LONG-TERM MONITORING OF PESTICIDES AND POLAR TRANSFORMATION PRODUCTS IN-GROUND WATER USING AUTOMATED ONLINE TRACE-ENRICHMENT AND LIQUID-CHROMATOGRAPHY WITH DIODE-ARRAY DETECTION
S. Dupas et al., LONG-TERM MONITORING OF PESTICIDES AND POLAR TRANSFORMATION PRODUCTS IN-GROUND WATER USING AUTOMATED ONLINE TRACE-ENRICHMENT AND LIQUID-CHROMATOGRAPHY WITH DIODE-ARRAY DETECTION, International journal of environmental analytical chemistry, 65(1-4), 1996, pp. 53-68
An automated system using on-line trace-enrichment, separation by liqu
id chromatography with a gradient elution and diode array detection is
described for monitoring pesticides in ground water. Two systems were
used for covering the wide range of polarities of the targeted pestic
ides: the first one consisted of a PLRP-S precolumn and a C-18 analyti
cal column for moderately polar to non polar compounds and the second
one, specially designed for the determination of polar pesticides and
degradation products, consisted of a precolumn and analytical column b
oth packed with porous graphitic carbon. The detection limits that can
be reached by the two systems are in the low 0.1 mu g/l for the groun
d water samples of interest with the handling of 100-150 mi of water.
An application is presented with the first objective of monitoring the
quality of a ground water reservoir which comes from a small basin wh
ere the amount and nature of pesticides applied are known and where at
razine has been banned for the last five years and replaced by terbuty
lazine. The second objective was to have a better knowledge of the beh
aviour and persistence of pesticides from the results of a long-term s
urvey of 18 months. Obviously, the water solubility is an important pa
rameter for the leachability of pesticides. Although banned on this si
te for the last five years, atrazine and deethylatrazine are found at
constant concentrations, 0.5 and 0.7 mu g/l respectively all the year
round. The on-line system with the PGC precolumn and analytical column
allowed to confirm the deethylatrazine concentration as well as the v
ery low concentration (< 0.05 mu g/l) of both hydroxyatrazine and deis
opropylatrazine. Although applied in replacement of atrazine, neither
terbutylazine nor its major dealkylated metabolite were detected until
now. Other more soluble compounds such as isoproturon or metamitron a
re detected during the period following their application.