Study And Application Of Fluorescence Profile For Trace Bromate In Drinking Water

Bromate is a by-product generated in drinking water when ozone was used as disinfector,which is a kind of cancerogen with a 2B class,and the content of bromate would be monitored effectively.Fluorescence analysis is a satisfactory method with variuos advantages such as simple apparatus,rapid detection,high sensitivity and low cost.It is significant to form a fluorescence method for rapid monitoring the’ content of trace bromate in drinking water.In this thesis,several works based on fluorescence quenching of rhodamine reagents,kinetic differentiation between bromate-rhodamine B and chlorite-rhodamine B,and masking reaction of chlorite,have been incomplete and a sensitive profile for trace bromate has been well established.The main contents can be summarized as follow four chapters:In chapter 1,a review on the development of the analysis profiles for trace bromate has been introduced.The progress on fluorescence analysis methods for bromate has been demonstrated in detail,and then the topic and research plan of this thesis are put forward.In chapter 2,based on the oxidation nature of bromate,a sensitive fluorescence method for detecting trace bromate has been gained.By using butyl rhodamine B as a pioneer fluorescent reagent,effects of reaction temperature,reaction time,reagents concentration,and co-existing ions,have been investigated,and then a desirable feasibility of sensitve analysis of bromate was obtained.Furthermore,the quenching efficiency of various fluorescence reagents was evaluated and RhB was selected as the optimal fluorescence indicator for trace analyisi of bromate with a detection limit of 0.14 μg/L.Applied to mineral water fortified samples,the recovery rate of bromate was in the range from 83.3%to 108.3%,which was in a good line with that obtained by ion chromatography.In chapter 3,based on the kinetic differentiation between bromate-rhodamine B and chlorite-rhodamine B,a measurement equation of fluorescence quenching against the concentration of bromate and chlorite was achieved.Effects of reaction temperature and reagent concentration have been investigated,and a rapid and effective method for simultaneous determination of bromate and chlorite was established.A good calibration curve was gained in the range of 2.0-40.0(μg/L for bromate,and 0.5-5.0 μg/L for chlorite.Applied to mineral water fortified samples,the recovery rate was gained in the range from 85.0%to 111.7%for bromate and 83.3%to 116.0%for chlorite,which was in an acceptable line with that obtained with ion chromatography.In chapter 4,to eliminate the interference of high concentration of chlorite on bromate,an efficient masking reagent of chlorite has been studied.In our experiments,nitrite was used to make chlorite ion reduced,and excess nitrite was eliminated with anhydrous sulfanilic acid.A good calibration curve was gained in the range of 2.0-40.0 μg/L for bromate,and the permissible concentration for chlorite was of 700 μg/L.Applied to mineral water fortified samples,the recovery rate was gained in the range from 77.8%to 113.5%without apparent interference from chlorite.The result was in a good line with that obtained with ion chromatography.