The most commonly used piece of laboratory equipment in any laboratory setting is the pipette, which has a long history of use as well as ongoing advances in design, ergonomics and usability.
The goal of pipetting is to ensure maximum accuracy and repeatability when transferring fluids. Research and development labs in the chemicals, foods, materials, and paints industries use pipettes routinely. However, it is in the life sciences that the greatest number of pipettes and related supplies are found.
The type of analysis you are performing, the physical properties of the liquid, and the volume range required will determine which pipette and tip you should use—either a Positive Displacement Pipette or an Air Displacement Pipette. Air displacement pipettes are commonly used for aqueous samples and general lab work. Positive displacement pipettes are commonly used for heavy liquids or ones that are too viscous to be displaced accurately by air, as well as dense, volatile, radioactive, or corrosive samples.
Today’s pipettes often feature digital controls, allowing for the high precision measurement of extremely low volumes of liquids that is absolutely essential in the modern laboratory environment.
While pipettes are handheld, their delivery mechanism may be manual or electronic. Manual delivery refers to the operator’s thumb depressing or releasing a piston to deliver or withdraw liquid. Electronic pipettes are considered a halfway point between manual and robotic liquid handling and offer high reproducibility, a reduction in the force necessary for operation, and multi-functionality in dispensing techniques. Repeating electronic air displacement pipettes are used for repetitive serial pipetting. They are commonly used in applications such as biochemistry, immunology and microbiology where samples need to be rapidly dispensed in the same volumes.
Pipettes are sold in two basic formats: fixed volume, which always dispenses the same quantity of fluid; and adjustable volume, which delivers a range of volumes. Adjustable pipettes are accurate from about 10 percent up to 100 percent of the volume range. Single-channel pipettes use one tip at a time, whereas multichannel devices hold multiple tips for simultaneously delivering fluids to multiple locations. Biologists who work with microtiter plates, immunoassays or polymerase chain reactions will probably be interested in multichannel pipettes.
Type(s) of pipettes respondents are currently using or plan to purchase.
|Using||Plan to Purchase|
|Manual: Fixed volume||38%||3%|
|Electronic: Fixed volume||6%||2%|
Among all of the factors impacting the performance of a pipette, the most important are the skill and expertise of the user. A high-quality pipette in the hand of an untrained operator is an unreliable instrument and will generate inaccurate results. Please turn to page XXX for 10 tips to improve your pipetting technique.
Close to 60 percent of respondents attribute human error as the major source of problems in their pipette performance.
|Liquids stick to tip||32%|
|Immersed tips carry over liquid||19%|
|Pipettes take up more liquid||14%|
|Surface tension reduces accuracy||21%|
The pattern of use varies from person to person. Are pipettes used occasionally or frequently? For brief periods or for prolonged periods in the lab? Heavy use means increased risk of Repetitive Strain Injury (RSI), therefore it is important to find a pipette that is right for the user and the task.
Amount of time spent per day by the individual(s) in their lab working with a pipette. One out of five respondents spend over three hours a day using a pipette
|Less than 1 hour||32%|
|1 - 2 hours||30%|
|2 - 3 hours||16%|
|over 3 hours||22%|
There are many different features of a pipette to take into consideration before making your purchase, including ergonomics, low force, fitting, ease of use, reliability, accuracy, and precision.
Consistent performance and accuracy of product are the two major factors that play into pipette purchases— users must know that they’re dispensing the right volume. Like other laboratory devices, pipettes must be calibrated and validated for the type of work they do, particularly in regulated industries. Pharmaceutical and biotech work, for example, is done under Good Laboratory Practices (GLP), which is a regulatory designation. Many end users today choose motorized electronic pipettes for GLP work. The devices record volumes and number of cycles and can even provide out-of-specification warnings.
Pipetting is no different than any other excessive repetitive motion that can harm the user, hence ergonomics is a huge issue. As a result, most vendors have worked on the design and use of the pipette, making them far more ergonomic.
Try before you buy. Many pipette suppliers will visit customers onsite to give pipette demonstrations or send out loan pipettes for a trial period, allowing you to assess them for yourself.
Top ten factors/features that influence the decision-making process
|Consistent performance and accuracy of product||100%|
|Durability of product||98%|
|Low maintenance / easy to clean||97%|
|Availability of tips and accessories||95%|
|Designed to permit recalibration||90%|
|Service and support||82%|
For more information on pipettes, visit www.labmanager.com/pipettes
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