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I have read Leticia's email dated June 23, 2010, concerning questions I presented by email <br /> dated May 12, 2010, and I want to thank Leticia for taking the time to review and respond <br /> to the analytical data from Cal Tech Environmental Laboratories. <br /> Based on Leticia's comments, I have concluded the following: <br /> 1. Identical laboratory results submitted for three soil gas samples (VP-1, VP-2, <br /> and VP-3) , first reported for individual analytes by method TO-15, and TPH--gasoline and <br /> TPH-diesel by TO-3, then later reported for TPH-gasoline and individual analytes by EPA <br /> 8260B, and TPH-diesel by EPA 8015M, are acceptable. <br /> 2 . I will send a letter requesting that the laboratory provide a hard copy of the <br /> GC/MS chromatograms for the initial calibration curve, the continuing calibration <br /> standards, method blanks, LCS/LCSD, and MS/MSD for TPH-diesel that are associated with <br /> these three soil gas <br /> samples. <br /> 3. I will request clarification to the statement "On review of the analytical data <br /> with the laboratory and review of GCMS methodology; gasoline range organic (GRO) response <br /> from the EPA 8260B analysis for these samples was superior in detections of volatile <br /> compounds when compared to the response for EPA 8015M method; otherwise the reported <br /> concentrations of TPH-GRO reported by EPA method 8015M would have been diminished from the <br /> reported concentrations by EPA 8260B. " <br /> If Leticia is in disagreement with these conclusions, please let me know. <br /> Thank you, Jim. <br /> Vicki McCartney, Senior REHS <br /> San Joaquin County <br /> Environmental Health Department <br /> 600 East Main Street <br /> Stockton, California 95202 <br /> Phone: (209) 468-9852 <br /> Fax: (209) 468-3433 <br /> Email : vmccartney@sjcehd.com <br /> -----Original Message----- <br /> From: Jim Barton [mailto:jbarton@waterboards.ca.gov] <br /> Sent: Thursday, June 24, 2010 6:12 AM <br /> To: Vicki McCartney [EH] ; Leticia Valadez <br /> Subject: Re: Fwd: RE: Evaluation of Analytical Methods by theRegionalBoard'sChemist <br /> Thanks Leticia. <br /> Hi Vicki, <br /> Please read below and respond whether this answers your questions. <br /> Thanks. <br /> Jim Barton <br /> »> Leticia Valadez 6/23/2010 8 :13 AM »> <br /> Can the laboratory report soil gas concentrations in ug/m3 by "modified" <br /> method 8260B, and "modified" method 8015M when the QA/QC units are reported in ug/L ? <br /> Yes through conversion from ug/m3 to ug/L. <br /> Can the lab report TPH-diesel concentrations without a continuing calibration standard for <br /> TPH-diesel? <br /> GCs are calibrated for all target compounds prior to the analysis of samples. Typically, a <br /> five point calibration curve is used, depending on the specific methodology. The multi- <br /> point calibration curve is used to determine the instrument's linear range, average <br /> response factors, average retention time windows and average peak heights or average peak <br /> area for all target compounds being analyzed. On a daily basis, continuing calibration is <br /> verified by using a calibration verification standard, which is usually prepared at the <br /> midpoint of the multi-point calibration curve. Continuing calibration standards are <br /> prepared from a source independent of the multi-point calibration standard. Performance <br /> criteria for calibration, as defined in the specific methodology, must be met prior to the <br /> 3 <br />