Standard Methods: 6251B: Haloacetic acids and trichlorophenol in Water by Micro Liquid-Liquid Extraction GC Method
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Official Method Name
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Micro Liquid-Liquid Extraction GC Method |
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Current Revision
| Standard Methods Online |
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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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The sample is extracted with MtBE at an acidic pH to extract the nondissociated acidic compounds to be determined. A salting agent is added to increase extraction efficiency. The extracted compounds are methylated with diazomethane solution to produce methyl ester or ether derivatives that can be separated chromatographically. A temperature-progammable GC using a fused silica capillary column and an ECD is used for analysis. |
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Scope and Application
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Haloacetic acids and trichlorophenol |
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Applicable Concentration Range
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0.5 to 30 ug/L for HAAs (1.0 to 30 ug/L for MCAA); 0.25 to 15 ug/L for TCPh. |
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Interferences
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Impurities in extraction solvent and on glassware and other equipment can interfere. |
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Quality Control Requirements
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Include method blanks, an initial demonstration of laboratory capability and detection limits, assessment of the internal standard recovery, determination of surrogate compound recoveries, evaluation of calibration data and curves, sample matrix additions, and precision of replicate sample analysis. |
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Sample Handling
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See Section 6010B.1. Preferably collect grab samples in quadruplicate to allow sufficient volume for replicates and known additions. Flush sampling tap until water temperature stabilizes and stagnant lines are cleared. Collect samples in nominal 40- or 60-mL vials containing approximately 65 mg crystalline NH4Cl (bake overnight at >100oC to eliminate contaminants, which converts free chlorine to a combined chlorine residual, and sealed with TFE-faced septa and screw caps. To minimize aeration, fill vials so that no air bubbles pass through the sample. Do not rinse sample and do not let vial overfill. Seal sample vials with no headspace. |
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Maximum Holding Time
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Hold dechlorinated samples at 4oC, but for no more than 9 d. Sample extracts can be held in a freezer at -11oC for 21 d. |
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Relative Cost
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$201 to $400 |
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Sample Preparation Methods
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