Method to analyse herbicides in water

Agilent Technologies Europe has announced the availability of a new chromatography method for analysing acidic herbicides in groundwater and potable water.

The new method meets all performance requirements (standard deviation, bias, and total error) set by the United Kingdom's Drinking Water Inspectorate.

The liquid chromatography/mass spectrometry (LC/MS) method uses atmospheric pressure electrospray ionisation, which eliminates the derivatisation step found in previous methods and achieves low levels of detection with only small sample volumes (50µl in validation tests).

Derivatisation involves use of potentially hazardous chemicals and adds time to each analysis. The Prescribed Concentration or Value (PCV) for a single herbicide in drinking water in the UK is set at 0.1µg/l.

The method is capable of detecting to much lower levels: 0.01 to 0.02µg/l in laboratory tests analysing 19 acidic herbicides and one amide herbicide.

The system used for the method included an Agilent 1100 series LC/MS quadrupole coupled to an Agilent 1100 series LC system with quaternary pump, autosampler, thermostated column compartment and vacuum degasser.

A diode array detector (in line ahead of the mass spectrometer) was used as a troubleshooting tool.

The atmospheric pressure electrospray ionisation source was used in negative ion mode.

Standard analytical methods for these herbicides in water matrices involve either liquid-liquid extraction or solid phase extraction (SPE) followed by derivatisation using diazomethane or pentafluorobenzyl bromide and analysis by gas chromatography (GC) or GC/MS.

For further information, request application note 'Determination of acidic herbicides in groundwater and potable water by LC/MSD using selective ion monitoring', Agilent publication number 5988-5882EN.

This note is available without charge from any Agilent sales office or its website.