title: Ion pair hollow fiber liquid-liquid-liquid microextraction combined with capillary electrophoresis-ultraviolet detection for the determination of thyroid hormones in human serum.
abstract: In this study, a novel, inexpensive, sensitive and selective analytical method that combines ion pair hollow fiber liquid-liquid-liquid microextraction (IP-HF-LLLME) with capillary electrophoresis-ultraviolet detection (CE-UV) was developed for the simultaneous determination of six thyroid hormones (including diiodothyronine (T₂), 3,3,5-triiodo-l-thyronine (T₃), 3,5,3,5-tetraiodolthyronine (T₄), 3,3,5-triiodothyronine (rT₃), monoiodotyrosine (MIT) and diiodotyrosine (DIT)) in human serum samples. By the addition of a low concentration of sodium dodecyl sulfate (SDS) into the donor phase as an ion pair reagent, octanol as the organic extraction solvent and 30 mmol/L Na₂CO₃ as acceptor phase, six analytes with different polarity and water solubility were successfully extracted simultaneously using HF-LLLME. To the best of our knowledge, this is the first time that a liquid phase microextraction technique was proposed for the extraction of thyroid hormones in real samples. The CE separations were investigated in detail. When 20 kV of voltage was applied, the six compounds were separated within 13 min in 25 mmol/L phosphate buffer (pH 2.15) containing 10% (v/v) acetonitrile and 0.5% (m/v) polyethylene glycol (PEG). Under the optimized conditions, enrichment factors (EFs) ranging from 183- to 366-fold were obtained and the limits of detection (at a signal-to-noise ratio of 3) were at sub μg/L level. The established IP-HF-LLLME-CE-UV method was successfully applied to simultaneous determination of thyroid hormones and relative compounds in human serum samples with good recoveries for the spiked samples.
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, China.
authors.forename: Pingjing
authors.initials: P
authors.lastname: Li
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, China. Electronic address: binhu@whu.edu.cn.
authors.forename: Bin
authors.initials: B
authors.lastname: Hu
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, China.
authors.forename: Man
authors.initials: M
authors.lastname: He
authors.affiliation: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), Department of Chemistry, Wuhan University, Wuhan 430072, China.
authors.forename: Beibei
authors.initials: B
authors.lastname: Chen
mesh_terms: D003902:Detergents / Q000737:chemistry; D019075:Electrophoresis, Capillary; D006801:Humans; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D059627:Liquid Phase Microextraction; D059629:Signal-To-Noise Ratio; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D012997:Solvents / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D013963:Thyroid Hormones / Q000097:blood / Q000302:isolation & purification*
chemical_list: D003902:Detergents; D012997:Solvents; D013963:Thyroid Hormones; D012967:Sodium Dodecyl Sulfate
keywords: CE-UV; Human serum; Ion pair hollow fiber liquid–liquid–liquid microextraction; Thyroid hormones and relevant compounds