Critical evaluation of sample preparation for SP-ICP-MS determination of selenium nanoparticles in microorganisms – focus on yeast

Abstract

The interest in biogenic SeNPs, produced accidentally or intentionally by a variety of procedures involving microorganisms or plants and their extracts, creates a need for methods for their reliable quantification in complex biological matrices. Particular interest is focused on sample preparation with its potential risks of non-quantitative recoveries as well as possible dissolution or formation of SeNPs during the analytical protocol. This relatively new topic is attracting a lot of attention from academia as well as the food and feed industry, considering aspects of industrial processing and profitability, medical use, and potential toxicity of SeNPs. Ten approaches, including enzymatic, mechanical and chemical extractions, aiming at the extraction of SeNPs from selenized yeast S. cerevisiae were compared. The efficiency of the extraction procedures was evaluated by single particle (SP) – ICP-MS using a collision/reaction cell. An enzymatic digestion resulted in the highest recoveries of SeNPs but, at the same time, the broadest size distribution. Chemical extractions, although leading to recoveries higher than those by mechanical procedures, were not considered as efficient, as they caused partial dissolution of NPs.