EPA-EAD: 624:  Purgeable Organic Compounds via GC/MS

  • Summary
  • Analytes
  • Revision
  • Data and Sites
Official Method Name
Purgeables
Current Revision
40 CFR Part 136, Appendix A (Current Edition)
Media
WATER
Instrumentation
Gas Chromatography with Mass Spectrometry Detection
Method Subcategory
Organic
Method Source
  EPA-EAD
Citation
  EPA Method Guidance CD-ROM (includes MCAWW Methods, and most current EPA Methods)
Brief Method Summary
A sample is purged with an inert gas transforming the purgeable organics to the vapor phase where it is collected on an absorbent trap at ambient temperature. After the sample is purged, the trap is then heated, backflushed, and desorbed with the inert gas onto an chromatographic column. The gas chromatograph is temperature programmed to separate the purgeable organics, which are then detected by a mass spectrometer (MS).
Scope and Application
This is a GC/MS method that determines the quantity of purgeable organics. This method can also be extended to screen for acrolein (CAS No. 107-02-8) and acrylonitrile (CAS No. 107-13-1), however the preferred method for these two compounds is Method 603.
Applicable Concentration Range
Varies based on analyte and conditions (ug/L).
Interferences
(A) Impurities in gas and plumbing: Impurities in the inert gas and organic plumbing system of the purge and trap concentrator tend to be the main cause of interference in the analytical system. The use of non-Teflon tubing and fittings should be avoided.
(B) Contamination during collection: Samples can become contaminated by diffusion of volatile organic compounds (especially methylene chloride and fluorocarbons) across the septum seal during collection and storage. Use Field Blanks to verify possible contamination.
(C) Carryover: Contamination by carry-over in the analytical system can occur, especially in sample that are extremely concentrated. Frequent bakeout and cleaning of the purging system can help prevent carry-over.
Quality Control Requirements
Initial demonstration of laboratory capability and the periodic analysis of laboratory reagent blanks, fortified blanks, and other laboratory solutions as a continuing check on performance.
Sample Handling
Sample should be placed in a 25mL glass vial or larger, screw cap with a hole in the center for a Teflon-faced silicone septum. The sample should not have a headspace and should be kept refrigerated until analysis. If the sample is believed to contain free or combined chlorine, add 10mg/40mL of sodium thiosulfate upon collection and shake vigorously for one minute.
Maximum Holding Time
14 days.
Relative Cost
$201 to $400
Sample Preparation Methods
None.