Balances and
Micropipettes
By: Paola Restrepo and Ankita
Desai
Balances
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Types
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Micro balances
Top Loaders
Analytical Balances
Floor Scales
Validation
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Pre-purchase meeting with QA, users, and a member of Metrology
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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
determine whether 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.
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Additional task include:
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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
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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
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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?
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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
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Includes lubing and thorough cleaning.
Accuracy
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Accuracy Checks are done using calibrated
Class 1 weights.
During Calibration
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Min/Max +/- 0.1 % (measured vs. certified);
Uncertainty +/- 0.1 % (repeat of 10
measurements of the min)
Daily Activities
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Min +/- 0.1 % (measured vs. certified)
Weights
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The weights are calibrated by a certified
vendor.
Solvay sends their weights to Heusser
Neweigh.
Daily Use
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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
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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
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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
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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
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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
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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:
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http://us.mt.com/home
http://en.wikipedia.org/wiki/Micropipette
Solvay Pharmaceuticals