Determination Of Bromate In Drinking Water By Capillary Electrophoresis With Electrochemical Detection

Bromate was decided as 2B-class potential carcinogen by IARC (International Agency for Research on Cancer), it is a main by-product after using ozone for disinfection of drinking water when bromide exists in the water. Due to the popularity of ozonization in the water market, establishing a rapid, convenient and low-cost detection method for bromate is meaningful for quality-monitoring in the drinking water company.HPLC, Ion Chromatography, Capillary Electrophoresis (CE, with UV detection) and electrochemical method (ED) is presently used to detect the bromate in drinking water, however there are not reports about the bromate determination by CE-ED method, Which is a high-sensitivity method and it has the advantage of good-selectivity, low-instrument-cost and easy-popularization. Therefore, the CE-ED method has been widely employed in the field of analytical chemistry. Because of their particular properties after surface bonding of certain material, chemically modified electrodes can increase the sensitivity of determinant by enrichment. The main contents are as follows:A MWNTs/PPy/PMo12 modified pencil graphite electrode (PGE) has been developed. The capillary electrophoresis with electrochemical detection (CE-ED) method has been employed for detecting the bromate (BrO3-) without the interference of chlorate (ClO3-) and iodate (IO3-) in drinking water with the electrode:PGE/MWNTs/PPy/PMo12.The effects of several factors on CE-ED were investigated. Under the optimum conditions, the bromate could be well separated in the capillary at the working potential of -0.24V, separation voltage of-15kV, injection time for 6s at -15kV in a phosphate running buffer (KH2PO4-H3PO4, 50mmol/L, pH=2.2). Under the optimum conditions, The peak area was linear with the concentration of bromate from 1.0×10-6 mol/L to 5.0×10-3mol/L with a detection limit (S/N=3) of 4.0×10-7mol/L.The RSDs (n=7) of peak area and retention time for the determination of bromate were 1.9% and 1.4%(n=7){PDDA/MWNTs}5/PDDA/PMo12 modified film was assembled by electrostatic adherence of positively charged PDDA and negatively charged MWNTs after acidification onto a PGE. Electrochemical properties of the modified electrode were investigated by CV and SEM method and the results showed that the electrode displayed a good electrocatalytic activity to the reduction of bromate. Lay numbers and the concentration of PMo12 were optimized. The result displayed that the modified electrode had a superior performance, compared with the PGE/MWNTs/PPy/PMo12 electrode, then the {PDDA/MWNTs}5/PDDA/PMo12 modified electrode was applied in CE-AD method. Under the optimum conditions, The peak area was linear with the concentration of bromate from 5.0×10-8 mol/L to 10-4 mol/L with a detection limit (S/N=3) of 2.0×10-8 mol/L. The RSDs (n=7) of peak area and retention time for the determination of bromate (1×10-4 mol/L) were 1.6% and 1.8%(n=7)...