Determination of inorganic arsenic in algae using bromine halogenation and on-line nonpolar solid phase extraction followed by hydride generation atomic fluorescence spectrometry

Accurate, stable and fast analysis of toxic inorganic arsenic (iAs) in complicated and arsenosugar-rich algae matrix is always a challenge. Herein, a novel analytical method for iAs in algae was reported, using bromine halogenation and on-line nonpolar solid phase extraction (SPE) followed by hydride generation atomic fluorescence spectrometry (HG-AFS). The separation of iAs from algae was first performed by nonpolar SPE sorbent using Br- for arsenic halogenation. Algae samples were extracted with 1% perchloric acid. Then, 1.5 mL extract was reduced by 1% thiourea, and simultaneously reacted (for 30 min) with 50 mu L of 10% KBr for converting iAs to AsBr3 after adding 3.5 mL of 70% HCl to 5 mL. A polystyrene (PS) resin cartridge was employed to retain arsenicals, which were hydrolyzed, eluted from the PS resin with H2O, and categorized as iAs. The total iAs was quantified by HG-AFS. Under optimum conditions, the spiked recoveries of iAs in real algae samples were in the 82-96% range, and the method achieved a desirable limit of detection of 3 mu g kg(-1). The inter-day relative standard deviations were 4.5% and 4.1% for spiked 100 and 500 mu g kg(-1) respectively, which proved acceptable for this method. For real algae samples analysis, the highest presence of iAs was found in sargassum fitsiforme, followed by kelp, seaweed and laver.