A test tube, culture tube or sample tube, is a transparent cylindrical shape generally open at one end and closed at the other, in the form of a finger. Are used, from the beginning of the 19th century, to contain and test various reactions on a small scale.
They have a wide range of practical uses in chemistry, bioscience, medicine, and more.
The spherical bottom prevents loss of mass, due to the absence of corners, when pouring the contents of the test tube and makes cleaning easier
There are several types of test tube materials: glass, plastic, metal, and ceramic. Glass and plastic are the most common, some are designed to be reused, while others are disposable.
There are many types and subtypes of test tubes, when purchasing you should consider the price, heating temperature, ease of cleaning, flexibility of use, size and whether you need of a disposable solution.
◈ Example of glass test tubes
Soda-lime glass, standard glass, is the most common form of glass. It is made up of about 70 percent silica (silicon dioxide), 15 percent soda (sodium oxide), and 9 percent lime (calcium oxide), with much smaller amounts of various other compounds.
Soda lime glass is inexpensive, chemically stable, reasonably hard
Borosilicate glass is produced using 70% to 80% silica (SiO 2) and 7% to 13% boric oxide (B2O3) with small amounts of alkaline sodium oxide (soda) (Na 2O) and d aluminum oxide (AI2O3).
Borosilicate glass has several advantages over soda lime glass. It is less prone to chemical attack, and the coefficient of expansion is lower, so it is more resistant to thermal shock.
Quartz glass combines high thermal shock resistance with high transmission of infrared (IR) radiation. Chemically pure and chemically resistant, it also has excellent high temperature properties
Pyrex Glass is another proprietary type of borosilicate glass with exceptional strength and stability, brilliant transparency, and superior resistance to chemicals, contaminants and drastic temperature changes.
- The types of glass are categorized by several organizations such as ASTM (American Society for Testing and Materials), EP (European Pharmacopoeia) and USP (United States Pharmacopoeia)