Balances and Micropipettes By: Paola Restrepo and Ankita Desai
Balances • Types • Micro balances • Top Loaders • Analytical Balances • Floor Scales
Validation • Pre-purchase meeting with QA, users, and a member of Metrology • Discuss the user requirements and the suitability of the proposed balance to be purchased. • The Lab Strategy form is completed once the equipment arrives to determinewhether it will be used for GXP purposes. • If the unit is to be validated, protocols are drafted, reviewed and approved by the user and the validation team. Example of protocols include the Installation Qualification and Operational Qualification. • Additional task include: • The calibration/maintenance requirements to be performed periodically. • Users and Metrology will create or revise any SOPs (use/calibration). • Once all of the pertinent documents and tasks are executed, reviewed, and approved (meets all specifications), the balance may be release for GXP laboratory purposes.
Calibration • All of the calibration requirements (determined during the validation phase) are setup in the validated software database referred to as Calibration Manager. • The database information • Includes the location of the equipment, user department, cost of unit, history (calibration, unscheduled repairs, etc.), scheduling, and calibration data references. • Calibration scheduling may include monthly, quarterly, and semiannual checks.
How its done? • The monthly checks may require minimum and maximum weight checks. • The monthly uncertainty is checked using the min weights. • Additional maintenance is done as required. • The semiannual calibration checks may involve the use of an approved outside vendor to perform calibrations and maintenance • Includes lubing and thorough cleaning.
Accuracy • Accuracy Checks are done using calibrated Class 1 weights. • During Calibration • Min/Max +/- 0.1 % (measured vs. certified); Uncertainty +/- 0.1 % (repeat of 10 measurements of the min) • Daily Activities • Min +/- 0.1 % (measured vs. certified)
Weights • The weights are calibrated by a certified vendor. • Solvay sends their weights to Heusser Neweigh.
Daily Use • Users perform daily checks using the minimum weight accepted on the balance. This is required before the balance may be used for any GXP purposes that day. • The daily accuracy specification is the certified minimum weight vs. the measured minimum weight +/- 0.1 % of the weight. • The daily checks along with any other entries such as the material to be weighed are recorded in the logbook. • The logbook is cross referenced with the lab notebook.
Micropipettes • Micropipettes are used to transfer small liquid volumes. • It is used for more accurate and precise measurements of volumes smaller than 1ml. • It was invented in 1957 by Heinrich Schnitger in Germany.
Micropipettes • Micropipettes have 3 positions: • Rest position. • First stop. • Second stop. • How to use it : • Set volume. • Attach disposable tip. • Depress the plunger to 1st stop. • Immerse tip in sample and Draw up sample. • Withdraw the tip. • Dispense the sample by pushing the plunger to the 2nd stop. • Withdraw the pipette and release the plunger. • Discard the tip
Accuracy and precision • Optimal range: 35% - 100% of volume • Use a correct immersion angle. Pipette perpendicular to solution. • Withdraw tip slowly and smoothly from liquid. • Maintain controlled aspiration rates. Don’t let plunger snap back. • Be consistent with pipetting rhythm, pressure on the plunger and speed.
Micro Pipettes • The pipettes are purchased based on the users preference. • Solvay Pharmaceuticals typically purchases from Eppendorf. • Standard pipettes are not validated (IQ/OQ) • Calibrated on a semiannual basis
Calibration • Solvay’s calibration is currently done by Troemner • Troemner has been audited and deemed as an acceptable vendor to calibrate them. • They do “As Found” (when received or as is) and “As Left” (after adjustments/maintenance).
References: • http://us.mt.com/home • http://en.wikipedia.org/wiki/Micropipette • Solvay Pharmaceuticals