Flow analysis-hydride generation-gas phase derivative molecular absorption spectrophotometric determination of antimony in antileishmanial drugs

Abstract

Recebido em 21/2/08; aceito em 25/8/08; publicado na web em 26/1/09In the present work, the development of a method based on the coupling of flow analysis (FA), hydride generation (HG), and derivative molecular absorption spectrophotometry (D-EAM) in gas phase (GP), is described in order to determine total antimony in antileishmanial products. Second derivative order (D 2 224nm ) of the absorption spectrum (190 -300 nm) is utilized as measurement criterion. Each one of the parameters involved in the development of the proposed method was examined and optimized. The utilization of the EAM in GP as detection system in a continuous mode instead of atomic absorption spectrometry represents the great potential of the analytic proposal.Keywords: gaseous phase UV molecular absorption spectrophotometry; antimony; leishmaniasis. introductionThe pharmaceutical literature on antimony mainly deals with the use of organic compounds as chemotherapeutic agents. It has lapsed almost a century from the introduction of organic antimonials into the treatment of leishmaniasis. This parasitic disease is widespread in the world. The World Health Organization (WHO) estimates a worldwide annual incidence of about 12 million and a population of 350 million people at risk of acquiring one of the forms of the disease. 1 Sodium stibogluconate (Pentostam  ) and meglumine antimoniate (Glucantime  ) are the pentavalent antimonial drugs of choice in the treatment of leishmaniasis. In Venezuela, another pentavalent antimonial drug for the treatment of leishmaniasis is also used. This drug called Ulamina is synthesized from antimony pentachloride and N-methyl glucamine (meglumine). 2 Confidence knowledge of the antimony content in the pharmaceutical formulations is very important for prescribing the right dose. Stibiointoxication cases have been reported. 3 Although being old medicines, safety and quality control of these drugs have not been comprehensively evaluated so far. 4,5 Thus, the development of simple, low cost, fast methodologies is important, especially for developing countries. 6 Several analytical methodologies have been developed for the determination of antimony in different aqueous and solid matrices, which have been reviewed by different authors. [7][8][9][10] Formation of volatile SbH 3 (hydride generation, HG) followed by its determination is a common practice in flow-injection atomic spectrometry using absorption (AAS) or emission with inductively coupled plasma (ICP-AES) 11 as the detection technique. A good deal of research on antimony has been, and continues to be, devoted to trace analysis of antimony. 8 However, the hyphenated instrumental techniques used for that purpose are usually sophisticated and expensive.Works on antimony in formulated dosage forms are scanty. In this context, the analytical methods reported by the specialized literature dealing with the determination of antimony in pharmaceutical products are based -mainly-on redox reactions. In this fashion, Bloomfield et al. 12 developed a method using f...