Difference Between Cuvette and Test Tube

The key difference between cuvette and test tube is that the cuvette has two straight sides whereas the test tube has no straight sides. Further, cuvettes and test tubes have different applications and chemical compositions as well.

Both cuvette and test tube have common use in analytical chemistry as equipments for analysis. Both these are tube-like equipments that are open at one end and sealed at the other end.

What is a Cuvette?
A cuvette is a tube-like equipment with two straight sides and two circular or straight sides. Further, it has one end sealed while the other end is open. The material used to make it is highly transparent and clear. Ex: plastic, glass, fused quartz, etc.

The use of cuvette in spectroscopic analysis is to keep the sample inside a spectrophotometer. Inside the spectrophotometer, a light beam passes through the sample to measure the absorbance of light by the sample. There, the light beam should pass through the cuvette.

The cross-section of a cuvette looks like a rectangle. Therefore, a cuvette is like a rectangular test tube. When using a cuvette in an analysis, first the cuvette is filled with the sample to about 80% of the volume inside the cuvette. However, this volume will be different from one cuvette to another.

There are several different names used to name a cuvette. Ex: cell, capillary, quartz cell, spectrophotometer cuvette, etc. In a cuvette, there are two sides through which the light beam passes. These are straight sides. The scratches on these sides can cause light scattering, thus, creating errors in the final result. Therefore, handling the cuvettes carefully to avoid any scratches is important. Even fingerprints and water droplets can cause errors. Therefore, this surface has to be cleaned with a clean cloth or gauze.

What is a Test Tube?
A test tube, also known as a culture tube or sample tube, is a tubular equipment made of glass or plastic. Further, the tube has an opening at one end and sealed at the other end. The sealed end is most of the times circular, flat or conical. Therefore, we should use a special type of racks known as test tube racks to keep the test tubes upright.

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