The Study On Determination Of Trace Mn Ion In Water Environment And Cu,Pb And Zn Ions In Food By 2-mercaptobenzothiazole Coprecipitation-flame Atomic Absorption Spectrometry

With the progress of science and technology and the improvement of people’s living standards,the development of high technology and industry is getting faster and faster,people not only enjoy a lot of convenience,but also suffer from a series of pollution and harm.Heavy metals with the characteristics of great damage,easy to accumulate and so on are particularly serious for the pollution of environment and food that people rely on for survival.Under such a severe situation,higher requirements have been put forward for chemical analysis.Flame atomic absorption spectrometry has been widely used in the determination of heavy metal elements due to its advantages of simple operation,accurate determination and high sensitivity.However,the detection limit is not low enough and it can’t meet the requirements when determining the trace metal content.Therefore,an effective method of separation and enrichment is needed to pretreat the sample in order to meet the requirements of determination.Coprecipitation method is adopted in this paper.Coprecipitation method has been favored by researchers because of simple and rapid operation and high enrichment multiple.This paper adopted cost-effective2-mercaptobenzothiazole（MBT）as coprecipitant innovatively,Fe（III）and Co（II）were used as carrier ion to separate and enrich manganese in the water environment and copper,lead and zinc in food,and the quantitative analysis of the above four trace heavy metals by coprecipitation combined with flame atomic absorption spectrometry.The experiments were performed to optimize the coprecipitation conditions of the system from the selection and dosage of carrier ions,the amount of coprecipitant,pH,coprecipitation time,centrifugal time,sample volume and the influence of coexisting ions,and further explored the sensitivity,precision and detection limit of the method.In addition,this paper also studied the mechanism of coprecipitation in each system,which has a good reference value for the study on mechanism of other separation and enrichment methods.This paper focused on the following four coprecipitation systems:1.Fe（Ⅲ）-MBT coprecipitation system was used to detect Mn in water samples.The sensitivity of the method was 1.27（mg/L）^-1,the precision was 0.86%,and the detection limit was 0.36μg/L.2.Co（Ⅱ）-MBT coprecipitation system was used to detect Cu in celery.The sensitivity of the method was 0.48（mg/L）^-1,the precision was 0.89%,and the detection limit was 0.64μg/L.3.Fe（Ⅲ）-MBT coprecipitation system was used to detect Pb in laver.The sensitivity of the method was 0.09（mg/L）^-1,the precision was 1.29%,and the detection limit was 2.13μg/L.4.Co（Ⅱ）-MBT coprecipitation system was used to detect Zn in rice.The sensitivity of the method was 1.71（mg/L）^-1,the precision was 0.07%,and the detection limit was 0.18μg/L.