简单给你翻了翻,充当个参考吧.
另外,你们的中文描述也有问题,里面很多物质和参数的描述需要写清楚些.工艺报告是一个需要标准化的东西,还是严谨些好.
After investigating the preparation & quality test processes of acetylcysteine,we made preliminary analysis and obtained the following possible reasons:
RSH in acetylcysteine structure can easily become ionized in water solution,releasing one proton while forming one RS-.Thus –SH in cysteine can be easily oxidized and converted into a more stable bisulphide （-S-S-）,cystine.
So in acid water solution,N,S-diacetyl-l-cysteine (Impurity D) can convert into N,N-diacetyl-l-cystine (Impurity C).We tested acetylcysteine according to HPLC method described in EUP [ACN:H2O (using H3PO4 to adjust pH value to 3.0)=3:97,sample dissolved in 0.01 mol/L HCl aq] and found that,content of impurity C inside became higher after the sample solution was placed for certain time.
Our own established test method for acetylcysteine also proved,pH value influences the impurity content.No matter in acid or basic environment,the impurity content would increase.High temperature above 80℃ will definitely increase the impurity content.Oxidization creates even a bigger influence,it is good to see that you set nitrogen-protection for the preparation process.
In your report you described,“Adding 0.3m HCl aq into the acetylcysteine solution (volume amount equivalent to 0.8g) till pH value reaches 2”,we think the actual pH value might be lower,while with a higher converted amount.In addition,high-temperature sterilization was needed during the preparation,content of N,N-diacetyl-l-cystine (impurity C) might be even higher.
We suggest a modification of the preparation technology,in order to prevent impurity D and B (cysteine) from converting into impurity C.
Above analysis is based on our test results of acetylcysteine content and its thermal-stability.Since our company is a raw substance manufacturer and not adept at preparation technology,this analysis report is for your reference only.