Search Thermo Fisher Scientific
- Order Status
- Quick Order
-
Don't have an account ? Create Account
Recommendations for Pipetting Liquids
Quick links
- Forward, Reverse, Repetitive, & Heterogeneous Sample Pipetting
- 10 Steps to Improve Pipetting Accuracy
- Pipette Accuracy vs. Precision
- Factors Affecting Pipette Accuracy
- Preventing Cross Contamination
Complete the form and download a pdf version of the GLP Guide.
Getting started
- Check your pipette at the beginning of your working day for dust and dirt on the outside. If needed, wipe with 70 percent ethanol.
- Check that you are using tips in agreement with the manufacturer's specification. Thermo Scientific pipettes are calibrated using Thermo Scientific pipette tips.
- To ensure accuracy, use only high-quality tips made from contamination-free virgin polypropylene.
- Tips are designed for single use. They should not be cleaned for reuse, as their metrological characteristics will no longer be reliable.
- Pipette parallel samples in a similar way, e.g., pipette in the same position with the tip in the same depth, using the same speed for plunger movements.
- Avoid turning the pipette on its side when there is liquid in the tip. Liquid might get into the interior of the pipette and contaminate the pipette.
- Avoid contamination to or from hands by using a tip ejector for tip removal.
- Always store pipettes in an upright position on a stand when not in use.
| Solution and / or compound | Examples | Pipette | Pipette Tip | Pipetting technique | Comments |
|---|---|---|---|---|---|
| Aqueous solution | Buffers, diluted salt solutions | Air displacement | Standard | Forward | |
| Viscous solution | Protein and nucleic acid solutions, glycerol, Tween 20/40/60/80 | Air displacement Positive displacement | Standard or wide orifice, Low Retention Positive displacement | Reverse | Pipette slowly to avoid bubble formation. |
| Volatile compounds | Methanol, hexane | Air displacement Positive displacement | Filter/Barrier Positive displacement | Reverse | Pipette rapidly to reduce the effect of evaporation. Carbon filter tips protect the integrity of the pipette by eliminating exposure to harmful vapors. |
| Body fluids | Whole blood, serum | Air displacement | Standard or wide orifice tip | Heterogeneous* | Residual liquid can be found on the outer surface of the tip. Wipe the tip against the edge of the vessel to remove this liquid before dispensing. |
| Nucleotide solutions | Genomic DNA, PCR products | Air displacement Positive displacement | Filter/Barrier or wide orifice Positive displacement | For genomic DNA wide orifice tips can be used to eliminate mechanical shearing. | |
| Radioactive compounds | 14Carbonate, 3H-thymidine | Air displacement Positive displacement | Filter/Barrier Positive displacement | Forward | |
| Acids/alkalis | H2SO4, HCI, NaOH | Air displacement | Filter/Barrier | Forward | |
| Toxic samples | Air displacement Positive displacement | Filter/Barrier Positive displacement | Forward or reverse |
*With blood or serum reverse technique is another option. During the aspiration and dispensing, use very slow plunger movements. When aspirating, hold the tips in the liquid for a few seconds, after the plunger is in the upper position. Also, when dispensing, move plunger slowly and wait a few seconds when plunger is in the down position.
