1. What are the main causes of/solutions to the problem of pipette leaks?

a.  Tip holder is scratched or damaged - Replace Pipette Tip holder.

b.  Vapour pressure from organic solvents - When an organic solvent is used with an air-displacement pipette, leaks may occur.  These leaks are caused by the difference between the vapour pressure of the solvent and pressure of the air cushion between the piston and the sample. The use of  a positive-displacement pipette can combat this.

c.  Incorrect attachment of the tip - Always use manufacturers recommended tips. Make sure that the tip seals with the pipette shaft by pushing upward on the tip-ejector to make sure it is positioned properly. If not then another brand of tips may have to be used. Please note that no one pipette tip brand can fit all pipettes. Alternatively clean the tip holder with alcohol. If this does not rectify the problem, or if the tip holder is worn or has been chemically attacked, order a new part.
d. There is a foreign object (i.e. dirt, grit, crystallized material) between the piston, o-ring, and nose cone) - Clean and grease tip cone module and o-ring; attach new tip. (Note that some pipettes do not need grease on the piston for correct operation. These pipettes work by a ‘Dry Seal’ Technology and any introduction of grease onto the piston can irreversibly damage the pipette).
e.  The o-ring has been damaged or warped - Change the o-ring.
2. Why is the manufacturing quality of a tip so important? 

Tip quality can affect pipetting results in a number of ways: 

• Hydrophobic qualities - if a tip’s hydrophobic properties are diminished, it could retain liquid inside, or even retain a drop of measured liquid on the outer surface.
• Poor quality tips may have burrs or plastic flash which do not allow the smooth release of all liquid within the tips – some of the measured volume may be trapped at the end of the tip.
• Non-concentric tip openings to the end of the tip affect the dispensing of the contents. Some liquid may adhere due to changes in surface properties.
• Tip straightness affects the dynamics of the air displacement.

3. Should I pre-wet tips?   
Reference documents (EN ISO 8655-6:2002 Section 7.2.5) recommend that prior to use and calibration, each pipette tip should be pre-wet in the sample to be used. This greatly increases the accuracy and precision of your work. However refer to the pipette user manual before use.
4. How can I prevent piston corrosion?
Avoiding accidental aspiration of liquid into the pipette shaft prevents piston corrosion and also remember never leave a pipettes on its side with liquid still in the tip.
However if liquid is accidentally aspirated into the barrel of the pipette the piston should be cleaned with ethyl alcohol, IMS or IPA (Please refer to the user manual for the pipette prior to this) are also suitable and a soft tissue.  Take care to avoid shocks or scratches to the piston as this will change the dispensed and aspirated volume.
5. Should I rinse out the tip when I am dispensing?   
No. Pipettes are calibrated to deliver (TD) not to contain (TC). Rinsing out will change the amount of calibrated liquid being dispensed. 
6. My pipette is not aspirating. What could be the problem?   
Verify that the nozzle and/or extender are firmly tightened. Then rule out that the liquid blocking nozzle has not become wet by changing the nozzle.
7. How often do I need to replace seals?  
The seals should not require changing unless the pipette has been used with chemicals that are harmful to or negatively affect rubber or the pipette is leaking.
8. How do I know it is time to replace seals?   
Precision and accuracy are not within specifications, and technique and environment are not a factor.
The pipette’s plunger is not moving freely.
The pipette leaks and this condition is not related to tips.

9. What do I do if the operating rod becomes stuck?
When the push-button is depressed, the action should be smooth. If this is not the case, the operating rod maybe damaged or bent (this can occur when a pipette is dropped). The rod needs to be replaced and the pipette should be recalibrated.

10. What is MTBF?
MTBF is an acronym for Mean Time Before Failure. In relation to pipettes it is the average rate at which failures can be expected to occur. The MTBF for a group of pipettes is determined by tracking the group and observing how long it takes each one to fail. Governing factors in its determination are the material used in the pipettes, storage & handling, the frequency of usage and the period between preventative maintenance procedures.

11. What are Manufacturer Specifications?
These are specifications for accuracy and precision and are established by the manufacturer of a pipette. They guarantee the performance of all pipettes of a given brand and a given model at a certain volume setting. However, they are unrealistic in relation to everyday pipette use. They are established under very tightly controlled environmental conditions using expert technicians and new pipettes.
Some manufacturers provide what are known as ‘Field Specifications’. These are a guide for defining maximum permissible errors for pipettes that are in daily use in a working laboratory and which are more realistic of everyday pipette use.

12. What is Repetitive Strain Injury?
Repetitive Strain Injury (RSI) is what is caused by the repeated carrying out of the same task. Its relation to the use of a pipette is clear. The repetitive plunging and deplunging procedure results in this injury.

13. How can I combat RSI?
Preventing Injuries from pipetting, like other types of ergonomic injuries, can be reduced or eliminated through a few simple steps. Reduce pipetting tasks and review protocols to remove extra steps or unnecessary pipetting. Pipetting more than one hour a day increases the risk of injury, so rotate tasks, if possible. Take breaks every 20-30 minutes if you pipette for long periods. Hold the pipette loosely and relax hands periodically. Textured gloves may help. Use chairs with adjustable backrests and seats and position the chair to support your back for work that requires leaning forward. Use adjustable foot-rests, as foot rings on stools may not be adequate. Train on safe work procedures and recognise the early symptoms of injury. Organise your workstation and position frequently used items to minimise reaching or leaning, use a top disposal container that is lower than the container into which you're pipetting, post protocols straight ahead at eye level to prevent bending or twisting, and pad hard edges or surfaces you rest against. Use as little force as possible when putting on tips or pressing the plunger and discarding tips.
14. How often should I verify calibration?   

