Pipettes and Pipette Tips by Sartorius

To achieve the highest level of accuracy, you should choose the smallest volume pipette capable of handling the volume in question. This is important because pipette is most accurate at nominal (maximum) volume. It is a well-recognized fact that even slight muscle fatigue reduces the output when performing work that requires precision. Therefore, in order to maintain the performance, pipettes which require high forces should be avoided. Moreover, heavy pipettes fatigue the user, selecting an ergonomic pipette allows precise operation. Electronic pipettes can be considered when number of samples is high or when reducing variance in pipetting is important. A multichannel pipette can significantly speed up working with 96 and 384 well plates.

There is two principles of how pipettes work, air displacement and positive displacement. The majority of pipettes used in laboratories work according to air displacement principle due to their wide applicability and lower costs of consumables. Positive displacement pipettes are sometimes used with problematic liquids, but air displacement pipettes can be used as well with correct techniques. An electronic pipette can eliminate a lot of the variance from pipetting and also variance between users. With an electronic pipette the piston movement is controlled automatically regardless of the user.

Different pipettes can fit different application, for example when working only with few samples a mechanical pipette is good choice, but when working with 96 microwell plates multichannel pipette is a better option. But in general lighter pipettes are better ergonomically, electronic pipettes can reduce the variance, and using tips and pipettes from the same manufacturer creates the most accurate system. Remember that choosing the right tip is as important as choosing the right pipette!

Pipette will be accurate when you use correct pipetting technique considering liquid properties, use proper fitting tips, and keep it well maintained and calibrated.

Pipettes transfer liquid using piston system whereas burettes are graduated glass tubes. Pipettes are used when moving known amount of liquid and burettes are often used to determine unknown amounts.

Pipettes are precision measuring instruments designed to reliably and repeatably transfer small amounts of liquid. Well maintained pipettes will last for a long time.

People often use calibration stickers with the last calibration date. Also you should have a calibration certificate with a date stating that the pipette has passed calibration.

Pipettes are used to transfer accurately small amounts of liquid. Disposable pipette tips are used in conjunction with pipettes to hold the liquid.

Pipettes are often calibrated according to ISO 8655-2 in an ISO 17025 accredited calibration laboratory by trained service personnel. The technician tests and adjusts the pipettes, usually in a 3-point calibration (100% - 50% - 10% of nominal volume). Commonly a balance with moisture trap and distilled water are used, along with environmentally controlled room.

There are two main factors, accuracy and precision. Accuracy describes the ability of an instrument to give responses close to the true value. It expresses the difference between the mean volume of actual measurements and the true value. Precision describes the ability to produce closely similar measurements. It tells how close a set of repetitive measurements are to each another. 

1. Plan the pipetting steps, especially with applications where contamination can be an issue.
2. Select a pipette that covers the volume you desire to transfer.
3. Select tips that fit the pipette.
4. Adjust and lock the volume to prevent accidental volume changes.
5. Select technique according to liquid.
6. Operate plunger slowly and smoothly, or with an electronic pipette select correct speed.
7. Remember good ergonomics, to protect yourself from accumulating strain.
8. Store pipettes in stand and make sure they are maintained and calibrated regularly.

Pipettes with air displacement principle have a piston-cylinder -combination which manipulates an air column between the piston and liquid. Pressure changes in air column move the liquid in and out.

According to Oxford dictionary pipette and pipet are synonyms.

Check that the position of the multichannel pipette lower part can be rotated 360 degrees to ensure that pipetting can be performed ergonomically. Make sure that the multichannel pipette provides fast, secure, and simultaneous tip loading for all tips. It should be possible to mount the tips evenly without excessive force. Check also that the tips can be easily ejected.

Professional training is a very good option to improve pipetting skills. Especially when working with viscous, volatile, or liquids with low surface tension proper technique will increase the quality of results significantly. Ask your pipette provider if they offer training courses.

In addition to being able to pipette more accurately and precisely, proper training can save you time and promotes ergonomical working habits. See our training offering at http://technology.online.housing.mtoliet.com/en/knowledge/trainings/pipetting-academy

Pipettes can be used with many different techniques, especially the electronic pipettes. Choose the technique according to the liquid you are pipetting. For more infromation ask your pipette provider for training. See our Pipetting Academy offering at http://technology.online.housing.mtoliet.com/en/knowledge/trainings/pipetting-academy

1. Winding above or below the marked volume range.
2. Dropping or hitting, or othervice physically damaging pipette.
3. Using tips that do not properly fit to the pipette or that that the pipette is not calibrated for.
4. Using wrong pipetting technique, especially with viscous or volatile liquids.
5. Forgetting to calibrate your pipettes, calibration is the only way to ensure pipette will deliver reliable results.

A standard in most laboratories, micropipettes are instruments used to accurately and repeatably transfer small amounts of liquids in the microliter range (µL).  As standard pipettes usually start at 1 mL, micropipettes are used when minute amounts need to be measured with accuracy.

Automatic pipettes allow you to choose the volume before aspiration and dispensing, meaning they "automatically" transfer the correct amount.  Automatic pipettes are beneficial when tasks require a fixed amount of liquid to be transferred repeatedly.

Volumetric pipettes: Volumetric pipettes are typically made of plastic or glass and have graduation marks. Their volumes generally range between 1mL - 100mL. Volumetric pipettes rely on users for measurement of volume and require a separate device for aspiration and dispensing - such as the Midi Plus pipette controller.

Discover our Midi Plus Controller
 

Mechanical / manual pipettes: A workhorse of most laboratories and widely used in various applications. Manual pipettes aspirate and dispense liquid with piston system driving air cushions. These pipettes always use disposable pipette tips. User is able to set volume and use a plunger to aspirate and dispense liquid. 

Discover our Mechanical Pipettes
 

Electronic pipette: The basic operating principle of electronic pipettes is the same as with mechanical, but all actions are handled by an electronic system inside. The user only has to press a button to start aspiration, liquid dispensing or tip ejection. Electronic pipettes typically reduce human variance, improving accuracy and reproducibility.

Discover our Electronic Pipettes
 

Automation pipettes: Automation pipettes are similar to electronic. The key difference is they are controlled by automation software and typically have mounting points for automation instead of handles for humans. 

Dispenser / positive displacement pipettes: Positive displacement pipettes rely on syringe-like consumables for aspiration and dispensing. Available in mechanical and electronic form. 

Discover our rLINE^® Dispenser