SU877412A1 - Method of determination of methionine content in feeds - Google Patents

Description

(54) METHOD FOR DETERMINATION OF METIONINE

one

The invention relates to a technique for the quantitative determination of methionine used in the control of product quality in the feed mill industry.

A known method for determining methionine in feed is based on the interaction of methionine with a reagent containing acetylacetone, formaldehyde and pyridine, followed by photometric measurement of the obtained colored compound l.

The disadvantage of this method is its low accuracy and sensitivity.

Closest to the present invention is a method for determining methionine in feeds by treating an analyte solution with sodium nitroprusside in an alkaline medium, followed by photometry of the resulting colored compound, 2,

The disadvantage of this method is its low accuracy.

The purpose of the invention is to improve the accuracy of the method.

This goal is achieved by the fact that in the method of determining methioni-. on in feed, including photometry of the colored solution, analyzed in the feed

Substance I is treated with water at pH 2-3, filtered, the filtrate is treated with a solution of phosphorus-tungstic acid, filtered, the filtrate is treated successively with solutions of alkali, sodium nitroprusside, amino-acetic acid, followed by treatment while cooling the resulting mixture with concentrated o-phosphoric acid and photometricizing the obtained colored solution.

Example. A feed sample containing 80 mg of methionine is placed

15 to a volumetric flask with a capacity of 500 ml, add 300-350 ml of water, adjust the pH to 2-3 with diluted hydrochloric acid (50 Mji) and shake on a rocker for 60 minutes. Then add the volume

20 water up to the mark, mixed and filtered through a paper folded filter. 20 ml of the filtrate are transferred to a 50 ml conical flask, 2 ml of 4% aqueous solution is added.

25 phosphorus-tungsten acid, mixed and after 20 minutes filtered through a paper folded filter.

Take 3 ml of the filtrate obtained in a 50 ml conical flask, add 2 ml of water, 1 ml of 20% solution.

Soda sodium thief, 0.1 ml of 10% sodium nitroprussnd solution and stirred, after 10 min, add 2 ml of 3% amino acetic acid solution and again leave for 10 min from time to time, stirring time. Thereafter, while stirring, cooling, 2 ml of 85% o-phosphoric acid are poured, and after 5 minutes, the optical density of the colored

Found methionine,%, according to the method

solution on a photoelectrocolorimeter (wavelength 530 nm) in cuvettes with a 10 mm face width against a control containing 3 ml of filtrate and the rest are reagents other than sodium nitroprusside. The calculation of the methionine content is carried out according to a calibration curve.

The results are shown in the table (methionine was introduced in the premix 7.0%, in the mixed feed 0.5%).

The results of the table show that the content of methionine in the premixes, as determined by the proposed method, is 7.03% and in the mixed feed is 0.51%, and when determined in a known manner, 40 7.96 and 1.27%, respectively, with a large deviation to 0.93%,

Claims (1)

Invention Formula The method of determining methionine in feed, including photometry of the colored solution, is also distinguished by the fact that, in order to increase the accuracy of the method, the analyte is treated with water at pH 23, filtered, the filtrate is treated with a solution of phosphorus-tungstic acid, filtered, the filtrate is treated sequentially with alkali solutions , sodium nitroprusside, amino acetic acid, followed by treatment with cooling of the mixture obtained with concentrated of. phosphoric acid and photometry of the resulting colored solution. Sources of information taken into account in the examination 1, Korenman I.M. Photometric analysis, M, Himi, 1970, s, 161. 2, Ibid, p.272 (prototype).