Thin-layer chromatography combined with diode laser thermal vaporization inductively coupled plasma mass spectrometry for the determination of selenomethionine and selenocysteine in algae and yeast

Abstract

In this work we present a simple and cost-effective approach for the determination of selenium species in algae and yeast biomass, based on a combination of thin-layer chromatography (TLC) with diode laser thermal vaporization inductively coupled plasma mass spectrometry (DLTV ICP MS). Extraction of freeze-dried biomass was performed in 4M methanesulphonic acid and the selenium species were vaporized from cellulose TLC plates employing a continuous-wave infrared diode laser with power up to 4 W using a simple laboratory-built apparatus. Selenomethionine and selenocysteine were quantified with limits of detection 3 μg L^-1 in a Se-enriched microalgae Chlorella vulgaris and yeast certified reference material SELM-1. Results delivered by TLC-DLTV ICP MS were consistent with those obtained by a routine coupling of high-performance liquid chromatography (HPLC) to ICP MS. In addition, the TLC approach is capable of analyzing extract containing even undiluted crude hydrolysates that could damage HPLC columns.

Keywords: Chlorella vulgaris algae; Diode laser thermal vaporization (DLTV); Inductively coupled plasma mass spectrometry (ICP MS); Liquid chromatography (LC); Selenium speciation (selenomethionine, selenocysteine); Thin-layer chromatography (TLC).