Optimization of selenium detection by hydride generation atomic absorption spectrometry as an option for food analysis

Resumo

Recognized for its role in regulating free radicals and its potential antioxidant activity, selenium (Se) is a crucial trace mineral for the maintenance of the human body homeostasis. Various spectroscopic techniques can be employed for quantifying the element including fluorescence, inductively coupled plasma optical emission spectrometry (ICP OES), and atomic absorption with hydride generation (HG AAS). HG AAS is particularly useful for volatile minerals like selenium, which form hydrides when reacting with reducing solutions. However, it requires precise control of equipment parameters, sample preparation to eliminate interferents, and adjustment of carrier gas flow and reaction solution conditions for accurate quantification. In this context, the study focused in the optimization of the method of quantification of selenium through HG AAS. The parameters of detection were studied with a standard solution of 4.5 μg L-1 selenium, and a 23 full-factorial design with 5 center points was conducted for the concentration of BH4Na (X1: 0.25, 0.50 and 0.75%), the concentration of HCl (X2: 8, 10 and 12%) and the gas flow rate (X3: 50, 100 and 150 mL min-1). Center points showed a mean absorbance of 0.055 ± 0.002, with significant impacts of BH4Na (X1) and gas flow rate (X3) on the spectral signal of the standard solution. Lower BH4Na concentrations (0.25%) and gas flow rates (50 mL min-1) increased signal intensity (gt;0.065). However, differences in HCl concentration did not affect Se absorbance, suggesting that acid solutions ranging from 8% to 12% are acceptable for selenium analysis by atomic absorption spectrometry. The research identified optimal conditions for selenium quantification by HG AAS, aiming to reduce equipment overload and chemical reagent concentrations. These optimized parameters may enhance instrumental sensitivity, allowing for the detection of lower selenium concentrations in food matrices and expanding the analytical range.