Resonance Rayleigh-scattering method for the determination of vitamin B1 with Methyl Orange

In a pH 2.3 - 3.0 acid medium, the resonance Rayleigh scattering (RRS) intensity is greatly enhanced when vitamin B, reacts with Methyl Orange to form an ion-association complex. The maximum RRS peak appears at 588 nm, another higher peak is at 403 nm and there are two smaller RRS peaks at 800 nm and 288 nm. The RRS intensity is directly proportional to the concentration of vitamin B-1 in the range of 0 - 400 ng ml(-1). The method has high sensitivity and the detection limit (3sigma) for vitamin B-1 is 7.2 ng ml(-1). The effects of coexisting substances on the determination of vitamin B-1 were investigated, and the results show that this method has good selectivity and can be applied to the direct determination of vitamin B-1 in composite vitamin B tablets and multivitamin tablet samples.