COLUMN-SWITCHING RPLC FOR THE TRACE-LEVEL DETERMINATION OF ETHYLENETHIOUREA IN AQUEOUS SAMPLES

Column-switching with two C18 separation columns combined with UV detection at 233 nm has been used to determine ETU in ground water samples. The direct assay of ETU (limit of detection, 1 ppb) takes less than 10 min. For the determination of ETU down to a level of 0.1 ppb, preconcentration of ETU is achieved by a liquid-liquid extraction procedure allowing the analysis of at least 12 water samples per day. For both methods (1-ppb and 0.1-ppb level), the overall recovery (96 and 82 %), the repeatability (4.5 and 4.3 %) and the reproducibility (5.0 and 7.9 %) are satisfactory (n = 18 and 28, respectively). More than one hundred samples of ground water were analysed during a 10-month period; over 0.1 ppb of ETU (range, 0.1-300 ppb) was found in 30 % of the samples tested.