Pipettes are fundamental laboratory tools used for precisely measuring and transferring liquid volumes in scientific and medical settings. Maintaining these instruments in a clean state is paramount for reliable scientific work. Proper cleaning protocols ensure the integrity of experiments and the longevity of the pipettes themselves.
Why Pipette Cleaning is Essential
Maintaining clean pipettes is fundamental for achieving dependable experimental outcomes. Even minute residues or contaminants within a pipette can significantly compromise the accuracy of liquid measurements, leading to unreliable data and incorrect scientific conclusions. Beyond accuracy, cleaning prevents cross-contamination between samples. Contaminants like biological materials or chemicals can adhere to pipette surfaces. If not removed, these can transfer to subsequent samples, invalidating results. Regular cleaning also extends the functional lifespan of pipettes.
Gathering Your Cleaning Supplies
Effective pipette cleaning requires specific tools and solutions, including distilled or deionized water for rinsing, as tap water can leave mineral deposits. Cleaning agents include mild laboratory detergents, 70% ethanol, or isopropanol. Specialized agents like sodium hypochlorite for nucleic acid removal or specific laboratory cleaning agents for proteins may also be used. Brushes designed for laboratory glassware are helpful for scrubbing away stubborn residues. Beakers or large containers are needed for soaking pipettes, and drying racks or lint-free cloths for the final drying stages.
Step-by-Step Pipette Cleaning Methods
Cleaning protocols vary depending on the pipette type and the level of contamination.
Routine Cleaning
For routine daily cleaning of external surfaces, wiping with a lint-free cloth moistened with 70% ethanol or isopropanol is sufficient. Pay attention to areas like the body, buttons, and tip cone, ensuring compatibility of cleaning agents with the pipette’s materials.
Deep Cleaning for Glass Pipettes
Deep cleaning involves more thorough procedures. For glass volumetric and serological pipettes, immediate soaking after use in a mild detergent solution is recommended to prevent residue from drying. Immerse the pipettes in warm soapy water, then use appropriately sized brushes to scrub the interior and exterior surfaces. After scrubbing, rinse thoroughly with running tap water, followed by multiple rinses with distilled or deionized water to remove all detergent residue.
Deep Cleaning for Mechanical Micropipettes
For internal cleaning of mechanical micropipettes, disassembly of the lower parts is often necessary; always consult the manufacturer’s instruction manual for specific disassembly and cleaning guidance. Once disassembled, individual components like the piston and tip holder can be cleaned. For aqueous or general contaminants, rinsing or wiping parts with distilled water or 70% ethanol is effective. If contamination involves nucleic acids, immersion in a 3% sodium hypochlorite solution, followed by thorough rinsing with distilled water, can reduce contamination. For proteins, detergents are preferred, and alcohol should be avoided as it can cause proteins to set.
Safety and Final Steps
Safety precautions are paramount during any cleaning process. Always wear appropriate personal protective equipment, including laboratory gloves and eye protection, to shield against chemical exposure and potential splashes. When handling glass pipettes, exercise care to prevent breakage, especially during scrubbing or when inserting into pipette bulbs. Ensure all parts are completely dry before reassembly to prevent moisture-related issues or contamination.
Proper Drying and Storage
Drying
After cleaning, thorough drying is crucial to prevent water spots, microbial growth, and subsequent contamination. For glass pipettes, air drying on specialized racks with the open end facing downward allows water to drain and prevents dust. Electric drying racks or glassware washers with built-in drying cycles offer faster, more efficient drying. If oven drying is used for heat-resistant glass, moderate temperatures are advised to avoid affecting calibration.
Storage
Once completely dry, proper storage maintains pipette cleanliness and functionality. Mechanical pipettes should be stored vertically on dedicated stands or racks, preventing internal liquid entry and protecting against damage. Storing them away from excessive heat or moisture helps preserve their integrity. Removing pipette tips before storage is important to prevent cross-contamination and moisture buildup.