Dissolution tester · Calibration procedure
Rotation speed
Checks that every shaft turns at the set speed, using a calibrated tachometer, at the speeds your methods use.
PURPOSE
Why this is checked
Agitation speed has a direct effect on the dissolution rate. A shaft running fast or slow gives a biased result.
Frequency
Typically every 6 months and after drive maintenance; some labs also check speed before each test.
Learn how the Dissolution tester worksYOU WILL NEED
Standards & tools
- Calibrated optical or contact tachometer, traceable to national standards
BEFORE YOU START
Prerequisites
- Paddles or baskets fitted
- Vessels filled with medium or water as your SOP requires
- Apparatus warmed up
PROCEDURE
Step by step
- 1Set the speed to the lowest routine value (e.g. 50 rpm) and allow it to stabilise.
- 2Measure the speed of each shaft with the tachometer and record it.
- 3Repeat at the other speeds used (e.g. 75 and 100 rpm).
- 4Calculate the % deviation from the set value for each reading.
RECORD
Example observation table
| Position | Set (rpm) | Observed (rpm) | % deviation |
|---|---|---|---|
| 1 | 50 | 49.9 | −0.2 |
| 2 | 50 | 50.1 | +0.2 |
| 3 | 50 | 50.0 | 0.0 |
| 4 | 50 | 49.8 | −0.4 |
| 5 | 50 | 50.2 | +0.4 |
| 6 | 50 | 50.0 | 0.0 |
| 1 | 100 | 99.6 | −0.4 |
| 2 | 100 | 100.3 | +0.3 |
| 3 | 100 | 100.1 | +0.1 |
| 4 | 100 | 99.8 | −0.2 |
| 5 | 100 | 100.4 | +0.4 |
| 6 | 100 | 99.9 | −0.1 |
CALCULATION
How to calculate the result
% deviation = (Observed − Set) ÷ Set × 100
- Set 50 rpm, observed 49.8 rpm at position 4
- % deviation = (49.8 − 50) ÷ 50 × 100 = −0.4%
- Within ±4% (±2 rpm at 50 rpm)
ACCEPTANCE CRITERIA
Pass if
- USP: within ±4% of the stated speed.
- Enhanced mechanical calibration practice often uses a tighter limit, such as ±2% or ±2 rpm; follow your SOP.
IF IT FAILS
What to do
- Stop using the apparatus and label it.
- Check the drive belt, motor and speed controller; get it serviced.
- Recalibrate and assess the impact on earlier results.
MORE
Other Dissolution tester calibrations
In LimsPulse · Calibration Management
LimsPulse schedules this calibration, records the result against limits, and blocks the instrument everywhere if it fails or goes overdue.