University of North Florida
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Stuart Chalk, Ph.D.
Department of Chemistry
University of North Florida
Phone: 1-904-620-1938
Fax: 1-904-620-3535
Website: @unf

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Classification: Organic compound -> vitamin -> B12

Citations 2

"Selective Spectrophotometric Determination Of Cobalt(II) Using 2,2'-dipyridyl-2-pyridylhydrazone And A Flow Injection Manifold"
Analyst 1995 Volume 120, Issue 5 Pages 1593-1598
Demetrius G. Themelis, George A. Zachariadis and John A. Stratis

Abstract: Sample (100 µL) was injected into a carrier stream (2.6 ml/min) of buffer solution of pH 7.24 (prepared from 0.4 M H3PO4/0.4 M acetic acid/0.4 M H3BO3/0.2 M NaOH) and merged with a reagent stream (0.9 ml/min) of 0.8 mM 2,2'-dipyridyl-2-pyridylhydrazone in aqueous 40% ethanol. The mixture passed through a reaction coil (60 cm x 0.5 mm i.d.) before merging with a second reagent stream (0.4 ml/min) of 1.5 M HCl. The resulting mixture then passed through a second reaction coil (12 cm x 0.5 mm i.d.) after which the absorbance was measured at 500 nm (ε = 42 000 l/mol/cm). A diagram of the manifold used is given. The calibration graph was linear from 0-12 mg/l of Co, the detection limit was 0.017 mg/l and the RSD (n = 5) was 0.4%. The throughput was 90 samples/h. The method was used to determine Co in cyanocobalamin (vitamin B12) after digestion with HNO3/HCl (details given). Recoveries were 98.5-102.7%.
Cobalt(II) Sample preparation Spectrophotometry Buffer

"Study Of Flow Injection Analysis Chemiluminescence System Of 3,5-dibromosalicylfluorone - Hexadecyltrimethylammonium Bromide - Hydrogen Peroxide - Cobalt(II) And Determination Of Trace Cobalt(II) In Vitamin B12 [cyanocobalamin]"
Yaowu Fenxi Zazhi 1990 Volume 10, Issue 1 Pages 26-28
Li, G.H.;Li, M.;Zhang, W.G.

Abstract: Optimum conditions involved 0.15 mM 3,5-dibromosalicylfluorone, 15 mM hexadecyltrimethylammonium bromide, 0.2 M H2O2 and 0.1 M NaOH, and flow rates of 6.4 mL min-1. The calibration graph was rectilinear for 0.5 to 200 ng mL-1 of Co(II). The detection limit was 0.3 ng mL-1, and the coefficient of variation was 0.9%.
Cobalt(II) Chemiluminescence Detection limit Optimization