Thermo Scientific Pipetting Guide Tips for Good Laboratory Pipetting Part of Thermo Fisher Scientific Thermo Scientific Thermo Scientific Contents Introduction 3 Pipetting Pipetting Guide Pipetting terms 3 Types of pipettes 4 General pipetting guidelines 6 Pipetting techniques 6 Tip information 7 Recommendations for pipetting different compounds 8 Ensuring optimum performance 8 Usage of Finpipette Novus 9 Factors affecting the accuracy of air displacement pipettes 10 Preventing cross-contamination 11 Maintenance of your Finnpipettes 1 Autoclaving 1 UV resistance 1 Calibrating your pipettes (incl. conversion table) 13 On-line pipette calibration 15 General guidelines for decontaminating pipettes 16 Chemical compatibility of plastics 18 Customer support 19 Trouble shooting 19 Thermo Scientific Over 35 Years of Innovation A leader in pipetting For over 35 years we have led the way in liquid handling products and microplate instrumentation. We have always ensured that innovation, ergonomics, accuracy, precision and safety are key aspects of our products’ designs. In 1971 we introduced Thermo Scientific Finnpipettes, the world’s first continuously variable micropi- pettes. In 1976 we introduced the world’s first multichannel pipette. Since then we have continuously improved our pipettes, always leading the way with ergonomic design. Over the last 35 years, innovations such as the improved finger rest, soft-touch tip ejection and super blow-out have made Finnpipettes increasingly user-friendly. Our intensive research program and commitment to our customers forms the foundation for future innovations. The new demands in pipette applications are the key drivers of our product development. To date, over 3 mil- lion Finnpipettes have been sold in 150 countries. Thanks to our extensive R&D and feedback from the field, Thermo Scientific Pipetting Guide Finnpipettes are the preferred choice for optimal liquid handling results, with our multichannel pipettes being the market leader worldwide. Most clinical and research laboratories are equipped with manual or electronic pipettes for dispensing liquids. The amount of liquid can range from ml’s to below 1 μl, especially when using expensive reagents. In all cases, the dispensing must be accurate and precise to guarantee good research results. Not only the pipette but also the tip plays a crucial role as these two form together the pipetting system. As pipetting is often a repetitive task, the pipettes must be designed so that the risk of hand and upper limb stress is minimized. We offer a wide range of high-quality manual and electronic pipettes and pipette tips to ensure good laboratory pipetting. In this guide we will outline some practical aspects of pipetting to help you to get the best possible results. Pipetting terms The following terms are used throughout this guide and in instructions for use. We will explain them briefly: Aspirate – to draw up the liquid into the pipette tip Dispense – to discharge the liquid from the tip Blow-out – to discharge the residual liquid from the tip Calibration check – to check the difference between the dispensed liquid and the selected volume Adjustment – altering the pipette so that the dispensed volume is within the specifications 3 Types of pipettes Types Thermo Scientific Types of pipettes There are two types of pipettes: air displacement and positive displacement pipettes. Pipetting Pipetting Guide Both types of pipettes have a piston that moves in a cylinder or in a capillary. In air displacement pipettes, a cer- tain volume of air remains between the piston and the liquid. In positive displacement pipetting, the piston is in direct contact with the liquid. Air displacement pipettes are meant for general use with aqueous solutions. Positive displacement pipettes are used for high viscosity and volatile liquids. Air displacement pipetting How does an air displacement 3. After immersing the tip into pipette work? the liquid, the operating button is Air displacement pipetting, used released. for standard pipetting applications, 1. The piston moves to the appropri- is highly accurate. However, condi- ate position when the volume is set. This creates a partial vacuum and tions such as atmospheric pressure the specified volume of liquid is aspirated into the tip. as well as the specific gravity and 2. When the operating button is viscosity of the solution may have pressed to the first stop, the piston an effect on the performance of air expels the 4. When the operating button is displacement pipettes. same volume of air as indicated on pressed to the first stop again, the the volume setting. air dispenses the liquid. To empty the tip completely the operating button is pressed to the second stop (blow out). piston pipette tip 4 Types of pipettes Types Positive displacement pipetting How does Thermo Scientific Pipetting Guide