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The objective of this study was to see if the overall performance of the analysis could be improved by selecting specificconsumables for the instrument and incorporating a surge pressure splitless injection to lower the Detection Limits (MDLs) for U.S. Environmental Protection Agency (USEPA) Method 525.2. U.S. Environmental Protection Agency(USEPA) Method 525.2 is a general purpose method for the analysis of organic compounds in finished drinkingwater, source water, or drinking water in any stage of treatment. A one liter sample is prepared by solid phaseextraction, generating a final extract in ethyl acetate. All calibration standards are made in ethyl acetate to avoidany adverse effects caused by calibration in a different solvent from that of the extracts. The injection methodwas surge pressure splitless at an injection volume of 1 L. The mass spectrometer was set up for EI full scanfrom m/z 45 to 450. The column was programmed to elute all compounds in less than 25 minutes. Thecalibration curve was run at the following concentrations: 0.1, 0.5, 1, 2, 5, and 10 g/mL. The replicates forMDLs were run at 0.5 g/mL. The instrument system used was the DSQ II, TRACE GC Ultra, and AS 3000autosampler.After an initial evaluation of various inlet liners and column phases, the preferred liner (5 mm Splitless liner) andcolumn (TR 525 0.25 mm x 30 meter, 0.25 m) were selected for the study. The liner was selected based onproducing the lowest endrin breakdown. The column phase was selected which showed the best linearity atlevels below 0.50 g/mL, indicating minimal irreversible adsorption. The study of the preferred liner and columnshowed excellent sensitivity and met the tuning criteria for DFTPP easily from run to run. The calibration curvemet all of the QC criteria for a linear fit by average percent relative standard deviation and by least square fit fora few of the problem compounds listed in the method. In order to illustrate the performance of the system, theQuality Control criteria method tested in this study is discussed as follows: Critical Time affects GC/MS Performance;Meeting the Calibration Curve Criteria; and,Determination of MDLs or Instrument Detection Limits (IDLs).

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Edition: Vol. - No. Published: 11/01/2007 Number of Pages: 1File Size: 1 file , 93 KB