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Physical Calibration

A mechanical calibration protocol study is currently under way to examine whether mechanical calibration is equal to or better than calibrator tablets. However opinions vary in regards to eliminating or reducing chemical calibrators. 

Calibration parameter Current USP tolerances Point of measurement Proposed tolerances Proposed frequency
Height check 25+-2mm Paddle/basket bottom 25+-2mm At time of use if vessels are removed
Basket wobble +-1mm as runout Bottom of basket rim +-1.0 mm total run out Every 3 months
Rotational speed +-4% Not applicable +-1 rpm Every 3 months
Vessel-shaft centering 2mm from center line Center line 2mm from center line Every 3 months
Vessel temperature 37+-0.5C Not applicable 37+-0.5C At time of use
Bath levelness Level Base plate Level Every 3 months
Shaft wobble no significant wobble 2cm above top of paddle blade <0.5 mm total run out Every 3 months
Paddle/basket dimensions See USP See USP See USP Upon receipt
Vessel dimensions See USP See USP See USP Upon receipt
Degassing technique NCDA2 passes calibration Not applicable NCDA2 passes calibration Once per year
Proposed parameters under investigation        
Paddle/basket examination None Not applicable No gross defects as determined by visual inspection At time of use
Shaft verticality None Above vessel Vertical as measured by a bubble level Every 3 months
Visual inspection of belts; check ball bearings None Not applicable Belts are tight, clean, free of cracks, properly aligned; shaft turns freely Every 3 months


Base plate while operating at 100 rpm <0.2mil Every 3 months

Literature Cited: Pharmacopeial Forum: Volume 26, Number 4

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