REVERSED-PHASE LIQUID-CHROMATOGRAPHIC COLUMN SWITCHING FOR THE TRACE-LEVEL DETERMINATION OF POLAR COMPOUNDS - APPLICATION TO CHLOROALLYL ALCOHOL IN GROUND-WATER

Reversed-phase liquid chromatographic (LC) column-switching employing two C18 columns was used for the trace-level determination of the polar compound chloroallyl alcohol (CAAL), a key metabolite of the soil sterilant dichloroproprene, in ground water. The selectivity of the LC procedure is crucial as CAAL does not possess a chromophoric and must be detected by UV absorbance at 205 nm. It is shown that the selectivity can be enhanced considerably by the use of a column-switching technique. A completely automated procedure was developed for the determination of CAAL with a limit of detection (LOD) of 1 ppb (109) (signal-to-noise ratio = 3). Recoveries at the 20 ppb level were 103% for cis-CAAL [relative standard deviation (R.S.D) = 3.4%] and 102% for trans-CAAL (R.S.D. = 2.5%). Response was linear over more than two decades. The sample throughput is high, as the total time required for the analysis is less than 10 min. If necessary, LODS can be lowered to 0.1 ppb by means of a liquid-liquid extraction combined with concentration step, resulting in recoveries of 88% (R.S.D. = 4.1%) at a level of 2 ppb. Confirmation of CAAL and a second metabolite of dichloropropene, chloroacrylic acid (CAAC), was performed by gas chromatography-negative ionization chemical mass spectrometry (GC-NCI-MS), using derivatization procedures to convert CAAL and CAAC into their pentafluorobenzoyl derivatives, respectively. © 1990.