RAPID-DETERMINATION OF CARBARYL AND 1-NAPHTHOL AT PPT LEVELS IN ENVIRONMENTAL WATER SAMPLES BY AUTOMATED ONLINE SPE-LC-DAD-FD

A fully automated method, based on on-line solid phase extraction (SPE ) then liquid chromatography with diode-array and fluorescence detecti on, has been developed for the trace-level determination of carbaryl a nd 1-naphthol, its primary transformation product, in environmental wa ter samples. By means of rapid enrichment on a 30 mm x 4 mm i.d. 10-mu m ODS pre-column, using a 10-mL water sample, before LC determination both compounds were recovered satisfactorily from different environme ntal water samples spiked at various concentrations (0.05-10 mu g L-1) . Average recoveries were between 93 and 102% with coefficients of var iation between 1 and 4%; detection limits as low as 10 and 50 ng L-1 ( ppt) were estimated for carbaryl and 1-naphthol, respectively. With th is small sample volume, sample throughput was up to 30 samples per day . A carbaryl degradation study was performed by spiking a surface-wate r sample at 2 mu g L-1. After 15 days 80% of the carbaryl was degraded and the presence of 1-naphthol was confirmed by means of its UV spect rum.