水中总砷检测方案(水质重金属)

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VA Application Note V-210Q.Metrohm Total arsenic in drinking waterby anodic stripping voltammetryat the scTRACE Gold using the946 Portable VA Analyzer Arsenic is ubiquitous in the earth's crust in low concentrations. Elevated levels canbe found in mineral deposits and ores. Arsenic from such deposits leaches intothe groundwater in the form of arsenite (AsO33-) and arsenate (AsO43-)， causingits contamination. In addition to the arsenic originating from natural sources，industry and agriculture contribute to the contamination to a lower extent. TheWorld Health Organization (WHO) recommends a maximum arsenic content indrinking water of 10 ug/L. Results As(total) in drinking water 4.4 pg/L Sample●EBottled mineral water Instrument946 Portable VA Analyzer *e.g. Honeywell Fluka TraceSelect@， Merck suprapur@，or equivalent Solutions Electrolyte c(sulfamic acid)=1 mol/L c(citric acid)=0.5 mol/L c(KCl)=0.45 mol/L KMnO4 solution c(KMnO4)=0.2 mmol/L As(V) standardB(As(V))= 1 mg/L， acidifiedaddition solutionwith 1 mL/L HNO： Analysis Measuring solution 15 mL sample +3 mL electrolyte (+0.1 mL KMnO4 solution) scTRACE Gold 6.1258.000 Parameters Stirrer speed 3000 rpm Mode SQW-Square wave Stirring time 10s Cyclovoltammetric pretreatment Start potential -0.2V Vertex potential 1.0V No. of cycles 5 Potentiostatic pretreatment Potential1 -1V Waiting time 1 60s HNO3 Nitric acid， w(HNO3)=65%，for trace analysis*， CAS 7697-37-2 Potential 2 -0.25V Waiting time 2 5s Equilibration time 5s Sulfamic acid Sulfamic acid， NH2SO3H，≥ 99.5%， for analysis， CAS 5329-14-6 sweep -0.3V Citric acid Citric acid monohydrate， C6HgO7·H2O， for trace analysis*， CAS 5949-29-1 End potential 0.4V Potential step 0.01 V KCI Potassium chloride， for trace analysis*， CAS 7447-40-7 Frequency 80 Hz Pulse amplitude 0.02V KMnO4 Potassium permanganate， for analysis， CAS 7722-64-7 Peak potential As 0V Ultrapure water As(V) standard stocksolution B(As(V))= 1 g/L As(III) and As(V) have a different sensitivity. When bothspecies are present in a sample As(III) has to be oxidizedto As(V) by the addition of KMnO4 solution in order toquarantee correct results for total arsenic. www.metrohm.com 本文利用946便携式 重金属快速分析仪测定了饮用水中的砷，给出了相应的实验条件。本方法稳定、简便、快速，适用于痕量砷的准确定量。