Determination of Trace Vanadium(V) by Solid Substrate Room Temperature Phosphorimetry Based on the Catalyzed Reaction of Potassium Bromate Oxidizing Safranine O Activated by Vitamin C

Abstract

A new method for the determination of trace vanadium(V) by solid substrate room temperature phosphorimetry (SS‐RTP) has been established. It is based on the facts that in the presence of sulfuric acid and sodium dodecyl benzene sulfonate (DBS), vanadium activated by vitamin C (Vc) can catalyze potassium bromate to oxidize safranine O (R), the oxidation products of safranine O can emit intense and stable solid substrate room temperature phosphorescence (SS‐RTP) on nitrocellulose membrane. The catalytic reaction is a first‐order reaction, with a reaction rate constant (k) of 7.3 × 10⁻⁴ sec⁻¹, and the apparent activation energy (E) is 46.09 kJ/mol. The phosphorescence intensity (ΔI _p) will be increased 10 times if Vc is added. The linear range of this method is 1.6–16.0 fg/spot within which ΔI _p obeyed Beer's Law, the detection limit (LD) is 0.38 fg/spot (0.4 µL sample solution per spot), and the regression equation for working curve is ΔI _p = 52.17 + 3.181m _V(V) (fg/spot), n = 6, correlation coefficient r is 0.9993. This sensitive method has been applied to the determination of trace vanadium in tea and human hair samples successfully. The mechanism of the catalytic reaction was also discussed.

Keywords:

• Vanadium
• Safranine O
• Solid substrate room temperature phosphorimetry
• Catalysis

Acknowledgments

This work was supported by the Chinese National Natural Science Foundation (Grant no. 20175011) and Fujian Province Natural Science Foundation (Grant no. C0110028).