Department of Chemistry, Mokpo National University, Jeonnam 58554, Republic of Korea
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The analytical methods for determination of inorganic arsenics have attracted much attention due to their high toxicity and legislative regulations on food. A new method for the separation and quantitation of As(III) and As(V) was developed by using an ion exchange membrane and laser-induced breakdown spectroscopy (LIBS). Using the anion exchange polymer membrane, As(V) was selectively collected on the membrane, and As(III) was filtered through the membrane. The separated As(V) on the membrane was directly determined by LIBS. The As(III) in the filtrate was then oxidized to As(V) and collected by the membrane for LIBS analysis. The detection limit of As(V) was estimated to be 10 mg/kg. The recovery efficiency for a standard arsenic species was in the range of 97–99%. This method was applied to As-spiked water certified reference materials, and the results showed that the recovery for As(V) was 98.9%. This new speciation method is cost effective, simple and not labor intensive for the quantitation of inorganic arsenic.
The qualitative and quantitative determination of the total arsenic as well as the arsenic species in rice has been very important because rice is one of the main sources of human arsenic intake. However, the extraction and determination of arsenic species in rice has been very difficult because of the severe matrix interference. A new and improved analytical method was developed for the determination of arsenic species in rice by inductively coupled plasma - mass spectrometry (ICP-MS) coupled with ion chromatography (IC). Two internal standards were used. The first internal standard was injected before sample introduction to correct the signal change with time, and the second internal standard was spiked into the sample to reduce the matrix interferences. Recoveries of DMA, MMA, and inorganic arsenic for the certified values (NIST SRM 1568b rice flour) were 116 %, 107 % and 92 %, respectively, with the developed method.