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2 <br />for future analysis that we discussed before still holds true. If you want to discuss any of this off-line from the RP, just let <br />me know and I would be happy to do so. <br /> <br />I hope the test and surgery both went well and that y’all are feeling good this week. <br /> <br />See you soon, <br /> <br />Patrick F <br /> <br /> <br />From: Wilson, Patrick <Wilson.Patrick@epa.gov> <br />Sent: Monday, July 19, 2021 7:06 PM <br />To: Frier, William <Frier.William@epa.gov> <br />Subject: RE: Lab Reports 12701, 12751, and 13670 - Cogen <br /> <br />I see. Good follow up on your part. <br /> <br />This maybe a methods difference as you suspect. I’m not familiar with the other method (I’ll look into) – but you should <br />confirm during the call that the limits of detection for the media in question are low enough to detect the dioxins & <br />furans at RSLs concentrations? <br /> <br />Again – our RSLs for these constituents are in the low ppt range. <br /> <br />Final uncertainty: it appears the analytical method referenced only detects a subset of the family of dioxins, and only a <br />subset of the family of furans congeners? That’s somewhat odd in that our decision making is contingent on the total <br />concentration of all congeners in the constituent mix. That is to say – we are not only concerned with the highly <br />chlorinated congeners as the analytical method title seems to suggest – we would want to examine the total number of <br />congeners – including the lower chlorinated congener members of each separate family (PCB, dioxin, furan). <br /> <br />Keep in mind – these methods can be used to simply add up the concentration of each congener from each of the three <br />families of chemicals into a total, yet separate concentration for each. <br /> <br />Think of it as dioxin family total congener concentration of xxx ppt. Then furan family total congener concentration of <br />xxx ppt. Then our PCB family (w/206 individual members or congeners) as xxx ppt. <br /> <br />Best wishes for your call….. <br /> <br />From: Frier, William <Frier.William@epa.gov> <br />Sent: Monday, July 19, 2021 6:35 PM <br />To: Wilson, Patrick <Wilson.Patrick@epa.gov> <br />Subject: Re: Lab Reports 12701, 12751, and 13670 - Cogen <br /> <br />Thank you so much for that description! I think the issue may be that they used a different method to analyze <br />the dioxins and furans (method 1613B - Tetra through Octa-Chlorinated Dioxins and Furans by Isotope Dilution <br />HRGC/HRMS). Both Method 1613 and Method 1668 use HRGC/HRMS, but I cannot tell if what you said about <br />Method 1668 would also hold true if the RP used Method 1613. Do you know? <br /> <br />I can certainly request, after coordinating with the Water Board, that they us e Method 1668 for future analysis <br />of the dioxins and furans so that we can also get the PCB congener info. Either way - thank you, this is super <br />helpful.