Determination of thiamine (vitamin B1) in pharmaceutical tablets and human urine by titania-based ligand-exchange hydrophilic interaction chromatography

Abstract

A new method for the determination of thiamine (vitamin B₁) using high performance liquid chromatography (HPLC) on a titania-based column with UV detection has been developed. The influence of acetonitrile (MeCN) percentage in mobile phase, phosphate buffer concentration and buffer pH on the retention of thiamine were investigated. Thiamine retention on titania was ascribed to the cooperation of hydrophilic interaction and ligand-exchange. By altering the buffer concentration, the retention of thiamine on titania was easily adjusted. Isolation of thiamine in pharmaceutical tablets and human urine was achieved within 10 min. Neither complex pretreatment procedures during the sample preparation nor ion-pair reagents in the eluent were needed to retain thiamine. Hydrophobic or non-titania-affinitive interferences were weakly retained, while both the hydrophilic and titania-affinitive thiamine obtained moderate retention (retention factor k = 1.2). The method presented good linearity (R² = 0.9997) toward thiamine in the range of 0.25–125 μg mL⁻¹. The limit of detection (3σ) for thiamine was 75 ng mL⁻¹. The precision (RSD) for 11 replicate detections of 5 μg mL⁻¹thiamine was 2.3%. The recovery of spiked thiamine in vitamin B₁ tablets, compound vitamin B tablets and human urine ranged from 96 to 114%. The proposed titania-based HPLC method was employed to monitor the time-dependent concentration of thiamine in human urine from a healthy volunteer after oral medication of vitamin B₁ tablets. This finding is not only a supplement to the detecting methods for thiamine, but also adds new merits to titania-based stationary phase.