Determination of Different Selenium Species in Selenium-Enriched Polysaccharide by HPLC-ICP-MS

To ensure reasonable intake of selenium for humans and provide insights on the development and nutritional analysis of high-quality selenium-enriched food, we established a reliable and highly sensitive method for the determination of selenium species in Z0206 selenium-enriched polysaccharide (Se-EPS). By optimizing the pre-treatment conditions (different enzymes, enzyme combinations, enzymatic time, concentration of enzymes, and centrifugation time), we found that Se-EPS can be effectively hydrolyzed by proteinase K for 18 h, followed by HPLC-ICP-MS determination. The developed method presented high sensitivity with the limit of detection and quantitation in the range of 0.44-2.35 mu g L-1 and 1.54-7.21 mu g L-1. The relative standard deviation (RSD) was all less than 10% and recovery was greater than 80% except for SeCys2, which further validated the repeatability and accuracy of the proposed method. Under the optimized conditions, we could determine 4 selenium species: elemental selenium (78.37%), seleno-methionine (14.27%), selenocystine (0.03%), and Se-methylselenocysteine (5.22%) in Se-EPS. This work provides new insights into the determination of different selenium species in selenium-enriched food.