Appraisal of different electrothermal atomic absorption spectrometric methods for the determination of strontium in biological samples

Abstract

A comparative study of various potential chemical modifiers (La, Mg, Pd, Ni, Ta, Lu, Sm, Eu, Ho, Er, Tm and Tb) as well as of different background correction procedures (deuterium and Zeeman effect) and atomization techniques (wall and platform) for the direct determination of strontium in biological samples was carried out. Two instruments, one with deuterium and the other with Zeeman effect background corrections have been used to perform the experiments. Although La, Mg, Pd, Ta and Lu had a positive effect, lanthanum alone provided the best performance for the determination of strontium in whole blood, urine and bone digests using wall atomization without deuterium background correction. However, neither chemical modifier produced any significant improvement in sensitivity when Zeeman effect background correction with integrated platform atomization was used. Under the optimized conditions, the characteristic masses were 0.82 and 2.20 pg and the detection limits (3 σ) were 0.13 and 0.30 μg l −1 with wall atomization and with Zeeman effect background correction respectively. Recovery studies and analysis of standard reference materials certified for strontium were performed to assess the accuracy. The results for the determination of strontium in real samples with wall atomization and lanthanum as chemical modifier, agreed well with those obtained with Zeeman effect background corrector with a precision typically between 0.5 and 3%. Both procedures can be recommended, and the choice will depend on instrument availability.