Direct Zinc Determination in Brazilian Sugar Cane Spirit by Solid-Phase Extraction Using Moringa oleifera Husks in a Flow System with Detection by FAAS

摘要

This paper reports a method for the determination of zinc in Brazilian sugar cane spirit, (cachaça in Portuguese), using solid-phase extraction with a flow injection analysis system and detection by FAAS. The sorbent material used was activated carbon obtained from Moringa oleifera husks. Flow and chemical variables of the proposed system were optimized through multivariate designs. The factors selected were sorbent mass, sample pH, sample flow rate, and eluent concentration. The optimum extraction conditions were obtained using a sample pH of 4.0, a sample flow rate of 6.0 mL min⁻¹, 30.0 mg of sorbent mass, and 1.0 mol L⁻¹ HNO3 as the eluent at a flow rate of 4.0 mL min⁻¹. The limit of detection for zinc was 1.9 μg L⁻¹, and the precision was below 0.82% (20.0 μg L⁻¹, n = 7). The analytical curve was linear from 2 to 50 μg L⁻¹, with a correlation coefficient of 0.9996. The method developed was successfully applied to spiked Brazilian sugar cane spirit, and accuracy was assessed through recovery tests, with results ranging from 83% to 100%.