Effect of ultrasonic agitation on the release of copper, iron, manganese and zinc from soil and sediment using the BCR three-stage sequential extraction

An ultrasonic bath and an ultrasonic probe have been used to develop rapid versions of the three-stage Community Bureau of Reference (BCR, now the Sta ndards, Measurement and Testing Programme) sequential extraction procedure. The effect of the ultrasonic treatments on the extraction of copper, iron, manganese and zinc from a sewage sludge-amended soil has been assessed. Re coveries similar to those of conventional shaking (i.e., conventional value , +/- 30%) could generally be obtained for copper, manganese and zinc, but not for the important matrix element iron. With the use of compromise sonic ation conditions, steps 1, 2 and 3 of the sequential extraction (excluding the hydrogen peroxide digestion in step 3, which was not performed with son ication) could be completed in 3, 5 and 1 min, respectively, using the ultr asonic probe, and in 3, 1 and 1 h, respectively, using the bath. The extrac tion procedures developed using the soil performed well when applied to lak e sediment BCR CRM 601. Analyte partitioning was generally similar to that obtained with mechanical shaking, and overall metal recoveries were 84-98% of those obtained with the conventional BCR protocol, except for copper ext racted with the probe (74%). Poorer performance (analyte recoveries, 58-104 %) was obtained when the methods were applied to an intertidal sediment. Th is highlights the difficulty of developing a version of the BCR extraction, with ultrasonic assistance, which gives a performance equivalent to conven tional shaking when applied to different substrates.