Determination of vanadium, molybdenum and chromium in soils, sediments and sludges by electrothermal atomic absorption spectrometry with slurry sample introduction

Abstract

Procedures for determining vanadium, molybdenum and chromium in soil, sediment and sludge samples were developed. The samples were prepared as slurries and fast programme methodology was used. Suspensions were prepared by weighing 10–250 mg of sample and adding 25 ml of a solution containing 2.5% and 50% v/v of concentrated hydrofluoric acid for vanadium and molybdenum determination, respectively. Suspensions prepared in 2.5% v/v of concentrated hydrofluoric acid were diluted for chromium analysis before being directly introduced into the furnace. Prior mild heating in a microwave oven is recommended. No modifier other than hydrofluoric acid was required and calibration was carried out using aqueous standards. The characteristic masses were 31, 9 and 5.8 pg for vanadium, molybdenum and chromium, respectively, and the corresponding detection limits were 70, 22 and 11 pg. The reliability of the procedure was checked by comparing the results obtained with others based on microwave-oven sample digestion and by analyzing various certified reference materials.