THE STUDY OF NOVEL SIMPLIFIED COLUMN-SWITCHING TECHNOLOGY FOR THE DETERMINATION OF TRACE OF BROMATE IN THE PRESENCE OF HIGH CONCENTRATION MATRICES

摘要

Many techniques have been developed to determine the trace level ions in the presence of high concentration of matrices, in which column-switching ion chromatography technology is the most widely used one. The determination of bromate in drinking water is a distinct example in this area while bromate is a kind of disinfection by-product of drinking water. It can be a potential human carcinogen, even if the concentration is a low μg/L level. In this paper a novel simplified column-switching method for the determination of trace bromate was proposed without any pretreatment. The installation is showed in Fig.1. The switching time window was confirmed by the retention time of determined ions. This technology can completely carry out the same function as the other column-switching technology do, but only one extra ten-way injection valve coupled to ion chromatograph was used. In this paper the high-capacity and hydroxide-selective anion-exchange column IonPac AS19 was selected and the eluent was generated from EG40. The IonPac AG11-HC was selected as an appropriate concentrated column by studying the concentrated efficiency of four guard columns on the bromate. By using column-switching technology, it should be possible to determine 0.2 μg/L bromate in the presence of 100 mg/L chloride by direct injection of 2000 μL without any pretreatment and the relative standard deviation (RSD) of the peak height for the eleven successive injections of 0.2 μg/L bromate solution is 23.1%. The method detection limit of bromate is 0.09 μg/L, which showed the method was very sensitive. The technology had been applied for the determination of bromate in drinking water, and the spike recovery is in the range of 96-104%. Chromatograms of some brand bottled drinking water sample, drinking water spiked with bromate are reported in Fig. 2. As showed in Fig. 2, both the peak type of bromate and the resolution of bromate and chloride got better by using column-switching.