Best practices dictate that pipettes undergo preventive maintenance and calibration at least once per year. Calibration involves dispensing set volumes of a liquid, usually water, into the weighing pan of a calibrated balance. Service personnel correct for temperature, humidity, and atmospheric pressure, and then compare the expected weight to the actual weight. Among the numerous service options are end-user, in-house instrument service groups, third-party maintenance organizations, and the original manufacturer. All have their benefits and drawbacks.
Small, independent service providers are numerous and focus on academic customers within a relatively small geographic area. Regardless of their size, service organizations work either through “depot” arrangements (pipettes are boxed and shipped to the servicer) or on-site. Servicers generally do not require a minimum number of devices for depot service, but all have requirements for on-site service.
The fly in the ointment for thirdparty servicing in general is the electronic pipette. Although electronic pipettes comprise just 7–8 percent of all pipettes in use today, electronic models are the fastestgrowing segment of pipette products. Multichannel pipettes make up approximately 20 percent of sales, while standard, single-channel piston and o-ring devices comprise about 70 percent of the market.
“Most service providers can easily service standard pipettes,” says Joe Fredette, product director for liquid handling and consumables at Thermo Fisher Scientific (Hudson, NH). Thermo Fisher and other manufacturers provide calibration and service instructions freely to users who choose to service their own pipettes. But electronic pipettes, which contain printed circuit boards and onboard logic for storing methods, can be challenging. “They require a professional service provider,” Mr. Fredette adds.
Users who service their own pipettes have several options. A&D Weighing (San Jose, CA) sells a dedicated balance for pipette testing, as well as accessories for servicing pipettes that work with their standard scales. The main components are software and an evaporation trap to ensure that very low liquid volumes do not evaporate or pick up moisture from the air. A&D also sells a leak tester that induces a vacuum to detect leaks in pipette seals, pistons, or o-rings.
“Any organization can perform its own calibration and routine service. Whether they are actually interested [in doing so] is another matter,” observes Markus Jansons, weighing products manager at A&D. “You need to have a relatively large number of pipettes to justify dedicating equipment and personnel to pipette calibration.”
Remember, though, that pipetting is susceptible to end-user technique, and what holds for pipetting in general is doubly true for pipette calibration.
Due to issues of time and convenience, demand is rising for servicing pipettes on the customers’ premises, but hard-core metrologists protest that control over environmental conditions is impossible. Rigorous depot calibrations take place in environmentally controlled rooms. “Saying that you’re not getting a true calibration is a bit hard-line,” says Mr. Fredette. “But in fact, what many users receive on-site is not a calibration, but a service check.”
- Electronic operation reduces the risk of repetitive strain injury (RSI)
- Cover-volume of two mechanical pipettes
- Single-channel models cover volume ranges of 0.2 to 5000 μl
- Multichannel models cover volume ranges of 0.2 to 1200 μl
- Offers relief for workers who experience repetitive stress injuries caused or exacerbated by traditional pipetting
- Keeps the hand in the neutral position (as recommended by ergonomic experts)
- Available in several models, including adjustable-volume, electronic and macrovolume electronic
- Also available in left-handed models
96-channel Electronic Pipette
- Features proprietary Touch Wheel™ interface for easily programming various pipetting modes including repeat dispense, serial dilute and sample dilute
- Four pipetting heads with pipetting volumes up to 12.5 μl, 125 μl, 300 μl or 1250 μl are available
- Compatible with VIAFLO GripTips, which provide a perfect seal and won’t fall off during use
- Provides light-touch dispensing and tip ejection for superior ergonomic performance and reliability
- Provides innovative tip interface
- Delivers consistent liquid dispensing while maintaining a secure seal
- Hydrophobic inner surface prevents liquid retention
Thermo Fisher Scientific