Merging Zones FIA System for the Spectrophotometric Determination of Sb(III) and Total Sb in Drugs Used in the Treatment of Leishmaniasis

Abstract

A merging zones flow injection system was developed for the spectrophotometric determination of Sb(III) and Sb(V) in drugs used in the treatment of leishmaniasis. The procedure is based on the selective reaction between Sb(III) and bromopyrogallol red (BPR) with the decrease of the absorbance measured at 555 nm. The concentration of Sb(V) was calculated by difference after determination of total antimony. Influences of chemical and flow parameters such as pH of reaction, BPR concentration, surfactant concentration, carrier and reagent flow rates, loop volume, and coil reactor length were critically evaluated. Selectivity of the method and the suitable conditions for sample preparation before injection were investigated. The obtained results demonstrated that the addition of Triton X‐100 enhanced the sensitivity of the method due to acceleration of the chromogenic reaction. Working on optimized conditions, the detection (3σ) and quantification (10σ) limits were 30 ng mL−1 and 100 ng mL−1, respectively. The RSD observed at 0.25 µg mL−1 was 4.0% and the analytical throughput was 90 hr−1. Three samples of commercial drugs were analyzed according to the developed procedure not presenting any statistical difference in relation to the results obtained by FAAS for total antimony concentration. The authors were invited to contribute this paper to a special issue of the journal entitled “Spectroscopy and Automation”. This special issue was organized by Miguel de la Guardia, Professor of Analytical Chemistry at Valencia University, Spain.