Finnpipette Stepper work? The repeater pipette Thermo 50 ml 50 Scientific Finnpipette® Stepper uses 1. The piston inside the tip moves ® the positive displacement principle. up when filling the tip with liquid. Finntip Stepper microsyringe tips have a piston inside a cylinder unit; these 2. When the dispensing lever is tips are disposable. This helps to pressed down, the piston moves 1=1 ml 1=1 avoid sample to-sample cross-con- down and the selected volume is tamination (also known as sample dispensed. The dispensing lever has Thermo Scientific carry-over), and contamination due to be pressed once for each dis- to the aerosol effect. pensing stroke (= step). Finnpipette Focus Finnpipette Stepper 5 Gnereal pipetting guidelines Gnereal Thermo Scientific General pipetting guidelines Check your pipette at the beginning • Pre-rinsing (three - five times) the • Avoid contamination to or from Pipetting Pipetting Guide of your working day for dust and tip with the liquid to be pipetted fingers by using the tip ejector. dirt on the outside. If needed, wipe improves accuracy. This is especially with 70% ethanol. important when pipetting volatile • Always store pipettes in an compounds since it prevents liquid upright position when not in use. • Check that you are using tips rec- dropping out of the tip. Finnpipette stands are ideal for this ommended by the manufacturer. To purpose. ensure accuracy, use only high-qual- • Pipette parallel samples in a simi- ity tips made from contamination- lar way. free polypropylene. • Avoid turning the pipette on its • Tips are designed for single use. side when there is liquid in the tip. They should not be cleaned for Liquid might go to the interior of reuse as their metrological charac- the pipette and contaminate the teristics will no longer be reliable. pipette. Forward pipetting Ready position 1 2 3 4 Otherwise no: formation of bubbles 3. Dispense the liquid into the or foam in the tip or in the test tube receiving vessel by gently press- First stop or well. ing the operating button to the first Second stop stop. After one second, press the 1. Press the operating button to the operating button to the second first stop. stop. This action will empty the tip. Yes: when pipetting and mixing Remove the tip from the vessel, a sample or reagent into another 2. Dip the tip into the solution to a sliding it along the wall of the liquid. depth of 1 cm, and slowly release vessel. the operating button. Withdraw The forward technique is recom- the tip from the liquid, touching it 4. Release the operating button to mended for aqueous solutions like against the edge of the reservoir to the ready position. buffers, diluted acids or alkalis. remove excess liquid. Repetitive pipetting Ready position 1 2 3 4 1. Press the operating button to the 3. Dispense the liquid into the second stop. receiving vessel by gently press- First stop ing the operating button to the first Second stop 2. Dip the tip into the solution to a stop. Hold the button in this posi- depth of 1 cm, and slowly release tion. Some liquid will remain in the the operating button. Withdraw Yes: especially for adding of rea- tip, and this should not be dis- the tip from the liquid, touching it gents into tubes or into the wells of pensed. against the edge of the reservoir to a microtiter plate. remove excess liquid. 4. Continue pipetting by repeating This technique is intended for steps and 3. repeated pipetting of the same volume. 6 Reverse pipetting viscosity or a tendency to foam. 3. Dispense the liquid into the Ready position 1 2 3 4 5 This method is also recommended receiving vessel by depressing the First stop for dispensing small volumes. It is operating button gently and steadily Pipetting Guide only possible with air displacement Second stop to the first stop. Hold the button pipetting General guidelines pipettes. in this position. Some liquid will Yes: for pipetting of samples or 1. Press the operating button to the remain in the tip, and this should reagents when no mixing into second stop. not be dispensed. another liquid is required. 2. Dip the tip into the solution to a 4. The liquid remaining in the tip depth of 1 cm, and slowly release can be pipetted back into the origi- Reverse pipetting avoids the risk of the operating button. This action will nal solution or thrown away with splashing, foam or bubble formation. fill the tip. Withdraw the tip from the tip. Thermo Scientific Thermo Scientific the liquid, touching it against the The reverse technique is used for 5. Release the operating button to edge of the reservoir to remove pipetting solutions with a high the ready position. excess liquid. Pipetting of heterogeneous samples 1. 3. + 4. Press the operating button to Ready position 1 2 3 4 5 6 Press the operating button to the first stop. Dip the tip into the sam- the first stop and release slowly to First stop ple.