National Environmental Methods Index

Method Summary

Method Source U.S. EPA Engineering and Analysis Division Method Number 1625 Revision Information 40 CFR Part 136, Appendix A (Current Edition) Method Name Descriptive Name: Semivolatiles - Base/Neutrals, Acid Extractable, GC/MS Official Name: Semivolatile Organic Compounds by Isotope Dilution GCMS Media Media: WATER Subcategory Organic Citation EPA Method Guidance CD-ROM (includes MCAWW Methods, and most current EPA Methods) Method Download Download full method now (PDF file) Summary of Method Stable isotopically labeled analogs of the compounds of interest are added to a 1-L wastewater sample. The sample is extracted at pH 12-13, then at pH <2 with methylene chloride using continuous extraction techniques. The extract is dried over sodium sulfate and concentrated to a volume of 1 mL. An internal standard is added to the extract and the extract is injected into the GC. The compounds are separated by GS and detected by MS. The labeled compounds serve to correct the variability of the analytical technique. Scope and Application This method is designed to determine the semivolatile toxic organic pollutants associated with the 1976 Consent Decree and additional compounds amenable to extraction and analysis by capillary column gas chromatography-mass spectrometry (GC/MS). Applicable Concentration Range Varies with analyte. Interferences (A) Artifacts: Solvents, reagents, glassware, and other sample processing hardware may yield artifacts and/or elevated baselines causing misinterpretation of chromatograms and spectra. Use of pure or purified reagents and solvent rinsed and baked glassware can minimize potential for artifacts. (2) Matrix: Interferences coextracted from samples will vary considerably from source to source, depending on the diversity of the industrial complex or municipality being sampled. QC Requirements The minimum QC requirements consist of an initial demonstration of laboratory capability, analysis of samples spiked with labeled compounds to evaluate data quality, and analysis of standards and blanks as tests of continued performance. Laboratory performance is compared against established criteria. Sample Handling Collect samples in glass containers. If chlorine is present, preserve with 80 mg sodium thiosulfate per liter of sample. Keep containers at 4oC during sampling and storage. Max Holding Time 7 days (sample prior to extraction); 40 days (extract) Relative Cost/Effort Greater than $400 Sample Prep Method(s)

Method Semivolatiles - Base/Neutrals, Acid Extractable, GC/MS has 177 analytes associated with it.