Definition
A multichannel pipette is a precision instrument used in laboratory liquid manipulation that allows operators to process multiple samples simultaneously, typically with specifications such as 8, 12, or 16 channels. The device can quickly and accurately draw, distribute and transfer liquids through disposable suction tips, and is widely used in experiments that require high-throughput processing.
Principle
Multichannel pipettes work based on air displacement or forward displacement mechanisms. In the air displacement type, the piston moves in a closed cylinder and drives the liquid to suck in or discharge the suction tip through the compression and expansion of the air cushion. The pipetting volume V can be roughly described by the relationship between the cross-sectional area of the cylinder A and the piston displacement ΔL: V = A × ΔL. The forward displacement type uses a piston in direct contact with the liquid and is suitable for high viscosity or volatile liquids. The multi-channel design means that multiple independent piston-cylinder systems are integrated in parallel, controlled by a common operating mechanism, ensuring that each channel is synchronized.
Measurement method
The performance evaluation of multichannel pipettes is usually carried out according to international standards such as ISO 8655. Key measurement parameters include accuracy and precision. An analytical balance is used to measure the mass of pure water by weighing the pipette and convert the density to volume based on the water temperature check. Each channel requires multiple test points (e.g., minimum, middle, and maximum volume) to be selected within the range for repeated measurements. Accuracy reflects the proximity of the indicated value to the actual volume, while precision reflects the consistency of repeated operations. Measurements should be taken in a constant temperature and humidity environment to reduce the impact of environmental fluctuations.
Influencing factors
The performance of multichannel pipettes is affected by a variety of factors. Operating technology is key, including tip fitting, assembly tightness, and control of suction and discharge angles and speeds. Liquid properties such as density, viscosity, and vapor pressure can affect the results of air displacement pipetting. Environmental conditions such as temperature, air pressure, and humidity can alter air cushion behavior. The condition of the instrument, such as piston tightness, spring fatigue, and routine calibration maintenance, also directly determines long-term reliability. In addition, the uniformity between channels of multichannel pipettes is a unique consideration and needs to be verified regularly.
Application:
Multichannel pipettes play an important role in high-throughput experiments in a wide range of fields. In life science research, it is commonly used for microplate manipulation, such as nucleic acid extraction, PCR system construction, cell culture seeding, and enzyme-linked immunosorbent assays. In the field of food testing, it can be used for sample preparation and preparation of additive standard curves. In environmental monitoring, the addition of standards and reagents in water quality analysis can be efficiently completed. Its design significantly increases the throughput of sample processing, reduces repetition time, and helps reduce errors introduced by the number of operations.
Selection
Choosing the right multichannel pipette requires a comprehensive consideration of your experimental needs. The number of channels should match the commonly used microplate format, e.g., a 96-well plate for an 8-channel or 12-channel pipette. The range of measurement should cover the volume of liquid that is routinely treated in the experiment. For special liquids, such as high viscosity or volatile reagents, a model with a forward displacement principle may be required. Ergonomic design is about comfort for long periods of use, and the adjustable finger rest and moderate handling force are worth paying attention to. Instrument calibration and after-sales service support are practical for ensuring long-term measurement reliability. Users should make comprehensive judgments based on their routine tasks, sample throughput, and liquid characteristics.