UV vis Cuvette: 4 Steps for a Better Decision
A cuvette is a tiny, transparent rectangular container used in spectrophotometric studies that comes in a variety of choices of materials, quality levels, and dimensions (pathlengths and volumes). In the visible range of 320 to 2500 nm, glass cuvettes are cost-effective for measurements. Quartz material cuvettes are transparent over the whole UV and visible spectrum, from 190 to 2500 nm, making them an excellent choice for UV vis spectroscopic investigations.
In this article, we are going to discuss some factors to consider in order to make a better decision when choosing a UV vis cuvette.
Introduction to UV vis Cuvettes
Absorbance studies have become a standard for analyzing a wide range of solutions and particles. Under these conditions, light is directed through the solutions in a certain pattern.
Liquids are used in most laboratory absorption investigations, either as pure solvents or as solutions of light-absorbing substances in clear solvents. This necessitates the use of a cuvette capable of holding these liquids.
The cuvette used to measure absorbance in the UV-Vis spectrophotometer is critical, as solutions are put within the cuvette for examination. Additionally, the choice is difficult because of the variety of UV vis cuvettes available.
Varieties of different UV vis cuvettes
This article gives an introduction to the UV vis cuvette: material, path length, and volume. Then, types of UV vis cuvettes are provided. It also speaks about the way of the usage of cuvettes. Subsequently, it discusses how different factors affect the selection of UV vis cuvette in the spectroscopy system.
This article provides an overview of the UV vis cuvette, including its material, path length, and volume. Following that, many types of UV vis cuvettes are discussed. Additionally, it discusses the methods in which cuvettes are used. Following that, it examines how various factors influence the UV vis cuvette selection for the spectroscopic system.
What is UV vis Cuvette?
- The most popular UV vis cuvettes refer to cuvettes with rectangular shape test tubes, made of quartz material, to be used in the UV vis spectroscopic measuring systems. They, like standard test tubes, are used to store aqueous solutions. Normal test tubes are useful in chemical reactions. UV vis cuvettes, on the other hand, are used in UV-Vis spectrophotometers or fluorometers to determine the transmittance or absorbance of radiation at a certain wavelength within the UV and visible range of 190 – 2500 nm.
- The solution must be put in the UV vis spectrophotometer’s light path. The UV vis cuvette is for this purpose. Typically, 80% of the cuvette’s capacity is filled. However, the filling volume differs amongst cuvettes. A micropipette is used to inject the sample straight into the cuvette, and the cuvette is ready for use.
Some Bestselling UV vis Cuvettes
Other Names for UV vis Cuvette
UV vis Cuvettes are called by various different names. They are as follows:
- UV vis Cells
- Uv vis Cuvette Cell
- Sample UV vis Cuvette
- Quartz UV cell
- Spectrophotometer UV Cuvette
- Absorption UV vis Cell
What is spectrophotometry used for?
Spectrophotometry is a widely used and affordable technique for determining the quantity of light absorbed or the concentration of compounds in a solution. It works by passing a laser beam across the sample, and each component in the solution either absorbs or transmits light at a certain wavelength.
UV-Vis Spectroscopy (or Spectrophotometry) is a quantitative technique for determining how much light is absorbed by a chemical material. This is accomplished by comparing the intensity of light passing through a sample to that passing through a reference sample or blank.
What is the spectrum range of UV vis spectroscopy?
UV-vis spectroscopy is usually referred to as a general technique due to the fact that the majority of molecules absorb in the UV-Vis wavelength range. The ultraviolet spectrum ranges from 100 – 400 nm, whereas the visible spectrum is from 400 – 700 nm. The wavelength range of 100 – 200 nm is called deep UV.
When using a UV-Vis spectrophotometer to measure absorbance, choosing the right cuvette is critical, as each cuvette material has its own set of advantages and disadvantages. The material is chosen based on the specific UV spectroscopy application.
A UV vis cuvette with exact dimensions, such as a 10mm path length, is usually chosen. UV vis cuvette for spectrophotometry is transparent to the wavelength of light in the UV vis ranges for the measurements. As a result, the cuvette itself doesn’t create any issues during the research.
Some 10mm cuvettes with Different Caps or Numbers of Clear Walls
The main problem is that we can’t define the cuvette in this way due to the wide range of materials (usually quartz, glass, and some plastics) used to make them. As a result, it’s easy to become perplexed about which option to choose. Let’s start with a fundamental understanding of their material needs, and then compare and contrast different types of cuvettes.
