Analysis and test of HPMC manufacturers

The analysis items of HPMC include methoxy content, hydroxypropyl content, viscosity, moisture, ash, chloride, alkalinity, iron content, heavy metal content, pH value, solid content and relative density. Among them, the determination of methoxy content and hydroxypropyl content is much more complicated than that of methyl cellulose and hydroxypropyl cellulose, because hydroxypropyl methyl cellulose is a mixed ether, the results of the two items must be corrected before the correct results of the two items can be obtained. For detailed analysis procedures of these projects, please refer to the standard method of hydroxypropylmethylcellulose test in American Society for testing and materials (ASTM) published in 1976.

For example, according to the requirements of different applications, there are some specific test items, such as the determination of salting out point and fiber rate.

(1) The determination of hydroxypropyl content adopts the oxidizing property of chromic acid to oxidize it into acetic acid. Then the uncorrected hydroxypropyl content (%) is obtained by titration with alkali according to the standard method. Then the corrected hydroxypropyl content must be obtained by measuring the hydroxypropyl value of the blank sample of methylcellulose by the same method.

(2) The methoxyl content is determined by using hydroiodic acid to form alkyl sulfonate, which is carried away by carbon dioxide gas flow, passed through the condenser, and finally absorbed by bromine solution, acetic acid and sodium acetate. After being absorbed, alkyl iodides are oxidized to alkyl iodates. Excess iodine was reduced by formic acid; Iodometric method of potassium iodide and standard thiosulfate was used for the determination of iodate.

For more information, please pay attention to HPMC manufacturer Shandong chuangyao Biotechnology Co., Ltd www.cyhuagong.comFor more information, please pay attention to HPMC manufacturer Shandong chuangyao Biotechnology Co., Ltd www.cyhuagong.com