水中砷检测方案(水质重金属)

VA Application Note V-211 Arsenic(IIl) in drinking water byanodic stripping voltammetry atthe 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. As(III) is more toxic than As(V) and shows higher mobility in theenvironment. The selective determination of this species is possible using themethod described in this document. Results As(III) in drinking water 1.4 ug/L Sample●EBottled mineral water ScTRACE Gold 6.1258.000 Measuring solution 15 mL sample +3 mL electrolyte 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 Potential 1 -0.5V 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 Sulfamic acid Sulfamic acid， NH2SO3H，≥ Equilibration time 5s Sweep 99.5%， for analysis， CAS 5329-14-6 Start potential -0.3V Citric acid Citric acid monohydrate， C6H；O7·H2O， for trace analysis*， CAS 5949-29-1 End potential 0.4V Potential step 0.01 V KCI Potassium chloride， for traceanalysis*， CAS 7447-40-7 Frequency 80 Hz Pulse amplitude 0.02V Ultrapure water Ultrapure water， resistivity>18 MOcm (25°C)， type l grade (ASTM D1193) Peak potential As OV As(III) standard stocksolution β(As(III))=1 g/L or equivalent Solutions As(III) standard addition solution β(As(III))=1 mg/L， acidifiedwith 1 mL/L HNO3 inoxygen-free ultrapure water www.metrohm.com QMetrohm 本文利用946便携式 重金属快速分析仪测定了饮用水中的三价砷，给出了相应的实验条件。本方法稳定、简便、快速，适用于三价砷的准确定量。