NEMI Method Summary

Method Summary Information

Method Number: 1624 Media: WATER
Revision: 40 CFR Part 136, Appendix A (Current Edition)
Method Source: U.S. EPA Engineering and Analysis Division
Subcategory: ORGANIC Analytes in this method
Official Name: Method 1624, Revision B: Volatile Organic Compounds by Isotope Dilution GC/MS
Descriptive Name Volatile Organic Compounds by GC/MS
Source Info: 4303 USEPA Headquarters
Ariel Rios Building
1200 Pennsylvania Avenue, N. W.
Washington, DC 20460
Citation: EPA Method Guidance CD-ROM (includes MCAWW Methods, and most current EPA Methods)
127627 Byte file
Brief Method
Summary:
 Stable isotopically labeled analogs of the compounds of interest are added to a 5 mL water sample. The sample is purged at 20-25oC with an inert gas where the volatile organic compounds are transferred from the aqueous phase into the gaseous phase and passed into a sorbent column and trapped. After purging is completed, the trap is backflushed and heated rapidly to desorb the compounds into a gas chromatograph (GC) where they are separated and detected by a mass spectrometer (MS).
Scope And
Application:
 This method determines the volatile toxic organic pollutants that are amenable to purge and trap gas chromatography-mass spectrometry (GC-MS).
Applicable
Conc Range:
 Not Available.
Interferences: (A) Analytical system: Impurities in the purge gas, organic compounds out-gassing from the plumbing upstream of the trap, and solvent vapors can interfere.
(B) Sample contamination: Samples can be contaminated by diffusion of volatile organic compounds through the bottle seal during shipment and storage.
(C) Carry-over: Rinse the purging device and sample syringe with reagent water between samples.
QC Requirements: The minimum requirements consist of an initial demonstration of laboratory capability, analysis of samples spiked with labeled compounds to evaluate and document data quality, and analysis of standards and blanks as tests of continued performance.
Sample Handling: Collect grab samples in glass containers having a total volume greater than 20 mL. Make sure no air bubbles are entrapped and maintain the hermetic seal until analysis. Store at 0-4oC from time of collection until analysis. If residual chlorine is present, add 10mg/40mL of sodium thiosulfate prior to collection. Adjust pH to about 2 by adding HCl (1+1) while stirring.
Max Holding Time:
 14 days (after collection)
Sample Prep Met None.
Relative Cost: Greater than $400
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