PEFTEC - Abstract

Abstract Information :

A commercial arsenic field kit designed to measure iAs in water was modified into a field deployable method (FDM) to measure iAs in rice. The method employs the Gutzeit reaction in which pentavalent arsenic is reduced to arsine. While the method has been validated to give precise and accurate results in the laboratory, its on-site field performance has not been evaluated. A study was designed to test the method on-site in Malawi in order to evaluate its accuracy and precision in determination of iAs by comparing with a validated reference method. Extraction of analytes was performed in the field using a 1% nitric acid extraction. Replicate samples were then analysed in control laboratory conditions using the same procedure and additionally microwave digested and analysed using (high performance liquid chromatography coupled to inductively coupled plasma-mass spectrometer (HPLC- ICP-MS). Statistical tests indicated there were no significant differences between on-site and laboratory iAs measurements determined using the FDM (p=0.263, α=0.05) and between on-site measurements using the FDM and measurements determined using HPLC-ICP-MS under controlled conditions (p=0.299, α=0.05). In reference to HPLC-ICP-MS iAs values, low false positive (<13%) and false negative (<2%) on-site iAs values were observed in reference to the EU maximum limits of iAs in baby rice of 0.1 mg/kg. Both observations indicate high precision and accuracy of the FDM method for iAs in rice. This method allows quick (within 1 hour) and efficient screening of rice containing iAs concentrations that exceed the allowable limits.