DETERMINATION OF N-METHYLCARBAMATE PESTICIDES IN ENVIRONMENTAL WATER SAMPLES USING AUTOMATED ONLINE TRACE ENRICHMENT WITH EXCHANGEABLE CARTRIDGES AND HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY
M. Hiemstra et A. Dekok, DETERMINATION OF N-METHYLCARBAMATE PESTICIDES IN ENVIRONMENTAL WATER SAMPLES USING AUTOMATED ONLINE TRACE ENRICHMENT WITH EXCHANGEABLE CARTRIDGES AND HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY, Journal of chromatography, 667(1-2), 1994, pp. 155-166
A fully automated high-performance liquid chromatographic (HPLC) metho
d was developed for the determination of N-methylcarbamate pesticides
and their polar metabolites in various types of water. Two different,
commercially available, automated trace enrichment devices (OSP-2 and
Prospekt) were investigated as to their performance. Low-carbon C-18-b
onded silica (C-18/OH, 40 mu m particle size) was used, as a selective
sorbent for solid-phase extraction and preconcentration of N-methylca
rbamate pesticides from environmental water samples. PLRP-S (15-25 mu
m), a styrene-divinylbenzene polymeric phase, was also evaluated as an
alternative to extract N-methylcarbamates. After preconcentrating the
N-methylcarbamates on an exchangeable cartridge, the analytes were el
uted with the mobile phase gradient and transferred to the reversed-ph
ase HPLC system. Detection was performed via post-column hydrolysis on
a solid-phase catalyst (anion exchanger), derivatization of the methy
lamine formed with o-phthalaldehyde reagent, and fluorescence detectio
n of the isoindole derivative. Both trace enrichment systems showed go
od quantitative results for the determination of N-methylcarbamates an
d their metabolites at the 0.1 mu g/l level. The repeatability was exc
ellent with relative standard deviations in the range 2-10%. The metho
d detection limits for surface water were between 30 and 50 ng/l. Samp
le throughput is about 30 samples per 24 h, unattended. The method pro
ved to be suitable for monitoring N-methylcarbamate pesticides in envi
ronmental water samples.