Agilent Technologies announces improved techniques for analysis of organophosphate and carbamate pesticides and sulfonylurea herbicides using LC/MS detection
Agilent Technologies Europe has announced improved analyses for organophosphates, carbamates and sulfonylureas in environmental samples using liquid chromatography (LC) with mass spectral (MS) detection.
These improvements demonstrate the great versatility of LC/MS techniques in environmental analysis resulting in simplified cleanup, reduced method development time, improved sensitivity, and increased productivity.
Organophosphate pesticides are readily analysed using LC/MS with an electrospray ion (ESI) source.
ESI avoids both the need to derivatise pesticides for increased volatility and the thermal degradation encountered with gas chromatography (GC).
The MS detector identifies each pesticide, even when not completely resolved, and is far more sensitive and specific than a diode-array ultraviolet (UV) detector.
The process is illustrated with a mixture of 16 organophosphate pesticides plus an internal standard.
Carbamate pesticides in foods are usually measured by LC with post-column derivatisation and fluorescence detection.
This non-specific process suffers from false positives, complexity and inadequate sensitivity.
LC with a mass selective detector in selected ion mode provides positive identification of each pesticide with detection limits ranging from 1 to 10ppb for the nine pesticides tested.
These sensitivity levels are achievable in routine analysis because selected ion monitoring reduces the background signal from the food matrix.
Sulfonylurea herbicides are used at very low application rates.
Current EPA methodology requires concentration of the analytes from large samples, a labour-intensive and time-consuming process.
Solid-phase extraction followed by liquid chromatography/ion trap mass spectrometry (LC/ion trap MS/MS), offers a potential 16-fold increase in sample throughput compared to the current EPA method. This automated approach decreases sample size required, reduces extraction and analysis time, and yields a lower limit of quantitation (LOQ) than the current EPA method while still producing acceptable recovery and reproducibility.
For further information, request application notes 'The Analysis of Organophosphate Pesticides by LC/MS', publication number 5988-3774EN; 'Application of Online Solid-Phase Extraction Ion Trap Mass Spectrometry in Environmental Matrices', publication number 5988-3649EN; and 'Routine Analysis of Trace Level Carbamate Pesticides in Food Using an LC/MSD Quad System', publication number 5988-4708EN.
These application notes are available without charge from any Agilent sales office or the website (see above).