Step I: Choosing the Suitable Material
Different transparent materials, such as optical glass, quartz, or clear plastic, are widely used to make cuvettes. All of these materials appear to be absolutely clear and suitable for all sorts of absorbance investigations at first glance. However, each material has different light absorption qualities, and it’s vital to be aware of these optical features when choosing a cuvette material.
If you don’t pay attention to these aspects of the UV spectroscopy cuvette, you’ll have problems with the absorbance studies and the findings you get will be inaccurate.
The optical properties of such materials are examined in this article to assist you in making the best decision possible before proceeding with absorbance measurements.
Regardless of the material used, keep in mind that cuvettes, with the exception of transparent plastic cuvettes, are delicate and must be handled with care. The last article, Proper care and handling of UV – Vis absorption measuring cells, discussed the measures that must be taken while handling cells and ensuring that your measurements are accurate.
Now let’s look at the many sorts of cuvettes that are available.
Available Materials for Cuvettes
Cuvettes may be found in a variety of materials, including:
Cuvette of Optical Glass:
Because of their cheaper cost, glass cells are most commonly used in school and college undergraduate laboratories. The optical glass absorbs light in the visible and infrared ranges from roughly 350 nm to 2500 nm, which covers the bulk of biological and inorganic species. Glass, on the other hand, absorbs a lot of UV light and isn’t suitable for wavelengths below 350 nm, which is required by UV vis spectrophotometry.
Optical Glass Cuvettes
Cuvette Made of Plastic:
Transparent plastic cuvettes, similar to glass material, are used to test absorbance in the visible range. Such cuvettes also have the advantage of being unbreakable, however, they cannot be utilized in UV absorbance experiments or with some organic solvent chemicals. Note: UV plastic cuvettes are also available now for wavelengths 285-750 nm.
UV-vis or Vis Plastic Cuvettes
Cuvette of Quartz:
Quartz is more costly than glass and UV transparent plastic, but it has the advantage of covering both UV and visible wavelengths starting at 190 nm. It is, however, even more fragile than glass, and cuvettes must be handled with extreme caution.
Some Examples of Quartz Cuvettes
Now that you’ve examined the specific qualities of these materials, let’s compare them and see which one will work best for you.
More Detailed Comparison of the Materials
Here are some of the variables to consider while deciding between a plastic cuvette, a glass cuvette, and a quartz cuvette.
- Budget is an important consideration when selecting laboratory equipment or solutions. Plastic is the most cost-effective cuvette of the available choices. The optical glass cuvette is next, followed by the quartz cuvette. So, if you’re on a budget, plastic will be a wonderful option to consider.
- Reusable: Plastics are typically used once and then discarded. You can use them once or several times, depending on the manufacturer’s instructions. Then you’ll have to swap them out. Glass and quartz, on the other hand, are both reusable materials. They will stay in good form for a long time if you properly maintain them.
- Transmission: The simple guideline for this element is to see which material has the most ‘light transmission,’ ensuring that the research remains transparent. In this regard, quartz stands out. In both visible and UV light, the material stays transparent. As a result, it’s simple to utilize for UV-light spectrum sample measurements. Glass and plastic materials, on the other hand, are best for visible light investigations but not for purity and concentration assessments.
Apart from these characteristics, quartz possesses the highest thermal resistance of any material. It’s also vital to consider when selecting a cuvette. Our molded type UV vis cuvettes can withstand temperatures of up to 1200°C.
By now, it should be evident that each of the available cuvette variants is superior in some way. Prior to selecting one, the precise purpose and equipment must be specified. While plastic is not ideal for UV-range study, it is an economical solution for all visible-light range experiments.
It is critical to understand that air oxygen absorbs significantly less than 200 nm, whereas nitrogen absorption is low less than 190 nm. Absorbance measurements below 200 nm should be performed in an oxygen-free nitrogen-purged sample container. However, it is recommended to keep the sample chamber vacuumed for values below 185 nm.
While a blank reference measurement provides extremely reliable results, it is recommended to use a cuvette pair with optically matched windows to avoid any absorbance mismatches.
|Optical Glass||340 – 2,500 nm||$$|
|UV Quartz||190 – 2,500 nm||$$$|
|UV Plastic||285 – 750 nm||$|
|Vis Plastic||340 – 750 nm||$|
Conclusion of Cuvette Material
- Each cuvette has an ultraviolet-visible absorbance cut-off. Below the cut-off point, the solvent absorbs light on its own.
