DETERMINATION OF ARSENIC IN COMMERCIAL IRON(III) OXIDE PIGMENTS BY ELECTROTHERMAL ATOMIC-ABSORPTION SPECTROMETRY WITH SLURRY SAMPLE INTRODUCTION

A rapid method for the determination of arsenic in iron(III) oxide pigments is described. The sample is suspended in water containing 0.1% m/v Triton X-100 and 0.1% m/v nickel and the slurry is injected directly into the electrothermal atomiser using stabilised temperature platform furnace conditions. Concentrations of iron oxide of up to 1% m/v can be used. The limit of detection is 0.2 μg g-1 of arsenic, which can be reduced to 0.05 μg g-1 using a pre-concentration procedure. Results obtained by direct calibration with aqueous standards agree with those obtained using the hydride generation technique.