Determinação de arsênio e cromo em insumos farmacêuticos contendo enxofre por espectrometria de absorção atômica com forno de grafite e análise direta de amostras sólidas

Abstract

In this work a procedure was developed using direct solid sampling (DSS) and graphite furnace atomic absorption spectrometry (GF AAS). The study was applied to the determination of As in hydrochlorothiazide and barium sulfate and of chromium in barium sulfate using Zeeman effect and continuum source (D2) background correction systems. Results were compared with those obtained using GF AAS, inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP OES) after extraction/digestion of the samples. Results demonstrated that the determination of arsenic in barium sulfate by DSS-GF AAS is possible if the interferences generated by the matrix of the sample are eliminated through the hydrogen introduction in the graphite tube during the pyrolysis step and with the use of palladium as chemical modifier. Arsenic can be only determined in barium sulfate through DSS-GF AAS when the Zeeman effect background correction system was used. Arsenic can be determined in hydrochlorothiazide by DSS-GF AAS using both of the two background correction systems, palladium as chemical modifier and hydrogen introduction in the stage of pyrolysis. Although the intense degradation of graphite platform, Cr determination was feasible in barium sulfate by DSS-GF AAS with the use of the two background correction systems without the use of chemical modifier. Results obtained for arsenic in barium sulfate and hydrochlorothiazide by DSS-GF AAS are in agreement with those from GF AAS and ICP-MS after extraction/digestion of the samples, whereas the results obtained for chromium determination in barium sulfate for DSS-GF AAS are in agreement with those from ICP OES and GF AAS, after extraction. Among the main advantages of the proposed procedure is the absence of the sample preparation step, whereas for ICP OES and ICP-MS this step is normally essential. In addition, it was possible to carry out the calibration by using aqueous reference solutions without the use of certified reference materials for this purpose.