矿泉水中的砷（III）

概要

Arsenic is ubiquitous in the earth’s crust in low concentrations. Elevated levels can be found in mineral deposits and ores. Arsenic from such deposits leaches into the groundwater in the form of arsenite (AsO₃^3-) and arsenate (AsO₄^3-), causing its contamination. As(III) is more toxic than As(V) and shows higher mobility in the environment. The selective determination of this species is possible using the method described in this document.

With a limit of detection (LOD) of 0.3 μg/L, anodic stripping voltammetry allows speciation, i.e. the specific determination of As(III). While atomic absorption spectroscopy (AAS) (and competing methods) can only determine the total element concentration, anodic stripping voltammetry is selective to the As(III) oxidation state. The determination is carried out on the scTRACE Gold electrode.

Configuration

用于多模式电极 (MME) 的 884 Professional VA manual

2.884.0110

用于多模式电极 (MME) 的 884 Professional VA manual 是借助多模式电极 pro 或 scTRACE Gold 或铋液滴电极使用伏安法和极谱法进行痕量分析的入门仪器。此项已经证实的瑞士万通电极技术与恒电位/恒电位仪以及外接的灵活 viva 软件联用，在重金属测定领域中展现了新的前景。带有经认证的校准器的恒电位仪在每次测量之前均自动冲洗进行校准，确保可能的高精度。通过此仪器也可使用旋转圆盘电极进行测定，例如借助«循环伏安溶出法»（CVS）、«循环脉冲伏安溶出法»（CPVS）和计时电位法（CP）测定电镀池中的有机添加剂。借助可更换的测量头，可在使用不同电极的各种应用之间实现快速切换。使用 viva 软件进行控制、数据采集和评估。用于 MME（多模式电极）的 884 Professional VA manual 供货时配备大量附件，包括用于多模式电极 pro 的测量头。电极组和 viva 许可证则须单独订购。

VA 电极装备，配备 scTRACE Gold，用于 Professional VA 仪器

6.5339.050

整套电极组，用于测定砷或汞。包括用于 scTRACE Gold、scTRACE Gold、搅拌器和量杯的支架。

946 Portable VA Analyzer (scTRACE Gold)

2.946.0010

用于测定重金属，如痕量砷，汞，铜，铅，锌，镍，钴，铁、铋或锑之类重金属的便携式金属分析器。scTRACE Gold 适用的仪器版本。该系统由恒电位仪和集成了搅拌器与可更换式电极的独立测量台构成。该设备用 Portable VA Analyzer 软件驱动。电源由 USB 接口和内置的可充电电池提供。设备装在手提箱内交付，包含所有必需的附件。

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Sample

Bottled mineral water

Experimental

Figure 1. 946 Portable VA Analyzer (scTRACE Gold version)

The scTRACE Gold is electrochemically activated prior to the first determination. In the next step, the water sample and the supporting electrolyte are pipetted into the measuring vessel. The determination of arsenic is carried out with the 884 Professional VA or with the 946 Portable VA Analyzer using the parameters specified in Table 1. The concentration is determined by two additions of an arsenic standard addition solution.

Figure 2. 884 Professional VA fully automated for VA

**Table 1.** Parameters
Parameter	Setting
Mode	SQW – Square wave
Deposition potential	-0.5 V
Deposition time	60 s
Start potential	-0.3 V
End potential	0.4 V
Peak potential As	0V

Electrodes

scTRACE Gold

Results

With a 60 s deposition time, this method is suitable for the determination of arsenic in water samples in concentrations from β(As(III)) = 0.3–10 μg/L.

Figure 3. Determination of arsenic in bottled mineral water (946 Portable VA Analyzer; 60 s deposition time)

**Table 2.** Results of the determination of As(III) in mineral water
Sample	As (μg/L)
Bottled mineral water	1.4

References

Application Bulletin 416: Determination of arsenic in water with the scTRACE Gold

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