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v �.. of contamination lies r.^d whe:1 t,e c:ems:up le` e.'s are aiained (!oma• level :n31vses). To assure that a site dc,":-ition is cc©prehensive, it is ,t__oMmcnded 1!-at the Mini m u m Veraicztion A.nal'ses (1.i V.- ) listed in Tab;e I be conduced as needed to deter^ine the e1te:zt of r t^ i ^n. vll �.L� :1uL.v �- Labor^tory me,1;_dci( and `1' = r, We have conducted a survey of 65 DHS certified laboratories in C ahfortia and •'� found that there is 'wide variation in methodologies for analysis of Total Petroleum Hydrocarbons MPH) and Benzene. Tolue;e. Xylene, and Ethylbenzene (BTX&E). -� Some differences include sample size and preparation. solvents, columns and detectors used and Iapses in quality assurance. Although these variations currently ace-aunt for the differ eaces in the ability for laboratories to report consis,e. �-. �t. de.e_.able levels of the compounds. the Regional 3cards are working with the Iaborateries and State agencies to resolve this by developing consistent -� guidei:res and rl ,,tocol. The inte.lt is to produce �o '' J, r and encouraand more precise protocol -:I` is:-1 '•iIl provide more reliable data to t he tank c::ner and regulatory agencies, As shoe n in the est/analvsis table below. labs have routine analyses but c--.-" lower their dote=ion Emits by improving protocol. For instance, one laboratory in California uses a modified EPA approved 524.2 (and 8240) Me hodcic - (GCI S procedure) :o produce e-ceptiona?ly lea and accurate detection levels for both TPH and 37:i&E at a little more than half the price of the two combined. The method (focused C7'ogenics) uses liquid argon to freeze the chemicals prior to injection into the dete^or. This effectively eliminates interfering gases such as oxygen and allows the injection of 100 z of the sample into the Mass Spectrometer for analysis (as opposed to approximately 10% by the conventional purge and trap procedure). The increased sample size provides accurate detection and. because it analyzes everything at once. lowers the cost of analysis considerably. Other advantages are that EDB also is identified and second column confirmation is not needed. In the cost/analysis table the costs are based on submittal of a rather uncomplicated sample. Laboratory handling and preparation for "dirty" or complex samples may inc.-ease-ease costs up to 50.. :nd consultants may add a 15% surcharge for collecting and tri^sporting the sample, and interpreting the results. Therefore. a bill for BTX&E in soil may include $105 for the analysis • $35 for special '•ork $20 consultant fee the:eby totalling $ 16 0 (or more). 'This may not be unreasonable for the circumstances.