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Measuring the Efficacy of Liquid Handling Processes

Quality assurance in regards to liquid handling processes is a standard requirement.  There is the simple expectation that liquid handling processes are both thorough and exacting in order to make sure that the data provided is of the necessary quality.  

It is important to note that when we speak of volumetric accuracy, we define the term “accuracy.”  In this case, “accuracy” describes the deviation of the actual from the targeted dispensing volume. Similarly, it is also necessary to define “precision” – essentially, highly consistent results.

What tools, then, are available to scientists to support their need for quality assurance in regards to measuring the efficacy of liquid handling processes?

Tools for Quality Assurance

There are several available with these 3 being the most widely used: 

  • Gravimetric
  • Fluorometric
  • Photometric

Each of those methods have their own advantages and disadvantages which are summarized in Table A below.

GravimetricFluorometricPhotometric
Uses an analytical balance to weigh liquid volumesAdds a dye to a liquid which is then illuminated at a specific wavelength which in turn absorbs light energy that then emits at a different wavelengthMeasures the concentration of compounds in a solution by determining the absorbance of wavelengths of light. Uses a dye and a plate reader to analyze results. It takes the difference between the amount of light transmitted and the light generated from the source.

Accuracy at high volumes

Readily available balances

Traceability through weight sets

Does not use any dyes or additives

Good for low volume measurements

Precision

Permits for testing in the actual labware used

Insensitive to the environment

Precision

Permits for testing in the actual labware used
Inaccurate at low volume. Influenced by factors such as evaporation and so errors can occur as volumes become smaller

Requires specialized balances that are fairly delicate

Time consuming process. For example, on a multi-channel pipette you can only do 1 channel at a time. 

Room for errors because it uses a balance to weigh liquid volumes.  The weight is converted to a mass and then to a volume. Issue is compounded if the density of the fluid dispensed is unknown (and even if it is known there is still room for error).
Fluorescent dyes can be expensive

Poor traceability

Limited accuracy

Needs a plate reader to obtain results

Adding a dye can change the physical characteristics of the liquid

Choosing the right dye can be tricky
Limited accuracy

Traceability depends on preparation

Needs a plate reader to obtain results

Adding a dye can change the physical characteristics of the liquid

Choosing the right dye can be tricky
Table A

As noted, all of the methods have their pros and their cons. 

Is There A Simpler Method That Can Also Provide The Needed Quality Assurance?

Yes! 

The LabBee Checkit Go is a simple, stand-alone, disposable cartridge that allows you to check the accuracy of your liquid handling robot or multi-channel pipette in just seconds. No additional equipment is required.

LabBee Checkit Go

LabBee Checkit Go Benefits

The LabBee Checkit Go cartridge has a number of advantages:

  1. Simple to use and no training is required
  2. Fast and accurate. Measurements are guaranteed to be accurate within 2% and it also directly measures the volume dispensed compared to other indirect methods such as the gravimetric method.  It can measure dispensed volumes of up to 8 channels in under 10 seconds.
  3. It works with multi-channel pipettes and Automated Liquid Handlers. 
  4. There are no annual maintenance costs and it is the fraction of the cost of unnecessary calibration
  5. Facilitates the measurement of solutions with different viscosities

For more details on how the LabBee Checkit Go system works, please contact us for more details.  We would love to hear from you and see how we can help.

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