The Development of Arsenic Speciation Reference Material in Ground Water

Arsenic is widely found in nature. Different speciations have different toxicity, for example the toxicity of inorganic arsenic is larger than that of organic arsenic. Therefore, accurate determination of arsenic speciation in water, especially ground water, has important significance for human health and environmental protection. However, there is no arsenic speciation standard reference either nationally or internationally. To this end, five reference materials for arsenic speciation have been developed, which were collected from Shanxi Province and Nei Monggol, typical areas with a high background of arsenic. During collection and preparation of the samples, lyopyilization and protectant were used to ensure stability of the arsenic speciation. The certified content values of total arsenic, As(Ⅲ) and As(Ⅴ) were obtained by Atomic Fluorescence Spectrometry (AFS), Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES), Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and High Performance Liquid Chromatography-Inductively Coupled Plasma-Mass Spectrometry (HPLC-ICPMS). The analytical results indicate that the reference materials were homogeneous and stable. A multi-laboratory collaborative analysis scheme was adopted in the certification procedure. The determination methods were accurate and reliable with reasonable certified values and uncertainties. Moreover, lyopyilization, which is commonly used in the medical profession in order to guarantee the sample stability, was primarily applied to the preparation of the standard reference materials. This series of reference materials fills the gaps at national and international levels.