Validation Pipette

Abstract

We have implemented a simple, inexpensive and rapid procedure for the validation and verification of the performance of pipettes mounted on automatic liquid handlers (ALH) as required for laboratories accredited under ISO 17025. A serial dilution of six or more was prepared. seven OrangeG passes in quadruplicate in a 96-well flat-bottom microtiter plate, manually using calibrated pipettes. Each liquid handler pipet (1-8) dispensed a selected volume (1-200 µL) of OrangeG eight times into the wells of the microtiter plate.

All wells contained a total of 200 µl of liquid. The absorbance was read and the volume dispensed from each pipette was calculated based on a volume and absorbance plot of a known set of OrangeG dilutions. Finally, the percentage of inaccuracy (% d) and imprecision (% CV) of each pipette were calculated. Using predefined acceptance criteria, each pipette passed or failed. Defective pipettes were repaired or volume deviation compensated by applying a calibration curve in the liquid handling software.

We have implemented the procedure on one Sias Xantus, one MWGt TheONYX, four Tecan Freedom EVOs, one Biomek NX Span-8, and four Biomek 3000 robots, and the methods are freely available. In conclusion, we have put in place a simple, inexpensive and fast solution for the continuous validation of ALHs used for accredited work according to ISO 17025. The method is easy to use for aqueous solutions but requires a spectrophotometer that can read plates of microtiter.

Validation (Qualification)

For the conversion of a mass value to a volumetric value, the density of the distilled water to be used must be determined. This requires a mathematical scheme that has the temperature of distilled water and barometric pressure as its parameters. Therefore, validation when using the gravimetric method requires 1) a balance that measures the mass value of distilled water, 2) a thermometer that measures the temperature of the distilled water, and 3) a barometer. However, the variation in the measurement results due to the barometric pressure fluctuation is negligible. In practice, it will suffice to establish and use a representative value (fixed value) of the location, and no new equipment needs to be controlled.

Consequently, the validation of pipette precision testers requires confirmation of the qualifications of the
balance and thermometer. Formats (samples) for these ratings are available upon request and users may perform the validation themselves. See the document titled “The Uncertainty of Volume Calibration Using A&D Pipet Accuracy Testers ”for our technical considerations of volume calibration uncertainty.

  1. Reduce risk, avoid rework

Verifying the performance of a pipette before working with valuable samples and reagents saves time and money. In less than 60 seconds, you can know that your pipette is aspirating and dispensing correctly. In regulated environments, avoid costly and time-consuming research that an out-of-tolerance pipette can lead to.

2. Reliable pipette verification in seconds

With SmartCheck ™, pipet verification is simple:

  • Adjust the pipet to its nominal volume, then, using deionized water, pipet that volume into the SmartCheck container.
  • After automatically detecting the volume, SmartCheck prompts you to dispense the same volume three more times.
  • SmartCheck runs a series of calculations and then clearly indicates Pass or Fail.

3. Check any brand of pipette … instantly!

Use SmartCheck to verify the performance of any brand of pipette that dispenses volumes between 10 and 1000 μL. Also, check the individual channels of the multichannel pipettes. It’s simple: dispense deionized water into the liquid chamber and SmartCheck automatically detects the test volume, then prompts you to dispense the same volume three times more. From start to finish, SmartCheck offers a pass / fail result in less than 60 seconds. SmartCheck is also perfect for training and improving pipetting techniques.

4. How does SmartCheck work?

SmartCheck is not only fast, it is the only ISO 8655-based automatic pipette verification tool available. SmartCheck takes volumetric measurements using the gravimetric method and calculates the random and systematic error based on four measurements.

It then determines the uncertainty of measurement of the delivered volume in percentages, comparing it to the pipetting tolerance in percentages, yielding a rapid pass / fail statement for the instrument and user within 60 seconds.

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