Six arsenic species certified reference material (CRM) solutions have been developed. The speciat...

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Research on Arsenic Speciation CRMs

Six arsenic species certified reference material (CRM) solutions have been developed. The speciation and purity of arsenic in the CRMs were determined using NMR, HPLC-ICPMS methods. Several accurate methods with different principles were used to determine the concentration of arsenic compounds in this CRM.

Human urine was collected from dwellers of high arsenic underground water area for the CRM matrix. This CRM is designed and prepared mainly for accuracy and coincidence guarantee for results in monitoring quality of public health and environment, especially for arsenic poisoning and arseniasis.

Arsenic (As) is a toxic element and has been recognized as a potential human carcinogen. The six most commonly found As species are: arsenobetaine (AB), arsenocholine (AC), dimethylarsinic acid (DMA), monomethylarsonic acid (MMA), arsenite (As(III)) and arsenate (As(V)). These six arsenic compounds differ widely in their toxicity to humans. Their toxicity rank in the following decreasing order: As(III) > As(V) > MMA > DMA > AC > AB. Consequently, a toxicological evaluation of dietary As intake and environmental exposure should be based on mass fraction of each of the element species. An increasing number of requests for As speciation analysis in environmental, biological and clinical fields stimulate development of a reproducible and reliable method. Obviously, there is also a growing need for As species Certified Reference Materials (CRM) for validation of precision and accuracy of new methods.

The speciation and purity of arsenic in these CRMs were determined using nuclear magnetic resonance (NMR) and high performance liquid chromatography - inductively coupled plasma-mass spectrometry (HPLC-ICPMS) methods. Several accurate methods based on different principles, such as coulomb method, HPLC-ICPMS, inductively coupled plasma-mass spectrometry (ICPMS), inductively coupled plasma- optical emission spectroscopy (ICP-OES) and atomic fluorescence spectrometry (AFS), were used to determine the concentration of arsenic compounds in these CRMs. The traceability of the certified value is ensured by using measurement methods and measuring instruments that meet the requirements of metrology.

Human urine for this certified reference material was collected from dwellers of high arsenic underground water area. Then the fresh urine was mixed in mixing vessel ® packed into glass bottle ® freeze-dry in -35℃ for 44 hours ®60Co radioactive ray destroying bacteria ® preserved in low temperature and dry place. The property values were co-certified by six laboratories using two accurate methods with different principles. The statistic average values were used as certified values.

These certified reference materials are designed and prepared mainly for accuracy and coincidence guarantee for results in monitoring the quality of clinical medicine and environment, especially for arsenic poisoning and arseniasis. They are intended to be used in evaluating the determining accuracy of arsenic speciation in water and body fluid, as well as for calibrating analytical instruments.