F. Hernandez et al., COUPLED-COLUMN LIQUID-CHROMATOGRAPHY APPLIED TO THE TRACE-LEVEL DETERMINATION OF TRIAZINE HERBICIDES AND SOME OF THEIR METABOLITES IN WATERSAMPLES, Analytical chemistry (Washington), 70(15), 1998, pp. 3322-3328
In the present work, a study is reported of the potential of coupled-c
olumn liquid chromatography (LC) applied to the determination of triaz
ine residues in environmental water samples. For this purpose, two dif
ferent techniques have been compared: on-line trace enrichment followe
d by LC (SPE-LC) and coupled-column liquid chromatography (LC-LC). Fir
st, a completely automated liquid chromatographic method based on on-l
ine trace enrichment in a prepacked precolumn and using diode array de
tection has been developed for the simultaneous trace-level determinat
ion of six triazine herbicides (simazine, cyanazine, atrazine, terbume
ton, terbuthylazine, and terbutryn) and the main atrazine metabolites
(desisopropylatrazine, desethylatrazine, and hydroxyatrazine), After p
reconcentration parameters were optimized by testing two different sor
bents (C-18 and PRP-1) in three cartridges with different dimensions,
a sample volume of 100 mL was selected in order to achieve maximal sol
ute preconcentration. Detection limits lower than 0.1 mu g.L-1 were ob
tained even for the most polar analyte (desisopropylatrazine), which p
resented recoveries of around 30%, The method was validated by means o
f recovery experiments in groundwater and surface water samples spiked
with the analytes at different levels (0.2-2 mu g.L-1). Afterward, th
e procedure was successfully applied in a program for monitoring of tr
iazine residues in surface water carried out in a ret area of Castello
n, Spain. Different triazine herbicides such as simazine, terbumeton,
terbuthylazine, and terbutryn were identified and quantified. The iden
tity of these compounds was confirmed by their absorption UV spectra a
nd by GC/MS analysis. Finally, two rapid, sensitive, and selective pro
cedures, previously developed in our laboratory for the trace-level de
termination of triazine compounds, both based on LC-LC, were compared
with the former procedure, The SPE-LC approach showed a considerable i
mprovement in the global sensitivity at the expense of a decrease in s
electivity as well as in sample throughput.