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饮用水镉铅重金属丝网印刷电极快检系统

AN-V-231

2020-05

zh

Simultaneous determination on Metrohm DropSens Screen-Printed Carbon Electrodes

世界卫生组织（WHO）的《饮用水水质指南》将镉和铅的临时指导值分别设定为 3 µg/L 和 10 µg/L。在经过原位汞膜修饰的瑞士万通 DropSens 丝网印刷电极（SPE）上采用阳极溶出伏安法（ASV）技术，可同时检测出这两种元素低至 0.3 微克/升的浓度。这适用于监测世界卫生组织的指导值。这种方法的主要优势在于其创新性和高性价比的丝网印刷电极

The provisional guideline values in the World Health Organization’s (WHO) «Guidelines for Drinking-water Quality» are set to 3 μg/L for cadmium and 10 μg/L for lead.

The anodic stripping voltammetry (ASV) technique performed on the ex-situ mercury film modified Metrohm DropSens screen-printed electrode (SPE) can be used to simultaneously detect concentrations as low as 0.3 μg/L for both elements. This is suitable to monitor the WHO guideline values.

The main advantage of this method lies in the innovative and cost-effective screen-printed electrode. It is a combined sensor consisting of a carbon working electrode, Ag/AgCl reference, and carbon auxiliary electrode on a ceramic substrate. The disposable sensor does not need maintenance such as mechanical polishing or mechanical cleaning. It can be used conventionally in the laboratory with the 884 Professional VA, or alternatively in the field with the 946 Portable VA Analyzer. This method is best suited for manual systems.

Drinking water, mineral water, sea water

Figure 1. 946 Portable VA Analyzer (SPE)

Prior to the first determination, the ex-situ mercury film is deposited in a separate step on the screenprinted electrode. The water sample and the supporting electrolyte are pipetted into the measuring vessel. The simultaneous determination of cadmium and lead is carried out with the 884 Professional VA or with the 946 Portable VA Analyzer using the parameters specified in Table 1. The concentration of both elements is determined by two additions of a cadmium and lead standard addition solution.

Figure 2. 884 Professional VA, semiautomated system
Table 1. Parameters
Parameter Setting
Mode SQW – Square wave
Deposition potential -1.3 V
Deposition time 60 s
Start potential -1.0 V
End potential -0.4 V
Peak potential Cd -0.72 V
Peak potential Pb -0.52 V
  • Screen-printed carbon electrode (Metrohm DropSens 11L)

With a 30 s deposition time, the limit of detection is around 1 μg/L, and the linear working range is up to 20 μg/L in the measuring solution for both elements.

Figure 3. Determination in mineral water spiked with 2 µg/L cadmium and lead
Table 2. Result
Sample Cd (µg/L) Pb (µg/L)
Mineral water spiked with 2 µg/L Cd and Pb 2.04 1.81
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Internal references: AW VA CH4-0593-042020; AW VA CH4-0594-042020