Test tube

November 1, 2021

Elongated and graduated glass tube, closed at one end, used as a container for liquids or gases, which is intended to measure their volume.

What is it?

It is one of the most widely used volumetric instruments in laboratories. It is a cylinder made of glass with a scale that allows it to contain liquids and measure their volume accurately. It has a sealed bottom, an opening at the top and a base on which it can be attached.

We can find different sizes, from 10 ml, 25 ml, 50 ml and 100 milliliters to take different measurements.

They are used in chemical analysis, since the substance to be analyzed is measured with the help of the test tube. It is not a precision instrument, if a high level of precision is required, it is necessary to use a pipette.

What is it for?

This measuring instrument allows us to know the volume more quickly than a pipette, it even allows us to measure higher volumes, although it has a much lower precision.

Test tubes are also used to contain liquids.

How to use

To use a pipette correctly, you only need to follow the following steps:

  1. Clean the cylinder carefully before using it.
  2. Rinse with the liquid to be measured.
  3. Add the liquid until you reach the capacity you want.
  4. If the liquid has exceeded the required amount, return the liquid completely and pour it back in. If not, remove the excess with a pipette until the required amount is reached.
  5. Later, add it to the container where you will perform the analysis.


The specimens have certain characteristics:

  • Some are made of plastic, which makes them less brittle and more resistant to hydrofluoric acid, which can degrade glass.
  • They have a base of support.
  • At the top they end in a spout that allows the measured liquid to be poured.
  • They are made of a transparent glass or borosilicate tube.
  • They are a few centimeters in diameter and have a graduation that goes from 5 ml to the maximum level offered by the cylinder, generally 25 ml, 50 ml, 100 ml and the largest can contain up to 2 L.


There are two types or classes of specimens

Class A specimen: These are those made following strict quality controls and are used in testing laboratories and to validate analytical methods.

Class B specimen: They are used in school and university laboratories where extreme levels of precision are not required. They are usually made of plastic and their price is very low.

Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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