Anti-Vitamin B12 polyclonal antibody

A HPLC-UV/Vis method using a two-column strategy with a switching valve for on-line sample cleanup was developed for the determination of cyanocobalamin (CN-Cbl/Vitamin 1312) in multivitamin dietary supplement tablets. The method uses two columns: an Agilent Zorbax C8 (150 mm x 4.6 mm, 5 mu m particle size) reversed-phase column and a Waters Symmetry C18 (150 mm x 4.6 mm, 5 mu m particle size) reversed-phase column. Chromatographic separation was achieved using a programmed gradient mobile phase consisting of (A) 0.1% formic acid in water and (B) 0.1% formic acid in acetonitrile. Because of the low levels of Vitamin B-12 in the samples, large injection volumes, and thus much interfering material, must be used to exceed the limit of quantitation (LOQ) by UV detection. A switching valve was used to divert most of these early eluting interfering materials to waste, effecting on-line sample clean-up without excessive sample preparation steps. The recovery of CN-Cbl in the method was 99.5% and the LOQ was 10 ng per injection. The method was successfully applied to the analysis of the NIST SRM 3280 multivitamin/multimineral dietary supplement tablet. The method is specific, precise, and accurate for the intended use. Compared to off-line sample clean-up procedures, it offers the advantage of being easier, more economical, and less time-consuming.

The whole brain content of vitamin B-12 (VB12) in the rat was assayed by the chemiluminescent immunoassay at 4 h intervals in 12:12 h light-dark cycles (LD) and five different circadian times (CTs) under constant dim illumination (dim LL). In LD-entrained rats, the content of VB12 exhibited a day-night rhythm with a peak 2 h after the dark onset time and a trough 2 h before the light onset time. In freerunning rats under dim LL, the content of VB12 also exhibited a circadian variation with a peak ca. 2 h after the activity onset time (CT14) and a trough ca. 12 h after the activity onset time (CT 0). These findings clearly indicate that the brain VB12 content decreased during the active phase and increased during the resting phase regardless of the lighting schedule. On the other hand, the drinking behavior, as an index of the intake activity, was observed less frequently in the light phase of LD cycles and the resting phase of dim LL. Since most of the digested VB12 is known to be continuously stored in the liver, it is demonstrated that the rhythm of the brain content of VB12 may be caused by brain consumption of VB12 during the active phase and the transportation from the peripheral storage during the resting phase, independent of intake activities. (C) 1997 Elsevier Science Ireland Ltd.