UV-vis Spectrophotometer Cuvette Selection Guide

UV-vis Spectrophotometer Cuvette Selection Guide

  Knowledge of Cuvette (cuvet) Material, Transmission, Z Dimension and Path Length

Also Check Article Spectrophotometer Quartz Cuvettes for UV Range (Bestseller List)

In This Article:

Choosing a correct cuvette for UV VIS range measurements can be crucial for laboratories utilizing. Not all cuvette materials or types will work for every experiment, so some basic knowledge is necessary for the right selection.

Here we aim to help you get a better understanding of important factors to consider when choosing a UV-VIS cuvette. Below is a video for some basic cuvette types.

Cuvettes from the video:

What is a cuvette (cuvet, curvette)? 

A cuvette (French: cuvette = "little vessel") is a small tube-like container with straight sides and a circular or square cross-section. They are usually sealed at one end and have an additional cap to seal the other end.

Standard cuvettes are generally square or rectangular in cross-section to avoid refraction artifacts. Most of them are used in spectrophotometers, luminometers, and fluorometers. 

Other Answers of Cuvette Definition

A small often-transparent laboratory vessel (as a tube) (Source: Merriam-Webster Online Dictionary) 

Laboratory vessel: a transparent tubular laboratory vessel or dish for holding a liquid (Source: Encarta World English Dictionary)

What is a cuvette used for?

A cuvette is a piece of laboratory vial that is used to hold samples solutions for spectroscopic analysis, where a beam of light is passed through the sample within the cuvette to measure the absorbance, transmittance, fluorescence intensity, fluorescence polarization, or fluorescence lifetime of the sample. This measurement is done with a spectrophotometer.

Cuvettes are made from glass, plastic, or optical-grade quartz. Plastic cuvettes have the advantage of being less expensive and disposable and are often used in fast spectroscopic assays. Quartz and glass cuvettes are used when organic solvents are involved, which have higher resistance compared to plastic types. In general, quartz and glass cuvettes display greater transparency and accuracy of measurement, and they can be re-used many times over plastic cuvettes. 

Our Quartz Cuvette Types

Micro/Semi/Macro Volume	Lid/Stopper/Screw Cap
Spectrophotometer Cuvettes	Fluorometer Cuvettes
Single/Dual/Demountable	Tailored Requirements
Flow-Through Cuvettes	Custom Cuvettes

I understand that there are so many types of cuvettes available, how can you choose the right one that fits my experiments? 

What type of cuvette to select? Glass Cuvette vs. Quartz Cuvette? How to Find the Right Cuvette?

There are so many types of cuvettes available in the market and so many factors to consider. How can I find the most suitable one?  In this section we’ll walk through the following subjects to help you a better understanding of different types of cuvettes:

1. Cuvette Materials
2. Cuvette Transmission
3. Cuvette Path Length
4. Cuvette Volume Sizes
5. Cuvette Z dimension (ZD)
6. Cuvette Caps And Bottoms

1. Cuvette Materials

There are many factors that we should consider when choosing a cuvette. And the most important factor when looking for a UV vis cuvette is the cuvette material. Many different materials are available for a cuvette to be made from. 

Below are the most common types of cuvettes, the materials they are made from and their suitable wavelength:

1. Optical Glass Cuvettes

Optical glass cuvettes are suitable for transmission wavelengths from 340nm to 2,500nm (Visible Spectrum).

2. ES Quartz Cuvettes

ES quartz cuvettes for UV light are suitable for transmission wavelengths from 190nm to 2,500nm (UV Spectrum).

3. IR Quartz Cuvettes

IR quartz cuvettes are suitable for wavelengths from 250nm to 3,500nm.

4. Polystyrene (PS) or Polymethyl Methacrylate (PMMA)

Plastic cuvettes are suitable for wavelengths from 380nm to 780nm (Visible Spectrum).

Each of these materials has its advantages and disadvantages, which depend on your application and the budget will determine which one of the above is best. 

Different cuvettes made of different materials

2. Cuvette Transmissions 

1. Let's start with Optical Glass Material.

If you have a tight budget, then you are going to want to go with an Optical Glass cuvette.  This cuvette material is sufficient for work in the visible range and has a decent transmission range from 340-2,500nm and transmission rate of approx. 82% at 350nm of an empty cell. Most applications will fall in this range and many do not need the additional UV range that you get with the quartz materials.

2. ES Quartz is one step above an optical glass type. To pay a bit more for quartz, and you’ll get an extended transmission range of 190-2,500nm. 

These cuvettes have a great transmission rate of approx. 83% at 220nm of an empty cell. For UV experiments, you absolutely need an ES quartz cuvette and it’s highly recommended that you do not try to cut corners here because by getting a cheap UV cell, your data will not be up to par.

3. IR Quartz is an amazing choice for cuvettes for UV-vis range measurements. The transmission range is 220-3,500nm so you get some of the UV, but you get a nice range in the IR as well. The transmission rate of IR Quartz is approx. 88% at 2730nm of an empty cell.