Calibration verification should be performed routinely at least every three months. In addition, calibration verification should be performed for any of the following reasons:

• Maintenance such as seal replacement has been performed.
• Quality control sampling shows a change in results.
• Pipette is dropped or damaged.
• The number of times a pipette is calibrated per year depends on the number of times the pipette is used and the quality standards of the laboratory. EN ISO 8655-1:2002 Section 7.3 recommends that pipettes receive an evaluation at least on a quarterly basis.

 ‘The main objective of pipettes in a Quality System is to ensure that measurements are made with the intended accuracy. Very often error limits are taken from the manufacturer’s specifications, while far less accuracy is required to perform the work. If these limits are not easily obtained, or vary, another option is to set the limits according to accepted standards (EN ISO 8655-2:2002 Section 7.2-7.5). However if the laboratory work requires the highest accuracy, the manufacturer’s limits should be used. It is essential that every user should define their own limits, according to the application used and the ambient conditions’ Source: Liquid Handling Application Handbook Tips on how to pipette ThermoLabsystems.
15. What are the common methods of pipette calibration?
The three most common methods for pipette calibration are the gravimetric, photometric/colourimetric and the titrimetric methods.
The gravimetric method is the most common of these three. It involves the highly accurate measurement of a certain mass of water and its conversion to a volumetric unit by taking into account temperature, air buoyancy, humidity, barometric pressure and the cubic expansion coefficient. The combination of these variables results in the determination of a Z-Factor which is used to convert the mass of the water to a volumetric unit. This technique should only be performed by skilled personnel as it is prone to error. The calibration laboratory environment should be well controlled and defined and these variables measured constantly. This method is covered in EN ISO 8655-6:2002 Piston-Operated Volumetric Apparatus: Gravimetric Methods For The Determination Of Measurement Error.
The photometric/colourimetric method involves the use of a reagent kit containing blanks and different dilutions of sample solutions and a photometric instrument. This method is covered by EN ISO 8655-7:2005 Piston-Operated Volumetric Apparatus: Non-Gravimetric Methods For  The Assessment Of Equipment.
The titrimetric method that measures a known amount of NaOH in relation to a pipettes delivery. The delivered volume of pipettes is determined without measuring temperature, humidity, barometric pressure, or evaporation rate. This method is also covered in EN ISO 8655-7:2005.

16. How should pipettes be stored?
Pipettes should be stored upright in a pipette rack. Pipette holders prevent contamination, corrosion and accidental breakage of the pipette.

17. Do you provide storage racks?
Yes we can provide storage racks.

18. What is meant by the Nominal Volume of a Pipette?
Defined by ISO 8655-1: 2002 Section 3.1.5 the nominal volume of a pipette is
 ‘Volume specified by the manufacturer and used for identification and for indication of the measuring range’.
e.g. A fixed volume pipette with volume of 20µl has a nominal volume of 20µl, a variable volume pipette with a volume range of 100-1000µl has a nominal volume of 1000µl.

19. Can my pipette be autoclaved?
In relation to the use of an autoclave it is very important to consult the pipette user manual before carrying out this procedure, for example all FinnPipette Digital models can be autoclaved in one piece at 121°C for 20mins whereas only the tip holder, tip ejector and connecting nut but not any parts of the piston or upper body of a Gilson Pipetman can be autoclaved under the same conditions. It is necessary to calibrate the pipette after autoclaving.

20. How do I prevent cross-contamination while pipetting?
Cross contamination is a major worry for scientists, for example, in PCR work when dealing with small quantities of DNA the most important consideration is avoiding contamination, where even the smallest aerosol contaminate can provide erroneous results.
The main ways to fight this problem are;

• Use Filter Tips. These tips have porous filters whereby air can flow through the filter but the aerosol is retained in the filter thus preventing any of the aerosol entering the tip holder.
• Use of a positive displacement pipette with disposable filter can also be used. There is no direct contact between the pipette and the sample and since the plunger and tip are disposed of after pipetting there is no risk of carryover.

21. What is EN ISO 8655 1-6 (2002); 7 (2005)?
It is an international standard that has replaced the German DIN 12650. It has been adopted in many countries that operate under the ISO system. The standard is divided into 7 parts.   Part 1 defines the general requirements for piston-operated volumetric apparatus, metrological requirements for, maximum permissible errors, markings and information, information to be provided to users for Piston Pipettes (Part 2), Piston Burettes (Part 3), Dilutors (Part 4), Dispensers (Part 5). Part 6 specifies the gravimetric determination of errors of measurement for conformity testing of piston-operated volumetric apparatus whereas Part 7 specifies the photometric and titrimetric determination of errors of measurement of piston-operated volumetric apparatus.

22. Do you provide training?
Yes click here for details.

23. Can we deliver our pipettes to you for calibration?
Yes you can deliver your pipettes to our laboratory any time from 08.00hrs to 18.00hrs Monday to Friday and by special arrangement at the weekend.