Determination of SeMet and Se(iv) in biofortified yeast by ion-pair reversed phase liquid chromatography-hydride generation-microwave induced nitrogen plasma atomic emission spectrometry (HPLC-HG-MP-AES)

Abstract

Selenium biofortified yeast is the most common dietary Se supplement in human nutrition and in farm animals. Therefore, the production and routine quality control of commercial products are highly demanded. In this work, a simple and cost-effective procedure is proposed for the determination of SeMet and Se(IV) in hydrolyzed yeast, consisting of ion-pair reversed phase separation, post-column hydride generation and Se quantification by atomic emission spectrometry with microwave plasma sustained by nitrogen (HPLC-HG-MP-AES). Freeze-dried biomass was hydrolyzed with methanesulfonic acid; chromatographic separation was performed with a mobile phase containing 0.08% v/v heptafluorobutyric and methanol (92 : 8) at a flow rate of 1 mL min À1 ; the column effluent was on-line mixed with an alkaline solution of potassium persulfate (K 2 S 2 O 8 6% m/v, NaOH 3% m/v), passed through a reaction coil submerged in a water bath at 60 C, and then 10 M hydrochloric acid was added prior to hydride generation in the MP-AES multimode sample introduction system (NaBH 4 2% m/v, NaOH 0.3% m/v). The total chromatographic run was accomplished in 5 min and the evaluated on-column quantification limits were 59 ng Se mL À1 for Se(IV) and 0.52 mg mL À1 for SeMet. The procedure was tested using standardized Seleno Excell® high selenium yeast and then applied for the analysis of Saccharomyces cerevisiae biofortified under different fermentation and exposure conditions. The procedure was capable of detecting differences in selenium concentration among cultures and the results were consistent with those obtained while coupling HPLC separation directly to ICP-MS detection.

Speciation of inorganic selenium in environmental samples after suspended dispersive solid phase microextraction combined with inductively coupled plasma spectrometric determination

“…It can be seen that the LODs obtained by the current method were lower than those reported in the literature [4,5,10,13,[30][31][32]. The LODs was higher than those reported by Chen et al [6].…”

Evaluation of selenium in dietary supplements using elemental speciation

“…When applying the MSA extraction to samples #9 and 10, both labeled as Se-yeast, efficiencies were 5% (iSe) and 75% (SeMet), respectively. This low recovery could either be due to the inability to free the SeMet and/or iSe from the matrix or the presence of Se′ as concluded by (Barrientos et al, 2016). Although not commonly applied to Se-yeast samples, an alkaline extraction, 0.1 M NaOH was applied to two labeled as Se-yeast (#9 & 10).…”

“…Bakirdere et al (2015) reported that water, dilute hydrochloric acid, and enzymatic extractions all achieved comparable extraction efficiencies for non-Se-yeast labeled tablets. Methane sulfonic acid (MSA) has previously been demonstrated to extract SeMet from the selenized yeast reference material SELM-1 (Mester et al, 2006) and other Se-yeast sources (Barrientos, Wrobel, Guzman, Escobosa, & Wrobel, 2016). A basic extraction using sodium hydroxide (NaOH) was applied to selenium-enriched animal feeds with some success (Stadlover, Sager, & Irgolic, 2001).…”

Improvement of selenium enrichment in Rhodotorula glutinis X-20 through combining process optimization and selenium transport

“…The total selenium content in yeast was determined by Hydride Generation Atomic Fluorescence Spectrometry (HG-AFS) [19][20][21]. One millilitre of yeast broth was centrifuged at 8,000 rpm for 10 min and washed 3 times with deionized water to remove selenium ions and selenium salt that were unbound to yeast cells.…”