Ninhydrin Spectrophotometry Determination Of Lysine Content Of Lysine-sulfate Research

Lysine is essential but not its synthesis, is one of the eight kinds of essential essential amino acids, is the effective use of only L-lysine only, it is known as the "special essential amino acids". Hemoglobin synthesis of lysine in maintaining acid-base balance, the body, promote the regeneration of nerve cells in the brain, involved in fat metabolism, improve human immunity, play an important role in the human body to maintain nitrogen balance and other physiological activities. Lysine high solubility in water, and easy to absorb carbon dioxide in the air, it is difficult to crystallization as a commodity which often hydrochloride or sulfate form.At present, as the product of lysine feed additive used are mainly two categories:L-lysine hydrochloride and L-lysine sulfate. L-lysine sulfate product is not a single compound, which comprises a by-product L-lysine sulfate and other fermentation, lysine content cannot be simply determined by the conventional method of titration. So it is necessary to explore a fast, efficient, accurate inspection method, meet the feed additive lysine sulfate production process.This paper analyzes the experimental conditions for the detection of lysine content by ninhydrin spectrophotometry, and verified the method with national standard of the method, finally analyzes the practical application in lysine production plant, the conclusion as follows:(1) Explore the best experimental conditions method:Lysine concentration in 0.05-0.5mg/ml, lml, color stability, ninhydrin reagent, heating to 100℃ boiled water, heating for 15 minutes, the detection wavelength of 480nm, using 1 cm cuvette, and absorbance detection.10 parallel experiments on 0.3mg/ml lysine standard solution with the new test method, t test and single tail and two tailed by experimental data, showed no systematic error, the measurement results and the standard value of no statistical difference.(2) according to the national standard GB/T27025/ISO17025 "the competence of testing and calibration laboratories Accreditation" "General requirements for the competence of testing and calibration laboratories Accreditation Criteria", and "ICH three party coordination guidelines" to verify the inhydrin spectrophotometry experiments, sample recovery rate was 98%-102%, the precision of the relative standard deviation is less than 2%, between 0.02mg/ml-0.5mg/ml with good linearity, uncertainty of the method in 1.67%, specificity of amino acid experiments show that does not affect the accuracy of. Meet the national standard requirements for new method of inspection regulations.(3) The establishment of inhydrin spectrophotometry determination of lysine for COFCO biochemical L-lysine sulfate workshop for lysine production process testing, experiments show the good use effect. Fermentation sample recovery rate was 98%-104%, the recovery of lysine sulfate production rate in 99-102%.