- It is expected to utilize only quartz cuvettes for UV absorbance measurements. However, glass, plastic, and quartz cuvettes are suitable for measuring absorbance in the visible area.
- Disposable plastic cuvettes are suitable for investigations requiring high purity as they limit the chance of contamination. Any cuvette can be used for an aqueous solution. However, when organic solvents are used, glass/quartz cuvettes (not glued cuvettes) are preferred since they are more resistant to solvents than plastic cuvettes.
- Although plastic cuvettes can only be reused a few times, they are cost-effective. Because glass and quartz are reusable materials, they may be cleaned and maintained properly to extend their useful life. Quartz transmits more light and is more transparent. As a result, it is used in highly sensitive measurements.
- Additionally, quartz is more heat resistant. At the same time, glass and plastic cuvettes are not optimal for determining concentration and purity.
- Two or four/five sides of cuvettes are polished. The polished side maximizes light transmission. Because light propagates linearly across the sample, polishing two sides is sufficient. Because the signal is received at a 90° angle to the light in fluorescence and scattering investigations, all four sides must be polished.
Step II: Understanding the Path Lenth
Cuvettes are small rectangular containers made of glass or quartz. They are usually designed with a 10 mm path length for the light beam through the solvents, however, the path length can extend from 0.2 or 0.5 mm to 100 mm. The sample cell contains a dilute solution of the solvents being tested.
Image 10mm Cuvettes and Variations
What is Cuvette Path Length?
The distance traveled by light through the sample is known as path length. The length between the inside walls of a UV vis cuvette where light passes through is known as the light path. The inner distance between the front and back windows of a conventional spectrophotometer cuvette will be the light path or path length.
Why is Cuvette Path Length Important?
The path length is chosen to ensure that the detector’s dynamic range is not exceeded by absorbance readings. The chosen path length is frequently the best compromise between the lowest expected concentration and the highest expected concentration. This compromise ensures that the detector’s dynamic range is not exceeded when measuring absorbance values. As a result, you’ll get the best possible measurements.
What is the standard cuvette path length in UV VIS analysis?
The standard and most used cuvette path length is 10 mm. However, UV vis cuvettes that provide a shorter or longer light path through the sample are also available.
Other Available Path Length Sizes
Typical pathlength sizes are 1, 2, 5, 10, 20, 30, 50, and 100 mm. Custom path lengths are available.
Standard 10mm Path Length Cuvettes:
Short (<10mm) Path Length Cuvettes:
Long (>10mm) Path Length Cuvettes:
- Why are “short path length” cuvettes used? (for too concentrated samples)
- Why are “long path length” cuvettes used? (for too diluted samples)
Step III Determining the Cuvette Volume
What’s the standard cuvette volume?
3.5 mL is the standard and most used cuvette volume. The maximum amount of sample that a cuvette can safely carry is called cuvette volume. The most typical capacity for a regular 10 mm cuvette is 3.5 mL, but how do we calculate it?
How to calculate a cuvette volume?
The volume of the cuvette is simple to calculate. On each product page, you’ll find dimension charts that show you exactly what figures you’ll need. The formula we employ is as follows:
Path Length x Inner Width x Inner Height x 80% = cuvette volume
So let’s just take a standard 10 mm spectrophotometer cuvette VFOFO3 as an example. Here is how the formula would look:
10 (PL) x 10 (IW) x 43.75 (IH) x 80% = 3.5 mL
But, hold on, where does the other 80% come from? That’s an excellent question! This is how the formula should be written:
10 x 10 x 43.75 = 4.375 mL
We choose the 80% value because a cuvette should never be filled more than 80% full. This creates a risky situation since the samples can spill if they are too close to the top of the cuvette. Spills on the lab bench, in your machine, or on your skin are all possibilities (hopefully you are wearing gloves).
Is it necessary to fill the cuvette up to 80%?
The answer to this query is dependent on the sort of cuvette you’re using and your machine’s Z Dimension (laser height). As an example, let’s say our spectrophotometer has a Z dimension of 8.5 mm and a 10 mm cuvette. We want the sample to reach a height of at least 12 mm in the cuvette. So, in theory, we’d apply the same volume formula, but with a 12 mm height and no 80% value.
Here is what it would look like:
10 x 10 x 10.75 = 1.075 mL
Note: We get the 10.75mm figure by subtracting the base thickness of 1.25 mm from the 12 mm value.
Do any cuvettes need to be fully filled?
