EPA-OGWDW/TSC: 552.2: Haloacetic Acids and Dalapon in Water Using GCECD
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Official Method Name
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Determination of Haloacetic Acids and Dalapon in Drinking Water by Liquid-Liquid Extraction, Derivitization and Gas Chromatography with Electron Capture Detection |
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Current Revision
| Revision 1.0, 1995 |
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Media
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WATER |
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Instrumentation
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Gas Chromatography with Electron Capture Detection |
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Method Subcategory
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Organic |
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Method Source
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Citation
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Brief Method Summary
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A 40-mL sample is adjusted to a highly acidic pH and extracted with methyl tert-butyl ether (MTBE). The haloacetic acids that have been partitioned into the MTBE phase are then converted to their methyl esters by the addition of acidic methanol followed by slight heating. The acidic extract is neutralized by a back extraction with a saturated solution of sodium bicarbonate. The concentrations of acids in the extract are measured using a capillary column gas chromatography (GC) system equipped with an electron capture detector (ECD). |
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Scope and Application
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This method determines haloacetic acids in drinking water, ground water, raw source water, and water at any intermediate treatment stage. |
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Applicable Concentration Range
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Ranges differ depending on matrix and instrumentation used for detection. |
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Interferences
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(A) Glassware contamination: Thoroughly clean glassware, including baking or solvent rinse. (B) Extracted interferences: Interference from extracted non-target compounds, with retention times similar to target compounds, can be reduced using confirmation analysis. (C) Memory Interferences: Carryover may occur whenever high and low concentration samples are analyzed in sequence. Rinse the sample syringe and associated equipment with MTBE between samples. Also, unusually concentrated samples should be followed by one or more injections of MTBE to ensure accurate values for the next sample. (D)Bromochloroacetic acid coelutes with an interferant (probably dimethyl sulfide) on the DB-1701 confirmation column. Quantitative confirmation can be performed by manual integration that includes only the peak area of the target ester. (E) Methylation using acidic methanol results in a partial decarboxylation of tribromoacetic acid. Therefore, a substantial peak for bromoform will be observed in the chromatograms. Its elution does not interfere with other analytes. |
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Quality Control Requirements
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Laboratory performance check standard, initial demonstration of laboratory capability, method detection limit (MDL) determination, analysis of laboratory reagent blanks (LRBs), continuing calibration check standard, laboratory fortified sample matrices, field duplicates, and monitoring surrogate and/or internal standard peak response in each sample and blank. Additional QC practices may be added. |
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Sample Handling
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Grab samples must be collected in accordance with conventional sampling practices using amber glass containers with TFE-lined screw-caps and capacities in excess of 50 mL. Dechlorinate with crystalline or granular ammonium chloride (NH4Cl) to produce a concentration of 100 mg/L in the sample. After sample is collected, seal the bottle and swirl until the ammonium chloride is dissolved. Store samples at 4oC away from light until analysis. |
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Maximum Holding Time
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14 days; extracts within 7 days if stored at 4oC or 14 days if stored at -10oC or less. |
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Relative Cost
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$201 to $400 |
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Sample Preparation Methods
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