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Glyphosate Analysis

Glyphosate (N-phosphonomethyl glycine) is a non-selective, post-emergence herbicide used extensively around the world as a weed and vegetation control chemical. It is sold in Australia under a variety of brand names including Roundup, Weedmaster Duo and Zero.

Glyphosate comes in the free acid form and as various salts — isopropylamine, trimesium, diphenylamine and mono-ammonium glyphosate. The principal degradation product of glyphosate is aminomethylphosphonic acid (AMPA). Glufosinate (DL-phosphinothricin) is a herbicide with a similar structure to glyphosate and belongs to the same chemical class.

AMPAAMPA
glufosinateGlufosinate
glyphosateGlyphosate
Regulators in Australia and overseas have set human health-based limits and environmental guidelines for glyphosate:
  • Australian Drinking Water Guidelines state a guideline value of 1 mg/L for glyphosate in drinking water
  • Australian Pesticides and Veterinary Medicines Authority defines glyphosate as the sum of glyphosate and AMPA

NMI recommends that AMPA be analysed and reported in conjunction with glyphosate for drinking water and environmental samples.

NMI's Capabilities

We have developed a sensitive and highly selective method (NR53) for the determination of glyphosate, AMPA and glufosinate in water (drinking, recycled, ground and catchment), soil and foliage. The method is NATA-accredited.

Herbicide Limit of reporting for water (mg/L) Limit of reporting for soil (mg/kg) Limit of reporting for foliage (mg/kg)
Glyphosate 0.01 0.05 0.5
AMPA 0.01 0.05 0.5
Glufosinate 0.01 0.01 0.5
Chromatographic separation of glyphosate, glufosinate and AMPA using UPLC/MS/MSChromatographic separation of glyphosate,
glufosinate and AMPA using UPLC-MS/MS

Samples are fortified with isotopes of glyphosate and AMPA prior to analysis, treated with fluorenylmethyloxycarbonyl chloride and then analysed by ultra-high performance liquid chromatography mass spectrometry (UPLC-MS/MS). The separation is rapid (see figure) on sub-2 micron particle size columns. Detection is by state-of-the-art MS/MS instrumentation using isotope dilution calibration with isotopically-labelled analogues. 

Validation

We use isotopically-labelled internal standards to ensure a high level of precision for a range of sample types. The method has been validated on typical Australian surface water, drinking water, ground water, soil and foliage.

Sampling and Holding Time

Water samples:

  • 50 mL chilled in polypropylene container
  • chlorinated drinking water samples are required to be pre-treated with sodium thiosulphate
  • holding time 7 days

Solid samples:

  • 50 g chilled in glass or polypropylene container
  • holding time 14 days

For further information please contact customerservice@measurement.gov.au, 1300 722 845 or use our on-line form.