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collected and analyzed for target compounds. Trip blanks,consisting of humidified F-5 QUALITY ASSURANCEIQUALITY CONTROL IQAIQC) laboratory grade ultra pure air,are prepared to evaluate if the shipping and handling procedures are introducing contaminants into the samples and if cross-contamination QA/QC requirements for soil gas testing are either outlined in the specific project Quality in the form of VOC migration has occurred between the collected VOC samples. The Assurance Project Plan(QAPP)or the specific modified EPA Method being employed. trip blank containers and media should be the same as the site samples. For Soil gas analytical laboratories,at minimum should comply with those QA/QC passivated stainless steel canisters(e.g.,SUMMA*canisters),trip blanks are not requirements and add additional checks as needed. necessary since it is unlikely that VOCs will migrate in or out of or between canisters unless a specific canister is not tightened properly by the sample handler. QA/QC FOR SOIL GAS TESTING Additionally,EPA Method TO-15 does not have specific trip blank requirements. Therefore,trip blanks are not recommended if samples are collected in passivated The following are the minimum QA/QC protocols that should be included with soil gas stainless steel canisters unless specified in the QAPP or by the project manager. • testing. Most of these QA/QC protocols are required with EPA methods and as well as laboratory certification(see later). Duplicate Samples:At least one duplicate sample per 20 samples or per batch, whichever is more often,should be collected and analyzed. Duplicate samples • Daily Tune:For GC/MS methods,laboratories should conduct the daily tune(i.e., should be collected in separate containers at the same location and depth. A BFB for VOCs and DFTPP for SVOC)as specified in the respective method. The duplicate sample can be collected by use of a splitter(T)at the point of collection to instrument must meet the tuning criteria before sample analysis. divide the sample stream into two separate sample containers. This sample analysis is designed to evaluate the reproducibility(precision)of the sampling process. • Initial Calibration:The calibration curve should consist of a minimum of 5 points. The maximum percent relative standard deviation(%RSD)for each target compound Replicate Samples:At least one replicate sample per 20 samples or per batch, should not exceed 30%. whichever is more often,should be re-analyzed by the laboratory to assess analytical precision. This is not to be confused with the duplicate sample mentioned above. • Daily Calibration(Continuing calibration):The calibration curve for each compound of This is designed to evaluate the reproducibility(precision)of the laboratory's interest should be verified with each analytical batch or once very 12 hours, analytical ability. - whichever is more often. Verification is conducted by analyzing the mid-point calibration standard. The results from the mid-point standard should be within 20% Matrix Spike/Matrix Spike Duplicates(MS/MSD):Although MS/MSD samples are (percent difference)of the initial calibration in order to assume the calibration curve is required with the EPA 8000 series method,there is no practical approach to apply valid. this requirement to soil gas samples. For really true MS/MSD samples,spike compounds must be added to the sample during the collection process.With soil gas • Method Blanks:Method blanks are used to evaluate contamination from the samples,this is not technically feasible. The addition of a spike into the sparger with analytical process. This is a sample prepared by the analytical laboratory using an modified EPA Method 8260B/C does not duplicate the actual condition of the sample analyte-free matrix(for soil is humidified laboratory grade ultra pure air)and carried as it is collected,processed and analyzed. Therefore,the requirement for MS/MSD through the entire sample preparation and analytical procedure. with modified EPA Method 8260BIC is discretionary. There is no requirement for MS/MSD with EPA Method TO-15 as the analysis of MS/MSD with TO-15 is • • Container Blanks: (This was called the"Method Blank"in the previous version of the impractical, Spike compounds are added at the same time when the sample is soil gas advisory.) If sampling containers(e.g.,glass syringes,glass bulbs)are transferred into the concentrator. This does not truly assess the impact of the matrix reused/recycled,then at least one(1)decontaminated sample container per 20 on the recovery of the target compounds. Therefore,the need for MS/MSD with samples or per batch,whichever is more often,should be analyzed as a container Method TO-15 is at the discretion of the parties involved in the project and should be blank sample to verify the effectiveness of the decontamination procedures. based on the data quality objectives. Additional note: Other components of the sampling stream(e.g.,fittings/valves)that are subject to carryover/contamination should also be monitored. • Laboratory Control Sample(LCS):LCS is required with the EPA 8000 series methods. LCS is a sample made with an aliquot of a clean(control)matrix similar to • Trip Blanks: (ONLY REQUIRED IF SAMPLES ARE COLLECTED IN TEDLAR® the sample matrix spiked with compounds that are representative of the target BAGS OR SORBENT TUBES FOR TO-17 ANALYSIS)Whenever VOC samples are analytes. It is used to document laboratory performance. This is similar to MS/MSD shipped offsite for analysis,a minimum of one(1)trip blank per day should be without the possibility of any matrix interference. For soil gas analysis,this QA/QC 12/10/2009 -81 - 12/10/2009 -82-