Lab tubes are cylindrical containers used to hold substances in scientific applications. They come in a variety of lengths and capacities, from 0.1mL plastic tubes for use with DNA tests to 600mL tubes for use with laboratory evaporators. Tubes can be made of flint glass for durability, borosilicate glass for heat resistance and reuse, or plastic such as polypropylene or polystyrene for one-time use. Some lab tubes have graduations to indicate approximate measurements, marking spots for labeling, or caps or stoppers to contain substances.
A test tube is designed to mix or heat chemicals, hold samples, or facilitate biological cell cultures. Typically, test tubes are made of glass or plastic and have a u-shaped, v-shaped, or flat base. Glass test tubes sometimes have beaded rims for ease of pouring and commonly hold substances for use in chemical reactions or sampling applications. They can be made of borosilicate glass to resist high temperatures associated with heating and boiling, and they range in capacity from 3mL to 75mL. Cell culture tubes may be used in medical facilities to collect blood, in laboratories for growing mold or bacteria, and in dairy testing applications. Many tubes are made to fit standard laboratory apparatus including centrifuges, or racks for storage, agitation, or refrigeration.
Plastic test tubes with caps, called PCR tubes, hold a DNA reaction mixture during the polymerase chain reaction (PCR) technique in biological and medical research applications. Commonly made of polypropylene, polyethylene, or polycarbonate, PCR tubes come in a strip and may have attached caps. Each tube has a v-shaped base and can hold between 0.1mL and 1.2mL. Micro centrifuge tubes are used in laboratory applications with a micro centrifuge, and are made of polypropylene, polyethylene, or polystyrene. Capacities range from 0.2mL to 50mL, and they come with a snap cap to seal the contents. Sometimes they are color coded for identification. Capillary tubes and NMR tubes have narrow bores for sampling in medical and biological research. NMR tubes are designed to hold samples in nuclear magnetic resonance spectroscopy. They are made of borosilicate glass for durability and heat resistance.