An immediate luminescence enhancement method for determination of vitamin B₁ using long-wavelength emitting water-soluble CdTe nanorods

A method for determination of vitamin B₁ has been developed that is based on the enhancement effect of vitamin B₁ on the luminescence of water-soluble CdTe nanorods modified with thioglycolic acid and cysteine. The effect of variables including the size of the nanorods on the enhancement of luminescence have been investigated. A preliminary mechanistic study showed that the passivating action of vitamin B₁ on the surface of the CdTe nanorods is likely to be responsible for the enhancement. Interferences by shortwave fluorescence are effectively eliminated because measurements are performed in the near-infrared. Due to the near-infrared measurement character, the fluorescence interference of vitamin B₂ can be effectively eliminated. Under the optimum conditions, the extent of luminescence enhancement is proportional to the concentration of vitamin B₁ in the range from 0.1 to 3.0 μmol L^-1 and the detection limit is 0.03 μmol L^-1. The relative standard deviation for 2.0 μmol L^-1 vitamin B₁ is 1.3% (n = 6). The method is highly sensitive and selective, avoids the sample treatment needed in other procedures, and can be applied to the determination of vitamin B₁ in real samples with satisfactory results.