Most cuvettes do not need to be completely filled to work. So, if you have an experiment that requires a small sample size, don’t just go by the cuvette volume listed on our site. You can figure out the best volume by taking the Z dimension of your machine and figuring it out that way.
Of course, there are some exceptions to the rule and some cuvettes do need to be filled 100% to work properly. These cuvettes are our sub-micro cuvettes, and any type of flow through cell. When the sample sizes are as small as 2 -50 uL, you have to make sure there is enough sample in the cuvette for the light to pass through.
Examples of Sub-micro Cuvettes to be Fully Filled
Samples of flow through cells
What is the Z dimension of your Spectrophotometers?
You now know how to compute the volume of any cuvette. If you need to save sample, keep in mind your machine’s Z Dimension. The most used Z Dimensions are 8.5 mm, 15 mm, and 20 mm.
The position of the light beam passing through the cuvette is defined by the Z dimension. When working with sub-micro volume samples, this is a crucial criterion.
When using a sub-micro volume cuvette, it’s vital to place your sample solution in the center of the instrument light beam. Otherwise, it’s conceivable that erroneous or noisy data readings will be taken. Any light source that does not pass through the solution should be blocked (or masked) with a black wall. If the cuvette is not properly veiled, the absorbance sensitivity to measurement may be lowered.
Find various instrument Z dimensions: Z dimensions (Z dim) when Choosing a Micro Cuvette
Step IV Choose the UV vis Cuvette Closures
Our UV vis quartz cuvettes have a spectral range of 190 to 2500 nm. The standard cuvette path length is 10 mm, and the external dimensions are 12.5 mm in width, 12.5 mm in length, and 45 mm in height. 10 mm (width) and 10 mm (length) are the inside dimensions. 3.5 mL is the nominal volume. There are two, three, four, or five windows polished cuvettes available. They can be used with organic solvents (fused and molded types).
Popular Cuvettes and Variations
If you need smaller volume cuvettes, we’ve tested and confirmed that the following cuvettes are compatible with most UV-Vis Spectrophotometers:
Semi-micro rectangular UV vis cuvette, 0.35-1.7 mL volume:
Below you can find a list of cuvettes that vary from 10mm cuvettes from bottom, caps, path lengths, inside widths, volumes, and the number of clear walls or other shapes available for immediate ordering. However, if you cannot find the desired cuvettes, please contact us for customization.
It’s not recommended to use plastic cuvettes in the UV vis spectrometers. Technically, any standard 10×10 mm cuvette can be used, but you should be aware of the material and its transmission profile before doing so. Around 300 nm, even UV plastic cuvettes begin to absorb light and have an impact on the results. Use caution when utilizing normal plastic or acrylic cuvettes. Use the quartz UV vis cuvettes for the best results.
Some more suggestions
- A standard cuvette outer dimensions 12.5 mm x 12.5 mm. The volume of a UV vis cuvette can range from microliters to milliliters. The Z dimensions are usually 8.5 mm, 15 mm, and 20 mm. The standard path length is 10 mm.
- To facilitate efficient temperature and heating control over the sample, the contact area between the cuvette’s wall and the shaft carrying the cuvette should be as large as possible.
- One end of the cuvette is closed. It should be clean and free of pollutants or fingerprints, as impurities might affect a spectrophotometer’s result. At the top, it is open to the atmosphere, while at the bottom, it is sealed. The transparent cuvette should be used. For measurement, cuvettes should be placed in a dark area chamber.
- Cuvettes are fragile and costly. As a result, they must be carefully handled. Scratching cuvettes is not recommended. Wire racks should not be used to store them. They shouldn’t be cleaned with abrasives or brushes, either. For a longer period of time, samples should not be stored in the cuvette. They should be cleaned as soon as possible after use. Cuvettes made of disposable plastic are less expensive.
Things to Remember
When using a cuvette to measure absorbance, there are a few precautions to keep in mind.
- Initially, a blank measurement with a cuvette should be used to calibrate the UV vis spectrophotometer.
- There will be a drop in signal to noise ratio if more dilution is done in a cuvette compartment.
- If measurements below 190 nm are required, oxygen-free nitrogen purging in the sample compartment should be used, or a vacuum should be maintained in the sample chamber if measurements below 185 nm are required.
Cuvettes have the ability to impact absorbance results either directly or indirectly. In UV-vis spectroscopy, selecting an appropriate UV vis cuvette for measuring absorbance and transmittance requires extreme caution. The cuvette’s quality must not be compromised; else, the experimental results will be affected. Obtaining good cuvettes within a budget should also be taken into consideration.