Development and evaluation of an analytical procedure for the determination of antimony in plant materials by hydride generation atomic absorption spectrometry
A procedure for the reliable trace determination of Sb in plant samples based on hydride generation atomic absorption spectrometry (HG-AAS) was developed. Prior to HG-AAS, aliquots (200–400 mg) of dry samples were mineralized with 3 ml of nitric acid, 0.5 ml of sulfuric acid, 0.5 ml of hydrofluoric acid and 0.3 ml of perchloric acid in open digestion vessels made of glassy carbon in a heating block. The accuracy and precision of the developed method was evaluated by the use of six certified plant reference materials. Experimental results for Sb in these reference materials (CRM 281 Rye Grass, BCR, Brussels, Belgium; GBW 07604 Poplar Leaves, GBW 07602 Bush Branches and Leaves and GBW 07605 Tea, Institute of Geophysical and Geochemical Exploration, Langfang, China; and SRM 1515 Apple Leaves and SRM 1575 Pine Needles, NIST, Gaithersburg, MD, USA) agreed well with the certified or indicative values. The detection limit (3ς) in digestion solutions of plant samples was 0.01 µg l–1, the quantification limit of the entire procedure for a reliable determination of Sb was 70 pg Sb g–1 dry powder. The reproducibility of repetitive measurements of digestion solutions was 3.4% at 0.5 µg Sb l–1 and 2.0% at 1 µg Sb l–1. To demonstrate the suitability of the developed method, Sb was determined in leaves of elder bushes (153 ± 5 ng g–1), poplar leaves (75 ± 4 ng g–1) and beech leaves from two different locations (79 ± 3 and 100 ± 3 ng g–1), pine shoots (71 ± 4 ng g–1) and spruce shoots from two sites (141 ± 6 and 29 ± 1 ng g–1). The quantification of Sb from fresh and freeze-dried spruce shoots and beech leaves revealed that the drying process has no distinct influence on the concentration of Sb in the investigated plant materials.