An immediate luminescence enhancement method for determination of vitamin B.sub.1 using long-wavelength emitting water-soluble CdTe nanorods

A method for determination of vitamin B.sub.1 has been developed that is based on the enhancement effect of vitamin B.sub.1 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 B.sub.1 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 B.sub.2 can be effectively eliminated. Under the optimum conditions, the extent of luminescence enhancement is proportional to the concentration of vitamin B.sub.1 in the range from 0.1 to 3.0 [mu]mol L.sup.-1 and the detection limit is 0.03 [mu]mol L.sup.-1. The relative standard deviation for 2.0 [mu]mol L.sup.-1 vitamin B.sub.1 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 B.sub.1 in real samples with satisfactory results.