The History of the Name and their Role in Modern Spectrophotometry
The word “cuvette” is derived from the French word “cuve”, or large vessel.
Essentially, the word is the diminutive form of “cuve”, meaning “little vessel”.
The use of this word dates back to 1909, and it has been used to describe multiple types of vessels.
However, in a UV-Vis laboratory, it can only mean one thing. They are about 3mL in volume with clear walls used for UV-Vis and Fluorometry samples.
We’ve talked about Spectrophotometry before in our previous article “How and When to use a Spectrophotometer”, and when we did, we discussed Beer-Lambert’s Law.
However, one thing we didn’t emphasize is how important it is to be able to SEE the sample through the container.
That’s why it’s good to be finicky about what your cuvettes are made of.
In this article we’ll discuss:
- What cuvettes are used for
- Materials and types
- Cleaning and maintenance
- Where to buy them
Breaking Down Cuvettes: Materials, Uses, and Best Practices
What is a Cuvette?
They are small, clear containers designed to fit inside the imaging chamber of a UV-Vis Spectrophotometer or Fluorometer.
Most are rectangular, four-walled, and have a central diameter of 10mm. This central diameter is equal to the length of the light path in the Beer-Lambert equation.
The central rectangular portion typically measures 12.5x12.5 mm and there are at least two walls designated for imaging.
The type of material used varies, but the quality of the results depends a lot on whether materials are selected carefully.
Materials and Types
Glass and quartz are the traditional materials used for making these devices because of their clarity, but Polystyrene and Polymethylmethacrylate (PMMA) are replacing them.
These plastics are ultra-clear, washable and good for multiple uses, but also able to be disposed of and recycled easily.
Plastics like these are cheaper and easier to manufacture than glass or quartz, and the added bonus is that they are more resistant to breaks when dropped.
The key to choosing what type of material to use is based on what you are testing–small molecules like nucleic acids sometimes stick to containers.
The other important factor is the range of light you’ll be imaging in. Different materials have different ideal ranges.
Cuvettes in Action: How they Work in Common Applications
Their Role in Spectrophotometry
What makes them unique and functional as tools for UV imaging is their ultra-clarity.
Certain plastics absorb too much light, which renders them useless for UV imaging readings.
Polystyrene and PMMA don’t absorb much in the way of visible light, so they provide accurate readings with variance below ±1% absorbance.
Choosing the Right Container
When it comes to selecting the right type, the main selection factors are volume and UV range of interest.
If you are analyzing nucleic acids, you will not be using plastics and should opt for quartz over glass to prevent adsorption to the container walls.
However, modern spectrophotometers often use nanodrop methods and don’t require them at all.
For other samples, you will choose between macro and micro chamber sizes. The volume of a sample in your workflow dictates which to use.
Compare the semi-micro volume option to the standard volume options
PMMA is suitable for the 280-800 nm transmittance range, whereas Polystyrene works within the 340-800 nm range.
Both plastics are equally reliable within their working range, but polystyrene is somewhat more thermal and chemical resistant.
In Summary:
- Glass is no good for nucleic acid!
- Quartz is expensive and difficult to keep clean, but versatile
- Polystyrene and PMMA are suitable for most imaging applications (from 340-800 nm)
- Plastics cannot be used accurately for wavelengths lower than the ranges indicated, which makes them less appealing than quartz in some cases
- Macro and micro vessels are available for different sample volumes
Cleaning and Maintenance
Because they are designed with convenience in mind, they’re fairly easy to clean.
You will need a skinny bottle brush, glassware detergent, and 70% ethanol to clean them following each use.
- First, dump the sample solution in the appropriate waste container.
- Next, rinse with water.
- Add detergent to a bottle brush and scrub the inside gently.
- Rinse again with water, and then rinse and dry with 70% ethanol.
Plastics are only intended to be used a few times before disposal.
Eventually the container walls will begin to develop cloudiness and discoloration, and this will interfere with results.
Shop for Spectrophotometry Supplies Online with Stellar
At Stellar Scientific, we proudly carry our own line of Polystyrene and Polymethylmethacrylate cuvettes for Spectrophotometry and Fluorometry.
Our supplies are guaranteed to offer readings within ± 1% absorbance. They are made from crystal clear plastics and available in several sizes and in bulk packages.
If you need any help with your order, you can always contact us by e-mail or by phone using our information on the contact us page.
Footnotes:
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- “Understanding Cuvette Volume, Material, Path Length Etc. | Cuvet.Co Cells.” Cuvet Co, 3AD, cuvet.co/understanding-cuvette-volume-material-path-length-etc/. “Accessed 17 July 2024.
- US6249345B1 - Cuvette.” Google Patents, Google, patents.google.com/patent/US6249345B1/en. Accessed 17 July 2024.
- “Cuvette.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/cuvett... Accessed 17 Jul. 2024.