Speciation of As(III) and As(V) in fruit juices by dispersive liquid-liquid microextraction and hydride generation-atomic fluorescence spectrometry.

A sensitive method was developed to speciate and quantify As(III) and As(V) in fruit juices. At pH 3.0, As(III) and ammonium pyrrolidine dithiocarbamate (APDC) formed a complex, which was extracted into CCl4 by dispersive liquid-liquid microextraction (DLLME) and subsequently quantified by hydride generation-atomic fluorescence spectrometry (HG-AFS). After As(V) was reduced by thiosulphate at pH 1.7-1.8, total inorganic arsenic (iAs) was determined following the same protocol and As(V) was calculated from the difference. Interference from methylarsonic acid (MMA) was managed at <10% by controlling the pH of the reduction reaction. This procedure achieved 1.2 μg L(-1) limit of detection (3σ) and 92-102% recovery at 10 μg L(-1), and is applicable to most fruit juices except certain pear juice that may contain considerable MMA.