METHOD OF DETERMINING CONTENT OF ASCORBIC ACID IN PLANT MATERIAL Russian patent published in 2016 - IPC G01N33/02 

FIELD: pharmaceutics.

SUBSTANCE: invention relates to pharmacy, in particular to determination of ascorbic acid in plant material by photochemical titration. That is an aliquot of hydrochloric acid extraction of vegetal raw materials in the reaction vessel containing photogenerated iodine. Photogenerated iodine is produced by blowing with air for 1-2 minutes of a reaction mixture consisting of 0.5 M solution of potassium iodide, solution of acetate buffer with pH 5.6 and eosin sensitiser followed by exposure to stabilised source of light, wherein current change is measured in cell. When constant current is achieved, blowing of reaction mixture with air for 2-3 minutes is repeated and irradiation of stabilised source of light until initial quantity of iodine in reaction vessel is achieved. Time of recovery of iodine generation spent on replenishing its decrease is measured. Content of ascorbic acid is calculated by formula: where C.d. is measuring sensitivity of device, mmol/mcA (6.71·10^-4) or mmol/min (1.97·10^-2); is change of current in circuit of administering aliquot portion of analysed solution, mcA; is generation time, s; M is molar mass of ascorbic acid, 176.12 g/mol; V_f is volume of measuring flask, in which solution of analysed sample is diluted, ml; m is batch of sample, g; V_a is volume of aliquot part, ml.

EFFECT: invention provides a simple, fast and accurate method of determining ascorbic acid in analytical laboratories.

1 cl, 3 tbl, 2 ex