Degradation Kinetics of Sinomenine Hydrochloride Aqueous Solution

OBJECTIVE:To investigate the degradation kinetic characteristics of Sinomenine hydrochloride aqueous solution.METHODS:The colorimetric method was used to determine the degradation kinetic parameters of Sinomenine hydrochloride aqueous solution under various pH solutions,various ionic strength and various dielectric constant conditions.RESULTS:With comparative regression analysis of linear fitting,the degradation kinetic order of Sinomenine hydrochloride aqueous solution was determined as n=1.The higher the pH in Sinomenine hydrochloride aqueous solution was,the higher the degradation kinetic rate constant was.The Sinomenine hydrochloride aqueous solution degraded slowly at the field of lower pH(pH3) and the degradation kinetic rate constant was relatively stable and low at pH3.9～5;The degradation reaction accelerated at the field of higher pH(pH5).The higher the ionic strength of Sinomenine hydrochloride aqueous solution was,the higher the degradation kinetic rate constant was.As the dielectric constant of solution increased,so did the degradation kinetic rate constant.CONCLUSION:It was found that the degradation of Sinomenine hydrochloride followed apparent first-order kinetics.The degradation kinetic rate was affected by pH remarkably and positively correlated with ionic strength and dielectric constant.