NEMI Method Summary

Method Summary Information

Method Number: D5317 Media: WATER
Revision: Current edition approved Dec. 10, 1998. Originally published as D5317-92.
Method Source: ASTM International
Subcategory: ORGANIC Analytes in this method
Official Name: Standard Test Method for Determination of Chlorinated Organic Acid Compounds in Water by Gas Chromatography with an Electron Capture Detector
Descriptive Name Chlorinated Organic Acids in Water
Source Info: ASTM International
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Citation: ASTM Volume 11.02
 
Brief Method
Summary:
 The compounds listed in Section 1.1, in water samples, are converted into sodium salts by adjusting the pH to 12 with sodium hydroxide solution (240 g/L) and shaking for 1 h. Extraneous neutral material is removed by extraction with methylene chloride. The sample is acidified, the acids are extracted with ethyl ether and converted to methyl esters using diazomethane. After the excess reagent is removed the methyl esters are determined by capillary column GC using an electron capture (EC) detector. Other detection systems, such as microcoulometric and electrolytic conductivity, are not as sensitive as EC for measurement of chlorinated acid esters but are more specific and less subject to interferences. A mass spectrometer may also be used as a detector.
This test method provides a magnesium silicate cleanup procedure to aid in the elimination of interferences that may be present.
Scope And
Application:
 This test method covers a gas chromatographic procedure for the quantitative determination of selected chlorinated acids and other acidic herbicides in water. Similar chemicals may also be determined by this test method, but it is the user's responsibility to verify the applicability of this test method to any compounds not listed in this scope.
Applicable
Conc Range:
 From approx 0.5 to 10 except for 2,4-DB which is 8 - 40 ug/L
Interferences: Method interferences may be caused by contaminants in solvents, reagents, glassware, and other sample processing apparatus that lead to discrete artifacts or elevated baselines in gas chromatograms.
The acid forms of the analytes are strong organic acids that react readily with alkaline substances and can be lost during sample preparation. Glassware and glass wool must be acid-rinsed with hydrochloric acid (1 + 9) and the sodium sulfate must be acidified with sulfuric acid prior to use to avoid analyte loses due to adsorption.
Organic acids and phenols, especially chlorinated compounds, cause the most direct interference with the determination. Alkaline hydrolysis and subsequent extraction of the basic sample removes many chlorinated hydrocarbons and phthalate esters that might otherwise interfere with the electron capture analysis.
Interferences by phthalate esters (commonly leached from plastics) can pose a major problem in pesticide analysis when using the ECD.
Carry-over effects are minmized by between-sample of equipment with MTBE.
Matrix interferences may be caused by contaminants that are coextracted from the sample.
QC Requirements: As specified by Practice D 5789, the minimum quality control requirements for the analysis of organic compounds in water are verification of system calibration, verification of control at zero analyte concentration, initial demonstration of proficiency, verification of control at representative analyte concentration, assessment of precision, assessment of bias, and maintenance of interlaboratory traceability. Also, specific to this test method are the determination of surrogate compound recoveries in each sample and blank, monitoring internal standard peak area or height in each sample and blank (when internal standard calibration procedures are being used), and daily assessment of instrument performance.
Sample Handling: Test for the presence of chlorine with potassium iodide-starch test paper previously moistened with dilute acid. Darkening of the test paper indicates the presence of chlorine (and a few other oxidizing materials). Add 80 mg Na2S2O3to the bottle before adding the sample.
After the sample is collected in the bottle containing preservative, seal the bottle and shake vigorously for 1 min. Immediately store the sample at 4oC away from light until extraction.
Max Holding Time:
 Preservation study results indicate that the analytes (measured as total acid) present in samples are stable for 14 days when stored under these conditions (4).
 
Relative Cost: Unknown
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