Method 547

Determination of Glyphosate in Drinking Water by Direct-Aqueous-Injection HPLC, Post-Column Derivatization, and Fluorescence Detection

This method is for the determination of glyphosate (N-phosphonomethyl glycine) in drinking water using HPLC with post-column derivatization and fluorescence detection.   A water sample is filtered and a 200 µL aliquot injected into a cation exchange HPLC column.  The analyte is oxidized with calcium hypochlorite after elution from the analytical column. The product (glycine) is then coupled with o-phthalaldehyde-2-mercaptoethanol complex at 38°C to give a fluorophor, which is detected by a fluorometer with excitation at 340 nm and detection of emission measured at >455 nm .

Glyphosate rapidly decomposes in chlorinated waters so it is unlikely that the analyte will be found in tap water except as separate glycine and N-phosphono methyl moieties, neither of which is applicable to this method.

(EPA: Office of Water)


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Method Data

Hold Times, Preservatives, Preps, Collection, Analytical & Documentation
Holding Time:   2 weeks from sample collection to analysis. A preservation study has demonstrated the stability of glyphosate in frozen samples for up to 18 months.
Preservatives:   Samples should be stored at 4°C away from light. Chlorine is destroyed by adding 100 mg/L of sodium thiosulfate to the sample.
Required Preps:   Grab sample bottle: 60 mL screw cap bottles.
Collection Method:   Grab sampling
Analytical Methodology:   HPLC with fluorescence detection
Documentation:   547

Analyte List*

Analyte Formula CAS Number Detection Limit

* The analytes and detection limits listed for each method represent the typical detection limits and analytes reported for that particular method. Keep in mind that analyte lists may vary from laboratory to laboratory. Detection limits may also vary from lab to lab and are dependent upon the sample size, matrix, and any interferences that may be present in the sample.