What is cuvette (Plastic vs. quartz cuvettes)

The tiny container that is used to measure solutions for spectrophotometers or other lab applications is called a cuvette. Typically, these tiny containers come in similar sizes with different volumes.

You can have these tiny tubes with two or four polished sides. However, ones with two polished sides have two frosted sides that aren’t used to emit lights. Again, the light emits in a 90-degree pathway through a four-side polished one.

You need the best cuvettes to get your job done in the laboratory. However, people often get confused thinking about whether to choose plastic or quartz.

What is cuvettes

What is a cuvette used for?

Chemists use cuvettes in their labs to measure the absorbance of a particular solution at a specific wavelength. However, absorbance means measuring the percentage of light transmission through the polished side of it.

Mainly, it holds the solution depending on the capacity or volume. Spectrophotometer and fluorometer are two common machines used to take these tubes with the analysis solution.

Now, the curious mind may be asking for what else job they come useful.

  1. Absorbance or percentage of light transmission.
  2. Measuring transmittance.
  3. Fluorescence intensity analysis.
  4. Measuring the fluorescence polarization.
  5. Timing of the solution.

All these are done with either a spectrophotometer or fluorometer. However, you can use these as simple solution holding tubes as well. In that case, either plastic or quartz cuvettes will do the same job.

On the other hand, to analyze something through the spectrophotometer, using quartz or glass ones is recommended. The reason is that plastic ones can’t work beyond the visible wavelength.

Comparison between plastic and quartz cuvettes

Plastic vs. quartz cuvettes

When the question is about disposable and reusable cuvettes, experts suggest plastic and quartz. Each of these tiny tubes is appropriate for a specific situation. Therefore, both of these have pros and cons.

Check out the following comparison chart that shows how plastic and quartz ones are different.

Comparison

Plastic cuvette

Quartz cuvette

Usability

Disposable

Reusable

Wavelength range

380 nm to 780 nm

190 nm to 3,500 nm

Construction material

Polystyrene

Chemical-resistant material

UV light transmission

No

Yes

Temperature resistance

Low

High

Durability

Not prone to breaking

Fragile

Cost

Cheap

Comparatively expensive

It seems that quartz ones offer extra facilities to the user compared to plastic ones. Being a chemical-resistant material, it's less prone to damage. But the construction is fragile than plastic.

Our experts recommend taking every care of the quartz ones and carefully reusing them. Another disadvantage why people would recommend plastic is the pricing. As quartz offers more reliability, the price stays higher too.

At last, if you are not one that loves to clean these tubes immediately after using it, going for plastic ones will be a great decision.

How many types of cuvettes are there?

Before going deep into different cuvettes types, one thing you need to decide is whether you need disposable or not. Disposable ones have plastic construction, which is not reusable.

On the other hand, reusable ones have quartz, glass, and sapphire construction. Therefore, you can have four different types to do your laboratory jobs with perfection.

  1. Plastic cuvettes are disposable.
  2. Quartz offers an extended transmission range.
  3. Glass is suitable for UV applications.
  4. Sapphire ones are the most durable and expensive ones.

Check out the below chart that shows the wavelength range for each of these tiny tubes.

Types

Wavelength range

Plastic

380 nm to 780 nm

Glass

340 nm to 2,500 nm

UV quartz

190 nm to 2,500 nm

IR quartz

220 nm to 3,500 nm

Sapphire

250 nm to 5,000 nm

Without making you further wait, let’s quickly get into these different types and let you decide which one is adequate for your laboratory applications.

Plastic

If you are worried about the breaking of tiny tubes like cuvettes, plastic is a good option for you. However, you also need to know that it's disposable, and you can't use it a second time that can result in contamination.

Plastic ones can only work within the visible spectrum range from 380 nm to 780 nm. The most commonly used materials to construct these are polystyrene and polymethyl methacrylate.

Glass

Coming from the visible range, glass cuvettes can work within the IR range as well. The spectrum range for these is from 340 nm to 2,500 nm. It's the most commonly used type in laboratories for checking absorbance.

Whether you have ultra-violet applications or applications within a visible wavelength, glass ones come in handy on both occasions.

Quartz

For extended reliability, while using the solution in spectrophotometer and fluorometer, quartz is the ideal option. Although it is a little upgraded version of glass cuvettes, the performance level is way up.

However, UV quartz and IR quartz are two different types here. The optimal wavelength range for UV quartz is from 190 nm to 2,500 nm. Again, IR quartz offers a wavelength range from 220 nm to 3,500 nm.

Sapphire

Amongst these cuvettes, sapphire is the strongest, durable and expensive one. It can transmit light within a wavelength from 250 nm to 5,000 nm. Being hard, it's not prone to get easily damaged.

What’s the volume of cuvettes?

A standard cuvette is 45 mm tall with an outer dimension of 12.5 mm by 12.5 mm. But what makes them different is the inner capacity of holding liquid.

It is called the volume, which differs according to the need. The standard volume is 3.5 ml.

  1. 3.5 ml is the standard volume.
  2. Semi micro ones have 1.4 to 1.7 ml volumes.
  3. Micro ones come with 0.35 to 0.7 ml volume.
  4. Some cuvettes come with 2.5 to 4.5 ml volume as well.

Are cuvettes reusable?

Yes, cuvettes are reusable except for plastic. Plastic is disposable, which can cause contamination in the analysis if reused. Therefore, no expert chemist suggests using plastic ones more than once.

However, using quartz one for reusability is the ideal decision. After every time you use it for analysis of any chemical sample, you need to clean and dry it. Thus, it becomes usable for the next time.

How to clean a cuvette?

By cleaning a cuvette, you can make it ready for the next experiment immediately. However, you need distilled water, ethanol, acetone, lint-free wiping paper, and a dry blower. Follow the steps below to clean it properly.

  1. Put a few drops of distilled water in it.
  2. Rinse it and drop water in the wastage bucket.
  3. Repeat the process 3/ 4 times.
  4. Now, use a few drops of ethanol inside it.
  5. Rinse it to get rid of the water spots.
  6. Put some acetone inside then.
  7. It will quicken the drying process.
  8. Hold the cuvette carefully.
  9. Take a lint-free wipe paper and tap carefully on it.
  10. Use a dry blower to get it dry immediately.

Useful links

https://www.youtube.com/watch?v=bkp7wUi-48s

https://www.youtube.com/watch?v=tgLQMQS1o88

https://cuvet.co/understanding-cuvette-volume-material-path-length-etc/

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