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Abstract
A simple and rapid procedure for the determination of manganese in anti‐hypertensive drugs is proposed. The samples were treated with dilute nitric acid (1.2% v/v) with stirring using a vortex stirrer to yield a slurry. To determine the best conditions for analysis by graphite furnace atomic absorption spectrometry (GF AAS), a planning factorial was initially employed that demonstrated that the non‐use of chemical modifiers and the use of lower pyrolysis temperatures were more appropriate. Next, the pyrolysis and atomization temperature curves were obtained. The best pyrolysis and atomization temperatures encountered were 500 and 2200°C, respectively. Calibration was performed by matrix matching. The characteristic mass was 0.70±0.14 pg (the recommended mass was 0.60 pg); the limits of detection and quantification were 0.23 and 0.77 µg l−1, respectively. The precision obtained in the intra‐ and inter‐assay studies of the drug spiked with 0.5, 1.0 and 1.5 µg l−1 of Mn did not exceed 11% (n=7). Recovery studies of the drug spiked with three levels (n=7) of Mn yielded results between 101.0±4.5 and 116.3±9.7%. The results of an analysis of a certified urine sample (two levels of Mn) agreed at a 95% level of confidence. Forty‐eight antihypertensive drug samples were analyzed, and the results varied from 2.9 ng to 1.9 µg of Mn per capsule−1.
Acknowledgments
The authors wish to thank the Conselho Nacional de Pesquisa e Desenvolvimento Tecnológico (CNPq), the Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG) and the Laboratório de Toxicologia Ocupacional da Faculdade de Farmácia (LATO/FAFAR/UFMG). P. C. P. Lara, C. C. Nascentes and J. B. B. Silva received graduate scholarships from the CNPq
