HPMC factory teaches you to test the viscosity of HPMC

Shandong chuangyao Biotechnology Co., Ltd. is specialized in the R & D, production and sales promotion of hydroxypropyl methylcellulose products. The purity of hydroxypropyl methylcellulose is the most concerned product topic for manufacturers and users. Below we hydroxypropyl methyl cellulose manufacturers to give a detailed introduction, hoping to play a role in reading.

Purity determination of hydroxypropyl methylcellulose

principle

HPMC is insoluble in 80% ethanol. After dissolving and washing for many times, the 80% ethanol soluble substance in the sample is separated and removed to obtain the pure HPMC.

reagent

Unless otherwise specified, only reagents confirmed to be analytically pure and distilled or deionized water or water of equivalent purity shall be used in the analysis.

95% ethanol (GB / T 679).

Ethanol, 80% solution, dilute 840ml of 95% ethanol (e.2.1) to 1 l with water.

Bimi (GB / T 12591).

instrument

Common laboratory instruments

Magnetic heating stirrer, stirring rod length about 3.5cm.

Filter crucible, 40 ml, pore size 4.5 μ M-9 μ M.

Glass Watch dish, diameter 10 cm, with holes in the center.

Beaker, 400ml.

Constant temperature water bath.

The oven can control the temperature at 105 ℃± 2 ℃.

program

Accurately weigh 3G sample (accurate to 0.001g) in a beaker with constant weight, add 150ml of 80% ethanol at 60 ℃ ~ 65 ℃, put it into a magnetic rod, place it on the magnetic heating stirrer, cover the watch glass, insert a thermometer in the central hole, turn on the heating stirrer, adjust the stirring speed to avoid splashing, and maintain the temperature at 60 ℃ - 65 ℃ for 10min.

Stop stirring, place the beaker in a constant temperature water bath of 60 ℃～ 65 ℃, let the insoluble matter settle, and pour the supernatant into the filter crucible with constant weight as much as possible.

Add 150 ml of 80% ethanol at 60 ℃ ~ 65 ℃ into the beaker, repeat the above stirring and filtering operations, and then wash the beaker, watch glass, stirring rod and thermometer with about 250 ml of 80% ethanol at 60 ℃ ~ 65 ℃ with the aid of washing bottle, so that the insoluble matter is completely transferred into the crucible, and the contents of the crucible are further washed. Suction filtration can be used in this operation, and the cake should not be sucked dry. If there are particles passing through the filter, the suction should be slowed down.

Note: it should be ensured that the sodium chloride in the sample is completely washed away by 80% ethanol. If necessary, 0.1mol/l silver nitrate solution and 6mol / L nitric acid can be used to test whether the filtrate contains chloride ions.

At room temperature, the contents of the crucible were washed twice with 50 ml 95% ethanol, and then washed twice with 20 ml ethylmi. The time of suction filtration should not be too long. Put the crucible in a beaker and heat it on the steam bath until there is no ethylmi smell.

Note: it is necessary to wash with ethylene Mi to completely remove ethanol from the insoluble substance. If ethanol is not completely removed before oven drying, it is impossible to completely remove ethanol during oven drying.

Put the crucible and beaker in an oven at 105 ℃± 2 ℃ for 2 h, then transfer them into a dryer to cool for 30 min and weigh them. Repeat drying for 1 h and cool to weigh until the mass change does not exceed 0.003 G. If the mass increases after drying for 1 h, the lowest mass observed shall prevail.

Result calculation

The purity of HPMC is calculated by mass fraction P, and the value is expressed in%

M1 -- mass of insoluble matter after drying, unit: G;

M0 -- mass of test sample, unit: G;

W0 -- moisture and volatile content of the sample,%.

Take the arithmetic mean value of two parallel determination results rounded to one decimal place as the determination result.

Precision

The absolute difference between the two independent determination results obtained under the condition of repeatability is not more than 0.3%, and the premise is that the absolute difference is not more than 5% when it is greater than 0.3%.

For more questions about HPMC products, please pay attention to HPMC manufacturer Shandong chuangyao Biotechnology Co., Ltd.