EPA-ORD / EPA-OST: 538: Organic contaminants in drinking water by direct aqueous injection-liquid chromatography/tandem mass spectrometry
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Official Method Name
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Determination of Selected Organic Contaminants in Drinking Water by Direct Aqueous Injection-Liquid Chromatography/Tandem Mass Spectrometry (DAI-LC/MS/MS) |
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Current Revision
| Version 1.0 |
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Media
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WATER |
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Instrumentation
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Liquid Chromatography-Mass Spectrometery (also High Performance LC-MS; HPLC-MS) |
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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 water sample is collected in a bottle containing sodium omadine and ammonium acetate. An aliquot of the sample is placed in an autosampler vial and the internal standards are added. A 50-µL or larger injection is made into an LC equipped with a C18 column that is interfaced to an MS/MS operated in the electrospray ionization (ESI) mode. The analytes are separated and identified by comparing the acquired mass spectra and retention times to reference spectra and retention times for calibration standards acquired under identical LC/MS/MS conditions. The concentration of each analyte is determined by internal standard calibration using procedural standards. |
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Scope and Application
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This is a direct aqueous injection-liquid chromatography/tandem mass spectrometry (DAI-LC/MS/MS) method for the determination of selected nonvolatile chemical contaminants in drinking water. The following analytes that this method may be used to determine are: Acephate, Aldicarb, Aldicarb sulfoxide, Dicrotophos, Diisopropyl methylphosphonate (DIMP), Fenamiphos sulfone, Fenamiphos sulfoxide, Methamidophos, Oxydemeton-methyl, Quinoline, and Thiofanox |
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Applicable Concentration Range
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Interferences
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1. All glassware must be meticulously cleaned. 2. Method interferences may be caused by contaminants in solvents, reagents (including reagent water), sample bottles and caps, and other laboratory supplies or hardware that lead to discrete artifacts and/or elevated baselines in the chromatograms. 3. Matrix interferences may be caused by contaminants in the sample. 4. Relatively large quantities of the preservatives (Sect. 8.1.2) are added to sample bottles. |
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Quality Control Requirements
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Detailed quality-control requirements are outlined in the method document, which include initial demonstration of capability, and ongoing QC requirements. |
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Sample Handling
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Samples must be chilled during shipment and must not exceed 10oC during the first 48 hours after collection. Samples stored in the lab must be held at or below 6oC until analysis, but should not be frozen. lab must be held at or below 6oC and protected from light until analysis. Samples should not be frozen. |
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Maximum Holding Time
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Must be analyzed within 14 days of collection |
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Relative Cost
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$201 to $400 |
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Sample Preparation Methods
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Collect in amber glass bottles with PTFE-lined screw caps. Add Ammonium acetate and sodium omadine. |
