Determination of Kinematic Viscosity of Medicinal Liquid Drugs
Kinematic viscosity is a critical physical index of medicinal liquid drugs, which directly reflects the fluidity, purity and quality stability of pharmaceuticals, and serves as a key testing item for drug inspection and quality control. In accordance with Method 1 for Determination of Viscosity (General Chapter 0633) in the Chinese Pharmacopoeia 2020 Edition, the kinematic viscosity of a fluid can be obtained by measuring the time required for a fixed volume of liquid to flow through a capillary under gravity via the relative method, so as to ensure that pharmaceuticals meet pharmacopoeia standards and clinical application requirements.
Experimental Purpose
To accurately determine the kinematic viscosity of medicinal liquids and verify whether the purity, concentration and quality of pharmaceuticals meet the standards, so as to avoid abnormal viscosity affecting the stability of pharmaceutical preparations, dosing accuracy and therapeutic efficacy. This test is carried out in strict compliance with General Chapter 0633 of the Chinese Pharmacopoeia 2020 Edition, using the ST204B Automatic Ubbelohde Kinematic Viscometer. The instrument is specially designed for the pharmacopoeia method, features fully automatic operation, and delivers accurate and reliable results.
Experimental Sample
Medicinal liquid to be tested (meets the requirements of pharmacopoeial test samples)
Experimental Instruments
1. ST204B Automatic Ubbelohde Kinematic Viscometer
2. Ubbelohde capillary viscometer, cleaning reagents, waste discharge device, USB flash drive
Experimental Steps
1. Select a qualified Ubbelohde capillary viscometer, fix the optical fiber sensors accurately at the upper and lower detection marks of the viscometer, and mount the viscometer on the special fixture of the instrument.
2. Connect the cleaning reagent bottle, waste discharge tube and filtration pump, and add sufficient water or transformer oil as the constant temperature medium into the constant temperature bath of the instrument. It is strictly prohibited to heat the bath without medium.
3. Draw an appropriate amount of test sample with the sample injection device and inject it into the viscometer tube, then close the top cover of the bath.
4. Turn on the instrument power, enter the 7-inch color touch screen operation interface, and input the viscometer constant, tube diameter, sample number, constant temperature time, test times, cleaning and drying parameters, and target test temperature in the Parameter Settings.
5. Enter the System Settings, turn on the heating device, enable the cooling function and printer if necessary, and start heating self-tuning when temperature fluctuation is large. Wait until the bath reaches and stabilizes at the set temperature.
6. Tap Channel 1/2 on the main interface; the instrument will automatically perform constant temperature, automatic extraction, automatic timing, three repeated measurements, automatic calculation of average viscosity, and automatic printing of results.
7. After the experiment, the instrument will automatically discharge waste, clean and dry the viscometer tube without manual supervision throughout the process.
8. View records on the Historical Data interface, insert a USB flash drive to export and save data in CSV/Excel format.
Core Instrument Parameters and Result Evaluation
- Temperature control range: Room temperature +5℃ ~ 100.0℃ (special range: 0℃ ~ 100.0℃), temperature control accuracy: ±0.1℃
- Measuring range: 0.6 ~ 17000 mm²/s, timing accuracy: ≤ ±0.01% within 60 minutes
- Capable of storing 199 sets of historical data, supports printing and USB flash drive export, meeting pharmacopoeial traceability requirements
The test results show that the kinematic viscosity of the tested medicinal liquid falls within the range specified by the pharmacopoeia, the error of parallel tests meets the standard, and the data are stable with good repeatability, fully satisfying the requirements of medicinal testing.