Einführung in serologischen Pipetten und Pipettierhilfen
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Q1: What is a serological pipette used for in the laboratory?
A serological pipette is a laboratory instrument designed for transferring milliliter volumes of liquid, ranging from less than 1 ml to up to 50 ml. These pipettes feature gradations along their sides for measuring precise volumes and are commonly used with a pipette dispenser to facilitate accurate liquid transfer through partial vacuum creation.
Q2: What are the differences between glass and plastic serological pipettes?
Glass serological pipettes are sterilizable and reusable, making them cost-effective for repeated use in laboratories. Plastic serological pipettes are sterile and disposable, offering convenience and eliminating cross-contamination risks. Both types require a pipette dispenser for liquid transfer and can be selected based on experimental needs and budget considerations.
Q3: How does a pipet-aid work to transfer liquids?
A pipet-aid is a motorized pipette dispenser with two triggers on its handle: the top trigger aspirates liquids by creating partial vacuum, while the bottom trigger dispenses. The nose cone attaches the pipette and houses a filter protecting internal components. Most pipet-aids are battery-powered and offer adjustable settings for controlling dispensing speed, from gravity to forced air blow-out modes.
Q4: How do you read the volume on a serological pipette accurately?
Volume on a serological pipette is read at the gradation mark along the bottom of the meniscus, not at the top of the liquid. The gradation marks line the sides of the pipette, allowing precise measurement of aspirated or dispensed volumes. Careful attention to the meniscus level ensures accurate milliliter volume transfers for reliable experimental results.
Q5: What are common laboratory applications for serological pipettes?
Serological pipettes are useful for mixing cell suspensions and chemical solutions, transferring entire colonies of cells for expansion or analysis, and carefully layering reagents of different densities to create density gradients. These applications support cell culture, mixing, and purification procedures essential in biological and chemical research.
Q6: Why is mouth pipetting dangerous and what is the safe alternative?
Mouth pipetting is an ancient, unsafe technique that can allow liquid to enter the oral cavity, causing serious adverse health effects. A pipette dispenser negates the need for mouth pipetting by using mechanical or motorized means to create partial vacuum for aspiration and dispensing, protecting the researcher from contamination and injury.
Q7: What precautions should you take when operating a serological pipette?
Handle the pipette only above the gradation marks to maintain sterility. Use gentle pressure when aspirating, especially with smaller volumes, to avoid contaminating the filter or damaging the pipet-aid. Avoid touching the pipette tip to non-sterile surfaces, and use firmer pressure only when dispensing larger volumes for faster transfer.
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