Different Material Transmission Range and Suitable Applications

Transmission of Empty Cuvettes Made of Different Materials

3. Cuvette Path Length

We are continuing to discuss cuvette path lengths. This might be a bit confusing and we want to make sure you have a crystal clear idea of what the cuvette light path is and other information associated with it. 

The following topics about the optical path length of a cuvette will be covered:

1. What is cuvette path length?
2. Light path tolerances
3. Dual cuvette path lengths

What is Cuvette Path Length?

The optical path length of a cuvette is the distance of light that goes through the interior walls of a cuvette. 

On a standard spectrometer cuvette, the light path or path length will be the inner distance from the front window to the back window. The standard cuvette optical path length is 10mm.

Besides standard 10mm cuvette path length, the sizes vary from 1mm up to 100mm. Smaller than 1mm light paths are available but those are for more specialized cuvettes such as demountable cells or HPLC flow cells.

Path Length Tolerances

The industry standard for path length tolerance is ±0.05mm. So in other words, standard 10mm light path length can range in size from 9.95 mm to 10.05 mm.

Cuvettes With Dual-Path Lengths

We have a series of 4 window clear cuvettes that can be used for short and long path lengths at the same time. For example, 0.7mL volume cuvette with a path length of 2 mm AND a standard 10 mm all rolled into a single piece.

Dual-Path Length Cuvette

Basically, depending on how you put the cuvette in your spectrophotometer will determine which path length is used. If the light beam enters the front window, then you have a 10 mm path length cuvette. If you rotate the cuvette 90 degrees you have a 2 mm path length. 

We have a few different cuvettes with dual-path lengths available such as:

• 10x1 mm
• 10x2 mm
• 10x3 mm
• 10x5 mm

Check out the site for a full list of cuvettes available: https://airekacells.com/cuvettes

4. Cuvette Volume Sizes

Another factor for choosing the right cuvette is the volume size. The cuvette volume is the maximum amount of sample that a cuvette can safely hold.

The most common capacity is 3.5 mL for a standard 10 mm cuvette cell, but have you thought about in what way do we figure it out?

How to Calculate Cuvette Volumes? 

Calculating the volume of any cuvettes could be as simple. Here is a dimension chart on some products to help you quickly figure out common cuvette volumes.

Check out the formula that we use:

Inner Length x Inner Width x Inner Height x 80% = cuvette volume

Let’s just take a standard 10mm spectrophotometer cell QG10004-2 for example: 

10mm (L) x 10mm (W) x 43.75mm (H) x 80% = 3.5 mL

Wait a second! Why is the 80% applied? Great question! The full volume of the cuvette should be 4.375mL:

10mm x 10mm x 43.75mm= 4.375 mL

The reason we use the 80% is that you should never fill up a cuvette over 80%. When the samples are too close to the top of the cuvette (>80%), they could easily spill which causes much trouble during experiments.

Furthermore, Should I Always Fill the Cuvette to 80% In Volume?

The answer to this question depends on what type of cuvette you are using and the Z dimension (laser height) of your instrument. 

If the Z dimension is 8.5mm, the sample should be at least 12mm height to cover the laser height. For example, QG10004-2, the least volume should be 10.7-3.5mL:

10mm x 10mm x (12mm-1.25mm)≈10.7mL

If the Z dimension is 15mm, the sample should be at least 19mm height to cover the laser height. Again for QG10004-2, the least volume should be 1.8-3.5mL:

10mm x 10mm x (19mm-1.25mm)≈1.8mL

Note: We subtract the base thickness of 1.25 mm from the 12/19mm value.

Any exceptions? Any Cuvettes to be Fully Filled?

Yes, of course! 

For sub-micro quartz cells or flow-through cuvette cells, when the sample sizes are small enough to 10-400uL, you need to make sure there is enough sample held in the cuvette for laser light passing through.

Now you are an expert on how to calculate the cuvette volume of any cuvettes. Next let's turn to cover more details of Z dimension below, which is important when choosing sub-micro cuvettes with low volumes from 10-200uL. 

5. Cuvette Z dimension (ZD) or Z height (ZH)

What is the Z dimension of a spectrophotometer cell/cuvette?

The Z dimension of a spectroscopy cuvette/cell is the distance from the bottom of the cuvette to the center of the sample window or aperture (the area through which the light passes). 

Z dimension is usually used with small volume cuvettes or flow-through cells when there is a restricted area window aperture.

Why is Z Dimension important?

It is essential to make sure that you order the cuvette with the correct Z dimension. 

For example, you order a QG15100-4, 100uL sub-micro quartz cell, with a 15mm Z dimension. The window is only 5mm height and when using it to 8.5mm Z dimension instrument, the laser light source cannot go through the window and you'll have a 0% light transmission.

Why does Z dimension vary between different instruments?

Each instrument manufacturer makes engineering decisions for the design of their instrument to assure that it performs optimally. The height, width, focus, and placement of the light beam in any instrument is based on the optical and engineering decisions taken to ensure that the instrument performs to it's published specifications.

Where can I find the Z dimension of my instrument?

The correct Z dimension or Z height or center beam height for an instrument should be detailed in the literature supplied by the manufacturer with the instrument.

If you are not sure, please send us an email (sales@airekacells.com) so to help determine the Z dimension of your instruments.

