Study On The Oxidation Of Glucosamine

Glucosaminic acid has unique physiological activity. In recent years, it is widely used infood and pharmaceutical fields. However, there is no good chemical synthesis method, andfew reports on determination of glucosaminic acid. In this paper, the main purpose is toexplore a new preparation method of glucosaminic acid from glucosamine and establish anovel process to determine glucosaminic acid.⑴Fresh CuO was used to catalytical oxidation of glucosamine to glucosaminic acid,and the conditions studied by three factors and three levels orthogonal experiments. Theoptimized conditions that obtained were pH10, temperature60℃, reaction time30min,and60%yield of glucosaminic acid was obtained. IR and NMR were used to characterizethe product.⑵Six modified electrodes were applied to the catalytical oxidation of glucosamine in0.1mol·L-1NaOH solution and0.1mol·L-1PBS buffer solution (phosphate buffer solution)respectively. It was found that CuO-MWNTs/GCE (glassy carbon electrode modified by CuOwhich loaded on multi-wall carbon nanotubes), Bi-MWNTs/GCE (glassy carbon electrodemodified by Pd-Bi/MWNTs) and Pd-MWNTs/GCE had no obvious catalytical activity toglucosamine in NaOH solution, but the other three ones did, which were Au electrode,Pd/Au-1(Au electrode electrodeposited with Pd) and Pd/Au-2electrode. In PBS buffersolution, Au and Pd/Au-1had catalytical activity on glucosamine, and Pd/Au-1electrode hadgood stability and reproducibility.⑶The corresponding derivatives of glucosamine hydrochloride and glucosaminic acidwere got by the van Slyke reaction. The optimized operating conditions were as follows:Aminex HPX-87H column was used with differential refractive index detector,35℃, elutedisocratically with5mmol L-1H2SO4, flow rate0.4mL min-1. Under the optimized operatingconditions, the protocols of separation and quantification of glucosamine hydrochloride andglucosaminic acid were established by isocratic HPLC. The corresponding linear equation forglucosamine hydrochloride is A=348.35C+15.03, R2=0.9996, in the range of0-50mmol L-1,and the detection limit is0.014mmol L-1. The corresponding linear equation for glucosaminicacid is A=347.21C+22.58, R2=0.9995, in the range of0-50mmol L-1, and the detection limitis0.034mmol L-1.⑷A spectrophotometric detection method was established, which based on the abilityof glucosaminic acid to form the corresponding lactone at pH1.5, and the lactone can reactwith hydroxylamine base-ferric trichloride color system to form a red-brown complex. Themaximum absorbance of the complex is at500nm. The linear range is from1.0×10-5to9.0×10-5mol·mL-1and the average recovery is99.28%, RSD≤4.91%. The selectivity andsensitivity of this method are satisfactory and the results are stable. This method can besuccessfully applied to detection of actual sample.