Novel assay of thiamine based on its enhancement of total internal reflected resonance light scattering signals of sodium dodecylbenzene sulfonate at the water/tetrachloromethane interface Original Research Article

A new assay of thiamine (Vitamin B1) is proposed by use of total internal reflected resonance light scattering (TIR-RLS) with high selectivity and sensitivity. At pH 3.29 and ionic strength 0.003, the adsorption of thiamine with anionic surfactants, such as sodium dodecylbenzene sulfonate (SDBS), sodium dodecylsulfonate (SDS) and sodium lauryl sulfate (SLS), occurs at the water/tetrachloromethane interface, giving rise to greatly enhanced TIR-RLS signals characterized at 375.0 nm. The enhanced TIR-RLS intensity at 375.0 nm is proportional to the concentration of thiamine in the range 0.12–850 ng ml−1 and its limit of detection (3σ) is 120 pg ml−1. The results of analysis of artificial samples are in agreement with the specified values, and those ones for Vitamin B1 tablets and injection solutions are identical with those obtained according to the method of the Chinese Pharmacopoeia.