Fast arsenic speciation in water by on-site solid phase extraction and high-resolution continuum source graphite furnace atomic absorption spectrometry

A method of high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS), combined with on-site separation/solid phase extraction (SPE) has been developed for the speciation of inorganic As (iAs) in geothermal and drinking water samples. The HR-CS-GFAAS calibration curves were linear up to 200 mu g/L As, but using second order polynomial fitting, accurate calibration could be performed up to 500 mu g/L. It has been demonstrated that sample pH should not be higher than 8 for an accurate speciation of As(V) with a recovery of approximate to 95%. Geothermal water had fairly high salt content (approximate to 2200 mg/L) due to the presence of chlorides and sulfates at mg/L levels. Therefore, a two-fold dilution of these types of samples before SPE is recommended, especially, for total As determinations, when the As concentration is as high as 400 mu g/L For drinking water, sampled from public wells with records of As concentrations higher than the 10 mu g/L in the past, the reduction of As contamination below the WHO's health limit value could be observed. However, the electrical conductivity was close to 2500 mu S/cm, i.e., the guideline limit for drinking water, which was due to their higher chloride content. The proposed fit-for-purpose SPE-HR-CS-GFAAS method could be a candidate for screening drinking water quality. (C) 2017 Elsevier B.V. All rights reserved.