On-line solid phase extraction-hydride generation atomic fluorescence spectrometric determination of trace arsenic in high purity antimony(III) oxide

The determination of As(III) in high purity Sb2O3 was taken as example to illustrate a high selective solid phase extraction (SPE) with non-polar resins as the sorbent. The extraction was based on the fact that in concentrated HCl solutions, As(III) forming molecular covalent AsCl3 could be attracted by the hydrophobic phase of the resins, whereas the matrix Sb existing only as the ionic Sb-Cl complex could not be adsorbed. The SPE column was made from the Amberlite XAD-16 resin and was on-line coupled with hydride generation atomic fluorescence spectrometer for As(III) detection. Under the optimized conditions, the detection limit (3 sigma) of 0.26 mu g g(-1), the RSD (n = 6) of 6.2% for 50 mg L-1 of As( III) and a linear calibration curve from 2 mg L-1 to 200 mg L-1 with R = 0.9998 were obtained. The recoveries for 10 mg L-1 of As(III) spiked in 1 g L-1 of Sb(III) solution was in the range of 97-102%. The method was applied to the determination of trace As(III) in two highly pure Sb2O3 samples.