Speciation of inorganic arsenic in some bottled Slovene mineral waters using HPLC–HGAFS and selective coprecipitation combined with FI-HGAFS

Five bottled mineral waters from the Radenska and the Roga ka springs (Slovenia) were analyzed for their inorganic arsenic species As(III) and As(V) using existing speciation procedures. Both a hyphenated technique (HPLC–HGAFS) and a more conventional technique based on selective coprecipitation of As(III) with dibenzyldithiocarbamate prior to arsenic analysis (FI-HGAFS) were used. The techniques yielded data which were not significantly different on the 5% level, with HPLC–HGAFS to be the least sensitive (DL 1 μg l−1) and the selective coprecipitation technique to be suitable for sub μg l−1 levels (DL 0.05 μg l−1). The latter technique showed recoveries of 96.4±0.4%. In none of the mineral waters As(III) was found whereas the Radenska minerals waters (vrelec Radin, vrelec Miral, Kraljevi Vrelec) contained little As(V) (only detectable with the selective coprecipitation technique) and the Roga ka mineral waters (Tempel, Donat Mg) (very) high As(V) concentrations. Roga ka, Donat Mg even had an average As(V) concentration around the permittable level of 50 μg l−1 for arsenic in minerals waters, viz. 47.8 μg l−1. Speciation calculations based on pH and Eh and taking into account the ionic strength gave a similar speciation pattern then speciation analysis with additional information about the degree of protonation of As(III) and As(V).