performance of theScentograph Plus II gas chromatograph. Instrument precision and accuracy were determined by an analysis ofreplicate samples from 16 multicomponent standard mixtures of known composition. The relative standarddeviations, obtained from an analysis of 4 replicate samples from each of the 16 standard mixtures, were used asmeasures of precision. The relative standard deviations from all compounds had a median value of 8% and a 95thpercentile value of 32%. Accuracy was expressed as the absolute percent difference between the Scentograph PlusII measured value and the true value component in the standard mixtures. The distribution of absolute percentdifferences for all reported compounds had a median value of 10% and a 95th percentile value of 38%. Acomparison of Scentograph Plus II and reference laboratory results from 33 groundwater samples at each siteresulted in a median absolute percent difference of 12% with a 95th percentile value of 194%. A correlationanalysis between Scentograph Plus II and laboratory results resulted in correlation coefficients (r) greater than 0.96at low ( 100 mg/L) contaminant concentrations. Correlation coefficients were greater than 0.91 at high ( 100 mg/L) contaminant concentrations. The sample throughput rate of the Scentograph Plus II was determined to be twosamples per hour. The Scentograph Plus II costs about 35,000 for a single-detector, single-column configuration,and can be operated by a field technician with minimal training in gas chromatography.Under appropriate applications, the Scentograph Plus II can provide useful, cost-effective data for environmentalsite characterization and routine monitoring. As with any technology selection, the user must determine whether thetechnology is appropriate for the application by taking into account instrument performance and the project’s dataquality objectives.vii


ContentsNotice . iiVerification Statement . iiiForeword . viExecutive Summary . viiFigures. xiiiTables. xivAcronyms and Abbreviations. xvAcknowledgments . xviiChapter 1 Introduction. 1Site Characterization Technology Challenge. 1Technology Verification Process . 2Identification of Needs and Selection of Technology. 2Planning and Implementation of Demonstration. 2Preparation of Report . 3Distribution of Information. 3The Wellhead VOC Monitoring Demonstration . 3Chapter 2 Technology Description. 5Technology Overview . 5Principle of Operation. 6Instrument Description. 6Operational Mode. 6Detector Systems. 7Sample Injection. 8History of the Technology. 8Applications . 9Advantages. 9ix

Limitations . 9Performance Characteristics . 9Method Detection Limits . 9Practical Quantitation Limit . 9Accuracy. 10Precision . 10Instrument Working Range. 10Comparison with Reference Laboratory Analyses . 10Data Completeness. 10Specificity. 10Other Field Performance Characteristics . 11Instrument Setup and Disassembly Time. 11Instrument Calibration Frequency. 11Ancillary Equipment Requirements. 11Field Maintenance Requirements . 11Sample Throughput Rate. 11Ease of Operation. 11Chapter 3 Demonstration Design and Description . 12Introduction. 12Overview of Demonstration Design. 12Quantitative Factors . 12Qualitative Factors . 13Site Selection and Description. 14Savannah River Site . 14McClellan Air Force Base . 16Sample Set Descriptions . 18PE Samples and Preparation Methods. 21Groundwater Samples and Collection Methods . 23Sample Handling and Distribution. 23Field Demonstration Schedule and Operations. 24Site Operations and Environmental Conditions . 24Field Audits. 25x

Data Collection and Analysis . 26Demonstration Plan Deviations . 26Chapter 4 Laboratory Data Results and Evaluation. 27Introduction. 27Reference Laboratory . 27Laboratory Selection Criteria. 27Summary of Analytical Work by DataChem Laboratories . 28Summary of Method 8260A. 28Method 8260A Quality Control Requirements. 28Summary of Laboratory QC Performance . 28Target Compound List and Method Detection Limits . 29Sample Holding Conditions and Times. 29System Calibration . 29Daily Instrument Performance Checks . 31Batch-Specific Instrument QC Checks . 31Sample-Specific QC Checks. 31Summary of Analytical and QC Deviations. 33Other Data Quality Indicators . 33PE Sample Precision . 34PE Sample Accuracy. 34Groundwater Sample Precision. 39Summary of Reference Laboratory Data Quality. 40Chapter 5 Demonstration Results. 41Scentograph Plus II Calibrated and Reported Compounds . 41Preanalysis Sample Information. 41Sample Completion. 42Blank Sample Results. 42Performance at Method Detection Limit . 42PE Sample Precision. 42PE Sample Accuracy . 45xi

Comparison with Laboratory Results .

Sentex Systems, Inc. Scentograph Plus II. by. Wayne Einfeld Sandia National Laboratories Albuquerque, New Mexico 87185-0755. IAG DW89936700-01-0. Project Officer. Stephen Billets. National Exposure Research Laboratory Office of Research and Development U.S