Glass Pasteur pipette Glass pasteur pipettes The two types of glass that are usually found in the laboratory and in the Pasteur pipette are Borosilicate glass and Soda lime glass. Borosilicate glass is a widely used glass for laboratory apparatus, as it can withstand chemicals and temperatures used in most laboratories. Borosilicate glass is also more economical since the glass can be fabricated easily compared to other types. Soda lime glass, although not as chemically resistant as Borosilicate glass, are suitable as a material for inexpensive apparatus such as the Pasteur pipette. Plastic Pasteur pipette Plastic pasteur pipettes Plastic Pasteur pipettes, also referred to as transfer pipettes, have their stems and bulbs in the form of a single piece made of soft plastic such as polyethylene. The bulb portion is thinner and therefore "squeezable", while the pipette portion is thick enough to be rigid. They commonly come in 1, 2, 3, and 5 ml which comes with a specific drop size of 10, 20, 25, 35, and 50 µl. The volumes are usually marked on the stem, though the markings are rather crude and are not particularly accurate. A plastic<unk>  is relatively inexpensive and disposable, so they are often used to avoid cross-contamination. In a solution containing cells and/or protein, it reduces the loss of cell and/or protein that binds to glass. Some plastic pipettes include a long flexible tube that can be bent for drawing solution from small volume tubes. Plastic Pasteur pipettes are often used in biology where most media are aqueous and solvent resistance is not important. (Most organic solvents, such as hexane and acetone cannot be used in plastic Pasteur pipettes as the solvent can dissolve the plastic.) The pipettes are also hard to wash and are usually discarded with other biohazard waste after one use. Plastic bulb pipettes are generally not precise enough to be used for exact measurements, whereas their glass counterparts can be extremely precise.
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Contact lens