Abstract: Based on the chemiluminescence (CL) catalysis of vitamin
B₁₂ (VB₁₂ in luminol-H$_{2}$O$_{2}$ system, a novel
capillary electrophoresis-chemiluminescence (CE-CL) method was
developed for the accurate determination of this important nutrient
substance. First of all, sodium hydrosulfite
(Na$_{2}$S$_{2}$O$_{4})$ was found to be used as an competent
reduction reagent to pre-reduce VB₁₂(Co(III)) into
VB₁₂(Co(II)), which produced strong CL emission in the CL
reaction of luminol-H$_{2}$O$_{2}$. In this process, some
interfering CL noise was observed and capillary electrophoresis (CE)
was taken to remove it by efficient separation. In this way,
VB₁₂ could be reduced gently and determined accurately by the
catalyzed CL signal with our lab-constructed CE-CL system. The
proposed CE-CL determination could be finished in 20 min with a
detection limit (LOD) of 2$\times $10$^{-7}$ mol/L ($S$/$N$=3), a
linear range from 6$\times $10$^{-7}$ to 6$\times$10$^{-4}$ mol/L
($r^{2}$=0.968) and a relative standard deviation (RSD) of 2.4{\%}
($n$=9). Utilizing this method, satisfactory results were obtained
by testing VB₁₂ tablets with a recovery of 97{\%}$\sim
$106{\%}. Compared to previously reported CL analysis of VB₁₂,
we dealt with the interference components in pre-reducing solution
for the first time to gain more reliable data with convenient
operations.

Key words: vitamin B₁₂, chemiluminescence, capillary electrophoresis, sodium hydrosulfite