6. Cuvette Caps And Bottoms

Many different types of caps and bottoms are with different cuvettes to fit your specific experiments. It could be confusing for the researcher when making purchase decisions. 

1. Different spectroscopy cuvette caps are available for different budgets and sealing requirements.

2. Cuvette Bottoms

Flat bottom and Round bottom cuvettes are available with AirekaCells. Round bottoms are usually used with spectrophotometer cuvettes. For most of flow cell and fluorescence cells, the bottoms are flat.

Let's turn back to the question:

What type of cuvette to select? Glass Cuvette vs. Quartz Cuvette? How to Find the Right Cuvette?

For the photometric experiments of liquid samples, the solution must be placed into the standard choice of a sample cuvette.

The distance between the optical windows is accurately predefined; in this way, the path length of the sample inside the cuvette is known.

The selection of different types of cuvettes is more than expected, even those cuvettes that are used for absorbance measurements in the area of UV-Vis spectroscopy.

The most common type of cuvette is square, with external dimensions of 12.5x12.5mm. This size accommodates sample volumes from the microliter (sub-micro cuvettes)  to semi-micro to the milliliter range (standard volume cuvettes) or even larger.The standard path length of a cuvette is 10 mm, and cuvettes that provide a shorter or wider light path are also available. In addition, cuvettes differ with respect to their material, their height and the size of their measurement window.

We’ll now walk through the factors to consider when making the purchase. The decision about which type of cuvette to choose will depend on 1) the instrument used, on 2) the nature of the application and on 3) the properties of the sample.

Step 1: Outer Dimension

The cuvette outer dimension has to fit into the instrument cuvette shaft.

The selection of the equipment necessitates requirements on the cuvette since it must be compatible with the device. This pertains mainly to the outer dimensions of the cuvette, as it needs to fit into the cuvette shaft, but the height of the measurement windows is also crucial.

Check above [3. Cuvette Path Length] if you are not sure.

Step2: Z dimension

The cuvette Z dimension must fit into the instrument laser light height.

This consideration is particularly important for cuvettes that are designed to measure small volumes and that therefore feature very small measurement windows. Common heights of light paths are 8.5 mm, 15 mm and 20mm.

Check above [5. Cuvette Z dimension (ZD) or Z height (ZH)] if you are not sure.

Step3: Wavelength Range

The next important factor concerns the measuring wavelengths.

Standard cuvettes made from PMMA, polystyrene or normal glass are only transparent in the visible range. If wavelengths in the UV-range, below approximately 300 nm, quartz cells or a special type of plastic, which provide sufficient transparency in this range, must be used.

It is generally important that cuvettes be as transparent as possible for the wavelengths to be measured so not to limit the available linear range of the spectrometer.

Check above [1.Cuvette Materials b. Cuvette Transmission] for more details.

Different Material Transmission Range and Suitable Applications

Step4: Cuvette Volumes

When experiments measure absorbance over time, heating and efficient temperature control of a sample during the measurement process is crucial for those that rely on reactions that occur at a certain specific temperature.

In addition to an appropriate level of resistance of the material, it is important in this case that the contact area between the wall of the cuvette and the temperature-controlled cuvette shaft is as large as possible.

For these reasons, certain cuvettes, such as macro-cuvettes, provide an advantage in temperature-controlled applications.

Step5: Disposable Plastic or Reusable Quartz/Glass Cuvettes

If only a small amount of sample is available, one might consider re-using the sample for the following measurements. In this case, single-use plastic cuvettes are recommended. Plastic cuvette will minimize the risk of contamination.

If, on the other hand, organic solvents are involved, glass quartz cuvettes are the preferred choice as these display higher resistance compared to variants made from plastic.

In general, glass cuvettes display greater transparency and accuracy of measurement, and they can be re-used many times. Since plastic cuvettes are only used once and do not require cleaning, possible damage and loss do not have to be taken into account.

Step6: Fluorescence Cuvettes

Fluorescence cuvettes for fluorometers have 3 or 4 walls transparent while spectrophotometer cuvettes have 2 walls clear.

The QG10204-4 quartz cell is the most basic cuvette for UV VIS measurements. This cuvette has all four windows polished and comes in the UV grade quartz. Like spectrometer cuvettes, there is round bottom alternative in our fluorescence line.

Step7: Custom Cuvettes

If the cuvettes listed on our site do not fit into your requirements, then email us for customizing any of the hundreds of cuvettes from our product line to produce exactly what you need. Email us (sales@airekacells.com) your graphic design so that we could tailor the product to your exact needs.

Step8: Make a Decision

Now you have all the basic information to correctly choose a great cuvette for UV VIS experiments. All that is left to make to decision and find the right cuvette for your experiments.

Have fun!

What's Next>>

Check Article Spectrophotometer Quartz Cuvettes for UV Range (Bestseller List)

Our Quartz Cuvette Types

Micro/Semi/Macro Volume	Lid/Stopper/Screw Cap
Spectrophotometer Cuvettes	Fluorometer Cuvettes
Single/Dual/Demountable	Tailored Requirements
Flow-Through Cuvettes	Custom Cuvettes