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it <br /> ! tt� <br /> If , <br /> February 23 , 1993 <br /> 1 Bob .Marty <br /> Geological Audit Services - <br /> Re: Sample Log 5676 j <br /> i <br /> Dear Mr. Marty, <br /> The accepted method of quantification for Total Petroleum <br /> Hydrocarbons as Gasoline (TPH=G) involves adding up all <br /> 'peaks' that are detected by the FlamejIonlfization Detector <br /> (FID) during the gas chromatographic run. ;When the pattern <br /> of peaks for a sample does not match the normal pattern of <br /> peaks that gasoline produces, it is our practice to flag the <br /> data with an asterisk and make the following annotation: <br /> ' "Product is not typical gasoline. " <br /> Often, chlorinated solvents exist in sample's that are being <br /> analyzed for TPH-G. They are detectedliby the FID and <br /> therefore are counted as TPH-G. The pattern that chlorinated <br /> solvents produce is very distinct from iigasoline since they <br /> are single compounds and produce single peaks. Gasoline is . <br /> made up of many compounds and producesmany peaks. <br /> �I h <br /> In the case of your sample, the TPH-G dataUs flagged because <br /> the chlorinated solvents present in the sample are causing <br /> the Il data to be greater than 'not detected' even though <br /> there is no qualitative evidence that gasol.ine. exists in the <br /> sample. <br /> If you have any further questions, please call me. <br /> sincerely, <br /> 1�3 II1 <br /> E <br /> Joel Kiff - <br /> WEST Laboratory <br /> Western Environmental Science & Technology 45133 County Road 329 Davis, CA 95616 - 916 753-9500 FAX: 916 757-4652 1 <br />