Single channel electronic pipette

Choosing between mechanical pipettes and electronic pipettes may seem quite daunting but at CAPP we make the choice easy. CAPP mechanical pipettes are a great option for budget-restricted laboratories as they maximize savings without compromising scientific output. Mechanical pipettes are faster to set up and make it easy to transfer small volumes with ease. Electronic pipettes are great for speeding up multi-sample liquid transfers. With automated dispensing and programmable features, CAPP electronic pipettes increase efficiency by optimizing pipetting workflows. Click the links to learn more about the different mechanical pipettes and electronic pipettes that are available at CAPP.

Pipetting technique is a term that is used to refer to the full scope of a user's interactions with a pipette as they conduct their experiments. As would be expected, some practices are termed proper pipetting technique and help the user maintain a high level of accuracy and precision in their volume transfers. Bad pipetting technique, on the contrary, may introduce error and produce inaccurate volume transfers that would be difficult to replicate. Proper pipette technique depends on a range of factors with the most significant being the user and their instruments of choice. The user-dependent aspects of proper pipette technique are a learned skill. We wrote this blog post to provide some helpful tips for users to improve their micropipette technique. With diligent study and careful practice, it will become easy for most scientists and lab technicians to produce reliable results from their volume transfers. As for the equipment-dependent aspects of proper pipetting technique, choosing high-quality pipettes and pipette tips will significantly improve pipetting technique.

Calculating percent error in pipetting is a simple process that is easy to accomplish in a few steps. As most modern pipettes such as the CAPPMaestro single channel pipette feature a manufacturer specified uncertainty value, this value is what you will reference for your calculations. The uncertainty is also referred to as the error of the pipette and as such percent error may also be referred to as percent uncertainty. The formula for calculating percent error is illustrated below. For example, the percent error for a 1000 µL pipette with an uncertainty of 0.8 would be 0.08%.

The error of a pipette is an abstract concept that cannot be determined in real world pipetting environments. It is defined as the difference between the measured value and the true value. If a pipette user measures 1002 µL with their automatic pipette when they intend to measure 1000 µL, the error would be 2 µL. However, as it is not possible to accurately determine the error of a pipette manufacturers prefer to use the concept of uncertainty to approximate pipette error. Uncertainty is a probabilistic value that gives a degree of confidence that the true value of a measurement lies within the uncertainty range. Manufacturers often publish the uncertainty of a pipette on the actual device to guide users on the error of the pipette. 

Systematic error can be linked to the pipette (innate) or the user. The best way to avoid innate systematic error is to purchase premium quality pipettes from reputable manufacturers. Additionally, regular servicing of your pipettes helps minimize systematic error. User-centric systematic error can be avoided by routine testing and improving one’s pipetting technique. You can test your own systematic error by pipetting ten replicates of a fixed volume of distilled water on a calibrated balance. Calculate the relative standard deviation (standard deviation expressed as a percentage of the mean) of the ten values to get your pipetting error. With this knowledge, you can then implement good pipetting technique and frequently test if your systematic error is reducing. Additional practices such as storing pipettes in a vertical position and using filter tips when transferring corrosive liquids further reduce the incidence of systematic error in your laboratory. 

One of the most common pipette handling errors is pipetting too fast. Although this may seem desirable for increased efficiency, it will result in inaccuracies in sample loading and offloading. Slowing down and applying constant pressure on the plunger reduces errors. Another error typical of inexperienced users is pipetting at an angle. Micropipettes work best when used at a near-vertical angle for the forces of physics to do their work. New and old users alike often fail to pay attention to their choice of tips. Only use manufacturer recommended tips such as the ExpellPlus range from CAPP, as these offer the greatest compatibility with your pipettes. Lastly, scientists may forget to prewet their tips before liquid transfer. This may cause evaporative losses of liquid during aspiration while also reducing pipetting accuracy.