EPA-NERL: 548.1 (by MS):  Endothall in Water Using GCMS

  • Summary
  • Analytes
  • Revision
  • Data and Sites
Official Method Name
Determination of Endothall in Drinking-Water by Ion-Exchange Extraction, Acidic Methanol Methylation, and Gas Chromatography/Mass Spectrometry
Current Revision
Revision 1.0, August 1992
Gas Chromatography with Mass Spectrometry Detection
Method Subcategory
Method Source
  Methods for the Determination of Organic Compounds in Drinking Water - Supplement II (EPA/600/R-92-129)
Brief Method Summary
A 100-mL sample is passed through a liquid/solid extraction (LSE) cartridge containing an intermediate strength, primarily tertiary amine anion exchanger mounted on a vacuum manifold and conditioned with appropriate solvents. Extracted endothall is eluted from the LSE cartridge with acidic methanol. After adding a small volume of methylene chloride as a co-solvent, the dimethyl ester of endothall is formed within 30 minutes with modest heating. After addition of salted reagent water, the ester is partitioned into methylene chloride. The extract volume is reduced with a nitrogen purge. The concentration of endothall in the extract is measured using a megabore capillary column gas chromatography (GC) system equipped with a mass spectrometer detector (MS) or a flame ionization detector (FID).
Scope and Application
This method determines endothall in drinking water sources and finished drinking water.
Applicable Concentration Range
Not specified in method. Range differs depending on matrix and instrumentation.

(A) Glassware contamination: Thoroughly clean glassware, including baking or solvent rinse.

(B) Reagent contamination: Use high purity reagents.

(C) Ion interferences: Ca+2 and Mg+2 and sulfate lower recovery by interfering with the ion exchange process.

(D) Extracted interferences: Interference from extracted non-target compounds, with retention times similar to target compounds, can be reduced by cleaning the extract.

Quality Control Requirements

Initial demonstration of laboratory capability, followed by analysis of laboratory reagent blanks (LRBs), laboratory fortified matrix samples, laboratory fortified blanks (LFBs), and QC check standards. A MDL also must be determined.

Sample Handling

Grab samples must be collected in glass containers following conventional sampling practices without prerinsing the bottle before collection. Composite samples should be collected in refrigerated glass containers. Automatic sampling equipment must be as free as possible of plastic tubing and other potential sources of contamination. Dechlorinate with the addition of 80 mg of sodium thiosulfate per L of sample prior to sample collection. Store samples at 4oC away from light and heat until analysis. Biologically active samples should be acidified to pH 1.5 to 2 with the addition of 1:1 HCl:H20.

Maximum Holding Time

7 days; 14 days for extracts.

Relative Cost
$201 to $400
Sample Preparation Methods