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R9 Laboratory SOP 354
Volatile Organics Analysis (524.2 Reference Method)
Summary
This Standard Operating Procedure (SOP) describes the procedures used for the analysis of volatile organic compounds in the Region 9 Laboratory. The procedures reference EPA method 524.2. The compounds which may be determined using this SOP are listed in Appendix B.This SOP is applicable to the analysis of surface water, ground water, and drinking water for volatile organic compounds (VOC) in support of the EPA's Superfund, RCRA, WQM, NPDES, UIC, and SDWA programs. The applicability of these procedures to specific project data quality objectives must be assessed on a case by case basis. The QC criteria specified in this SOP meet compliance criteria for drinking water or NPDES monitoring projects.
VOCs are purged from a 25mL water sample in a fritted sparge cell. An inert gas (helium) is bubbled through the sample in the sparge cell, which causes the purgeable VOCs to be transferred from the aqueous sample to the vapor phase. The vapor phase is swept through a trap, containing an adsorbent material at ambient temperature, where the VOCs are trapped.
After the purging of the sample is completed, the adsorbent trap is heated and back flushed with helium which desorbs the VOCs onto a capillary column in a gas chromatograph (GC). The VOCs are separated in the GC column and detected by a mass spectrometer.
The samples are fortified with internal standards (IS) and surrogate compounds (SUR) before they are purged. The target volatile organic compounds and surrogate compounds are identified in the sample by analyzing standards under the exact same conditions employed for samples, and comparing the resulting mass spectra and GC retention times. A response factor is established for each target and surrogate compound during the initial and continuing calibrations by comparing the MS response of the primary ion produced by the target and surrogate compounds to the MS response for the primary ion produced by the associated internal standard. Each target and surrogate compound is quantitated by comparing the responses of the target and surrogate compound responses to the internal standard responses, using the average response factors from the most recent initial calibration.