AOAC: 991.08: Glyphosate and AMPA in Environmental Water
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Official Method Name
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Glyphosate and Aminomethylphosphonic Acid (AMPA) in Environmental Water by Liquid Chromatographic Method |
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Current Revision
| Final Action - 1993 |
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Media
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WATER |
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Instrumentation
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High Performance Chromatography with Post Column Derivitization and Fluorescence 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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Environmental water containing glyphosate and aminomethylphosphonic acid (AMPA) is evaporated to dryness using a rotary evaporator and the residue is dissolved in EDTA solution. Glyphosate and AMPA are separated and detected by liquid chromatography using a postcolumn reaction specific for primary amines. Glyphosate is oxidized in a postcolumn reactor coil at 50 degrees C with calcium hypochlorite to form glycine. Glycine is reacted with o-phthalaldehyde (OPA) in the presence of mercaptoethanol (MERC) in a second coil to form a fluorophor, which is detected fluorometrically (excitation 340 nm, emission 425-455 nm). AMPA is relatively unreactive toward calcium hypochlorite but undergoes a similar reaction with OPA-MERC reagent to form another fluorophor, which is detected fluorometrically under same conditions as for glycine. |
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Scope and Application
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Applicable to determination of glyphosate and AMPA in ground water, drinking water, and surface water at 0.5-5000 ug/L. |
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Applicable Concentration Range
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0.5 - 5000ug/L |
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Interferences
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Method interferences caused by contaminants in solvents, reagents, glassware, and other sample-processing hardware that lead to discrete artifacts and/or elevated base lines in chromatograms. |
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Quality Control Requirements
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IDMP, MB, SS, CV (every 2 samples) |
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Sample Handling
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Samples should be frozen as soon as possible after collection. |
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Maximum Holding Time
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Relative Cost
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$201 to $400 |
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Sample Preparation Methods
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