Determination of selenium in cow's milk powder by ICP-MS using a green and efficient extraction induced by emulsion breaking (EIEB) method

Abstract

A sample pretreatment method based on extraction induced by emulsion breaking (EIEB) was developed for the determination of selenium in milk powder by inductively coupled plasma mass spectrometry (ICP-MS). Validation with a certified reference material confirmed the method's excellent accuracy (recoveries: 82.90-97.80 %), good precision (relative standard deviation, RSD = 1.68 %, n = 6), and favorable robustness (RSD = 22.03 %, n = 6). The limit of detection (LOD) was 2.2 μg/kg. Compared to microwave-assisted acid digestion, the EIEB approach reduced acid consumption by 80 % (1 mL vs. 5 mL), simplified the workflow, and eliminated the need for specialized equipment, while maintaining comparable analytical performance. Additionally, Triton X-100 was found to enhance selenium signal intensity, acting as a sensitizer in ICP-MS. Analysis of commercial milk powder samples showed selenium concentrations consistent with nutritional reference values. Overall, the EIEB-ICP-MS method provides a robust and sustainable alternative for selenium quantification in dairy products. Aligned with the principles of green analytical chemistry, it also holds promise for application in the analysis of other hydrophilic food matrices.

Keywords: EIEB; Green analytical chemistry; ICP-MS; Milk powder; Selenium.