Speciation of selenium (IV, VI) in urine and serum of thyroid patients by ultrasound-assisted dispersive liquid-liquid microextraction

In-vitro speciation of inorganic selenium (SeIV and SeVI) in serum blood and urine of hyperthyroidism and hypothyroidism patients based on isopropyl ۲-[(isopropoxycarbothiolyl) disulfanyl] ethane thioate (IICDET) as a complexing agent were studied by ultrasoundassisted dispersive liquid-liquid bio-microextraction procedure (USADLLMBE). In first stage, ۱۰۰ μL (≈۰.۱ g) of hydrophobic ionic liquid of [C۸MIM][PF۶] mixed with IICDET ligand and ۱۰۰ μL of acetone. Then, the mixture injected to ۱۰ mL of human samples at pH=۴. After shacking, the Se (IV) ions were complexed by IICDET and extracted to IL at pH=۴ (R-S: …Se). The IL phase was separated from sample by centrifuging and inorganic selenium (Se IV) in remained samples was determined by electro thermal atomic absorption spectrometry (ET-AAS) after back extraction of Se (IV). As speciation, the Se (VI) reduced to Se (IV) in acidic pH (HCl, ۱۳۰OC) and the total Se(TSe) was obtained at pH=۴. Therefore, the Se (VI) was calculated by difference of T-Se and Se (IV). After optimized conditions, the enrichment factor (EF), Linear range and limit of detection (LOD) for inorganic Se (IV) were obtained ۲۰.۱, ۰.۷۵- ۲۰ μg L-۱ and ۰.۱۸ μg L-۱ in serum and urine samples respectively. The results showed us, the concentration of selenium was decreased in thyroid patients as compared to healthy peoples. The validation of methodology was achieved by certified reference material (CRM) and ICP-MS.

Keywords:

Selenium , Inorganic speciation , Serum and urine , Isopropyl [(IsopropoxyCarbothiolyl) Disulfanyl] Ethane Thioate , Ultrasound-assisted dispersive liquidliquid bio-microextraction