In some situations (note the following exception), it is only necessary to verify the accuracy of one channel. The exception being critical experiments where regulatory agencies mandate that all channels must be gravimetrically evaluated (using correct equipment and procedures) and accuracy and precision properly documented.
All channels in a multichannel pipette are driven by a single plunger rod that is connected to a push bar rod that is attached to 8-12 piston assemblies. The movement of the plunger rod in aspiration and dispensing cycles expels the same and equal quantity of air to aspirate the same and equal volume of liquid. All channels must be leak-free and the sealing components in the liquid end must be in sound condition. Make sure all channels are airtight (use visual gravity method in the absence of a leak tester). Be sure to change the sealing components, if needed.
To check for leaks:
- Load tips onto the pipette
- Set the volume to 100% and aspirate water into all 8-12 tips
- Withdraw the pipette tips from the water and wait 15 seconds to see if any visible leaks form
- Be sure to verify the water level from channel-to-channel.
Verify the accuracy of any one channel with the balance of proper sensitivity [adjust the 10% volume with the tool, if needed (tool varies with pipette model)] to make sure the accuracy is within the specified tolerance. Calibration adjustments should always be made at the 10% volume for accuracy and precision, as per most manufacturer’s guidelines.
Printable Calibration Log
Printable Calibration Stickers (for use with Avery 5960 labels)
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Non-Linear Volume Readings – When Should A Calibration Adjustment Be Made?
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