1, this method is suitable for the determination of the dynamic HPMC viscosity of non-Newtonian fluids (polymer solution, suspension, emulsion dispersion liquid or surfactant solution, etc.).
2. Instruments and appliances
2.1 Rotary viscometers (NdJ-1 and NDJ-4 are used according to Chinese Pharmacopoeia) Viscometers with frequency stabilizing measures (such as NDJ-1 and NDJ-4) shall be reserved. 8 g hydroxypropyl methyl cellulose sample was accurately weighed and put into a dry, peeled 400mL tall beaker. Add about IOOidL of hot water at 80-90 degrees Celsius and stir lOmin to disperse evenly. Add cold water to total 400mLo and stir continuously for about 30min to become 2% (W/W) solution, put into the ice bath in the refrigerator to cool to the surface of thin ice, take zhu into the constant temperature tank so that the central temperature is constant temperature to 20± 0.1 degrees to detect viscosity.
3.1 Installation and operation of the instrument shall be carried out in accordance with the operating instructions of the instrument, and the appropriate rotor and speed shall be selected according to the viscosity range of the tested product and the provisions of the pharmacopoeia under the text of the product.
3.2 Adjust the constant temperature water temperature according to the determination under the item of each drug.
3.3 The test hydroxypropyl methylcellulose HPMC product was placed in the container specified by the instrument, and the deviation Angle (Q) was measured according to law after 30 minutes of constant temperature. Turn off the motor and start it again for measurement. The difference between the measured value and the average value shall not exceed ±3% of the average value. Otherwise, a third measurement shall be made.
3.4 Calculate the mean value of the two tests according to the formula to obtain the dynamic viscosity of the tested product.
4. Record and calculate
4.1 Record the rotary viscometer model, rotor number and speed used, viscometer constant (K value), measured temperature, and a value measured each time.
4. 2 Calculation formula
Dynamic viscosity (MPA-S) two Ka
Where K• is the viscometer constant a measured with a standard liquid of known viscosity is the deflection Angle