Determination of asulam by fast stopped-flow chemiluminescence inhibition of luminol/peroxidase

An efficient, sensitive and fast stopped-flow method has been developed to determine asulam in water, based on its inhibition effect on the horseradish peroxidase–luminol–hydrogen peroxide chemiluminescence reaction, (HRP–luminol–H2O2). Ultra fast data acquisition (0.20 s) facilitates excellent selectivity because no interferences from concomitants in the matrix act in such short time scale. The precision as repeatability (expressed as relative standard deviation, n = 10) was 0.4% at a 40 pM level. The detection limit was 1.5 pM (0.35 ng/L) and 7.15 pM in pure and raw water, respectively. The calibration data over the range 5–60 pM present a correlation coefficient of r = 0.9993. The proposed method has been applied to determine asulam in water samples by using solid-phase extraction (SPE). Mean recovery value was 98.1 ± 2% at 50 pM level.