Infrared radiation applied as a heating source in milk sample preparation for the determination of trace elements by inductively coupled plasma-optical emission spectroscopy

Abstract

The use of infrared (IR) radiation as a heating source for milk sample preparation in trace element analysis by inductively coupled plasma optical emission spectroscopy (ICP-OES) was investigated. Three strategies were studied: 1) a system that combined IR and microwave radiation (IR-MW); 2) partial digestion using only IR radiation (IR); and 3) partial digestion using IR radiation and vanadium pentoxide as a catalyst (IR-V2O5). Accuracy varied according to the element determined. The procedure using only IR radiation presented 15.1 ± 0.3 mg g-1 for Ca, 0.76 ± 0.03 µg g-1 for Cu, 217 ± 2 µg g-1 for Fe, 14.8 ± 0.7 mg g-1 for K, 1.17 ± 0.03 mg g-1 for Mg, 4.41 ± 0.08 mg g-1 for Na, 16.2 ± 0.1 mg g-1 for P and 30.5 ± 0.6 µg g-1 for Zn in non-fat milk. The use of IR radiation for sample preparation in trace element analysis is an easy to implement and a low-cost alternative for laboratories of food analysis that do not have a microwave available.