METHOD OF EXTRACTING VITAMIN B FROM AQUEOUS SOLUTION Russian patent published in 2011 - IPC C07H23/00 

FIELD: chemistry.

SUBSTANCE: method involves preparation of a water-salt solution of vitamin B₁₂ through dissolution thereof in a saturated solution of a salting-out agent, extraction and analysis of equilibrium aqueous phase, wherein the extraction agent used is aqueous solution of polyethylene glycol with molar mass of 5000 g/mol, the salting-out agent used is ammonium sulphate. The water-salt mixture of vitamin B₁₂ with pH 5.3±0.3 is prepared by putting a sample of vitamin B₁₂ with pharmacopoeial purity, taken on analytical balances, into a measuring flask and bringing to the mark with a saturated solution of ammonium sulphate. Vitamin B₁₂ is then extracted with aqueous solution of polyethylene glycol with concentration of 10^-4 mol/dm³ by adding to the obtained vitamin B₁₂ solution aqueous solution of polyethylene glycol in volume ratio of the water-salt solution of vitamin B₁₂ to the polymer solution equal to 10:1 and then extracted for 6-7 minutes until establishment of inter-phase equilibrium. For stratification of the system, the solution is put into a laboratory centrifuge for 5-7 minutes rotating at 1000 rpm. The water-salt phase is then separated from the water-organic phase and then analysed via UV spectrophotometry. A calibration curve of optical density of the water-salt solution versus concentration of vitamin B₁₂ is then plotted. Optical density of the water-salt solution is then measured on a UV spectrophotometre in a quartz cell with thickness of the light-absorbing layer equal to 1 cm and wavelength of 360 nm. Concentration of vitamin B₁₂ in the aqueous solution is then found using the calibration curve.

EFFECT: high distribution and concentration coefficients, faster and safer process.

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