Simultaneous rapid determination of halogens in clay using pyrohydrolysis combined with ion chromatography

An ion chromatography (IC) method for rapid determination of halogens (F, Cl, Br and I) simultaneously in clay with pyrohydrolysis as sample digestion was developed. The parameters that significantly affect pyrohydrolysis were investigated and the following conditions of pyrohydrolysis were optimized. 2.0 g clay sample and V2O5 were put into the reactor at 1000 °C for 10 min; the mass ratio of clay sample to accelerator V2O5 was 1:1 and air flow rate was 90 mL min-1; 15 mL solution containing 5.4 mM Na2CO3 and 5.1 mM NaHCO3 was used as receiver solution. The detection of analyte by this method following the proposed pyrohydrolysis procedure indicated that F, Cl, Br and I in clay were presented as F−, Cl−, Br− and I− in receiver solution which were well separated by IC. The accuracy of this approach was confirmed by the analysis of four clays spiked with Chinese Soil Reference Materials (SRMs). The limits of detection (LOD) were 0.030, 0.043, 0.09 and 0.13 μg g−1 for F, Cl, Br and I, respectively. By using a relatively simple and low cost pyrohydrolysis system, up to five samples can be processed per hour, and then F, Cl, Br and I can be determined in clay and other inorganic samples.