Determination of vitamin B1 with 12-tungstophosphoric acid by resonance Rayleigh scattering method

Abstract

In pH 0–1.0 HCl medium, 12-tungstophosphoric acid (TP) could react with vitamin B₁ (VB₁) to form a 1 : 3 ion-association complex. As a result, new spectra of resonance Rayleigh scattering appeared and their intensities were enhanced greatly. The maximum wavelength was located at 335 nm. The scattering intensities were proportional to the concentration of VB₁ in the range of 0.25–1.75 μg mL⁻¹. Therefore, a new method for the determination of VB₁ was established. The method had high sensitivity and good selectivity, and the detection limit (3σ) was 0.94 ng mL⁻¹. It was applied to the determination of VB₁ in urine samples and VB₁ tablets, which showed that the results were consistent with those of the China pharmaceutical method. The recovery was between 97.3%–99.0%, and the relative standard deviation (RSD) was between 1.1%–3.4%. Furthermore, the optimum reaction conditions, the RRS spectra characteristics, the reaction mechanism and the reasons for enhancement of scattering were evaluated.