Taurine determination by capillary electrophoresis with laser-induced fluorescence detection: from clinical field to quality food applications

Abstract

In this work we describe a new method for taurine quantification in plasma by capillary electrophoresis laser-induced fluorescence detection. Taurine is derivatized with fluorescein isothiocyanate at 100 degrees C in 20 min. These conditions allow to reduce the pre-analytical times and to derivatize quantitatively the taurine contained in the reaction mixture, contrary to the room temperature derivatization commonly adopted. FITC-taurine adduct is analyzed in an uncoated fused-silica capillary, 75 mum ID and 40 cm effective length using a 20 mmol/L tribasic sodium phosphate buffer pH 11.8, at 22 kV. To avoid the typical problems due to instability of FITC-adduct, we use the homocysteic acid as internal standard. The loss of FITC-taurine signal during the sequence analysis is compensated by the same loss of FITC-internal standard adduct, thus giving a noteworthy improvement in the assay precision. The method shows a good reproducibility of the migration times (coefficient of variation, CV%, 1.93) and the peak areas (CV%, 3.65). Intra- and interassay CV were 4.63 and 6.44%, respectively, and analytical recovery was between 98.1 and 102.3%. Assay application was tested measuring taurine plasma levels in 50 healthy volunteers in which a mean value of 60.2 +/- 17.9 micromol/L was found. Moreover, the applicability of the method was also checked on energy drinks and milk.

Clinical and Biochemical Correlates of Serum L-Ergothioneine Concentrations in Community-Dwelling Middle-Aged and Older Adults

“…Body mass index was calculated using height and weight measurements obtained at baseline and eGFR was calculated using the Modification of Diet in Renal Disease formula [18]. Serum concentrations of the thiols homocysteine (Hcy), cysteine (Cys), glutathione (GSH), cysteinylglycine (CysGly), glutamylcysteine (GluCys), and taurine (Tau) were measured previously by CE-LIF methods, as described by Zinellu et al [19], [20]. eGFR has been shown to be an independent determinant of plasma concentrations of Hcy, Cys and CysGly.…”

Simultaneous and rapid determination of caffeine and taurine in energy drinks by MEKC in a short capillary with dual contactless conductivity/photometry detection

“…0.5 mm into the feed PTFE tube (12) in the injection vessel (2). The injection period is controlled by the time during which the zone of sample solution flows around the capillary injection end; excess separation electrolyte flows out into waste (13) during the injection period.…”

Capillary electrophoresis determination of non-protein amino acids as quality markers in foods

“…), pharmacological properties (liver protection, low blood pressure, etc. ), and pathological effects (change of taurine's levels in tissues and physiological fluids has a close relationship with different diseases such as Alzheimer, cardiovascular diseases or epilepsy, among others) [31]. Nowadays, the high consumption of energy and sport drinks makes that the normal daily uptake of taurine (one of the main components of these drinks) could be exceeded which can have undesirable effects.…”

“…Bearing in mind this purpose, different strategies based on CZE, MEKC and microchip capillary electrophoresis (MCE) have been proposed. For instance, a CZE method with LIF detection was developed by Zinello et al [31] to determine taurine in food and clinical samples (energy drinks and cow's milk). The use of a high incubation temperature (100 • C) enabled to reduce the reaction time between fluorescein isothiocyanate (FITC) and taurine from 6-14 h to 20 min After optimization of different electrophoretic variables (buffer concentration, pH, and temperature), the use of 20 mM sodium phosphate at pH 11.8, a temperature of 23 • C, and a separation voltage of 22 kV allowed the analysis of taurine in less than 12 min Different energy drinks were analyzed observing taurine contents in good agreement with the labeled ones.…”