The cuvette holds the sample and the cuvette is placed in a spectrophotometer for spectral analysis, but the world of cuvettes can be an expansive and confusing world, and you may get confused about which cuvette is to use for your experiment. In this article, we present the basic material requirements, and then we will draw a contrast between different types of cuvettes to help you select the right cuvette.
7 Things to Think About When Ordering a Cuvette
In this article:
1. What material do you need?
2. What kind of cuvette do you need, spectrophotometer or fluorometer cuvette?
3.What path length do you need?
4.What cuvette Z-Dimension do you need?
5.What capacity do you need?
6.What kind of cover do you need?
7.Do you need custom cuvettes?
When you are a freshman about spectrophotometer or fluorometer experiments, you may get confused about cuvette selection, then you google ‘How to choose the right cuvette?’, almost all the answers show you the cuvette material is the most important thing because UV rays can’t go through most glass cuvettes but can go through the quartz cuvette.
Cuvettes on market usually manufactured from plastic, glass, quartz, there are different cuvette made from different materials below.
1.What material do you need?
It highly depends on the wavelength and solvents characteristics type you work with when measuring the sample.
Cuvettes are usually made of different transparent materials, such as optical glass, quartz, sapphire, or optical plastic. Each material has unique light-passing properties and it is important to know about such optical characteristic properties before you select the cuvette material.
There are the most common types of cuvettes below, the materials they are manufactured from and their suitable wavelength:
1. Optical Glass Cuvettes
This cuvette material is suitable for the visible spectrum and has a decent transmission range from 340-2,500 nm.
2. UV Quartz Cuvettes
For UV-VIS absorbance studies, you absolutely need a UV quartz cuvette, if you cut corners here by getting a cheap glass or plastic cell, your data will be inaccurate, it’s not recommend to do.
3. IR Quartz Cuvettes
The transmission range on IR Quartz is 220nm to 3,500nm, it is a good choice for UV VIS measurements.
4. Polystyrene (PS) or Polymethyl Methacrylate (PMMA)
The transmission range on PS or PMMA quartz is 380nm to 780nm (Visible Spectrum). Most applications will fall in this range and many do not need the additional UV or IR points that you get from the other materials.
Transmission Range and Suitable Applications of Different Materials
|Optical Glass (G)||340-2500nm||82% at 350nm||Reusable||Visible Range|
|UV Quartz (UV)||190-2500nm||83% at 220nm||Reusable||UV-Visible Range|
|IR Quartz (IR)||220-3500nm||88% at 2730nm||Reusable||UV-Visible-IR Range|
|PS or PMMA||380-780nm||80% at 400nm||Disposable||Visible Range|
Each of these materials has its advantages and disadvantages. Again depending on your application will determine which one of the above is best.
Quartz material has the highest transmission and temperature resistance, most importantly is transparent in both the visible light and UV range, and is a great choice when measuring samples in the UV-light spectrum.
Glass and plastic materials are normally transparent to visible light (380-780 nm) but absorb in the UV (190 – 340 nm) wavelength ranges. Therefore, plastic and glass cuvettes are ideal for colorimetric protein assays or measurement of the bacterial culture density, but cannot be used for concentration and purity measurements of samples in the UV ranges.
It is important that the cuvettes have as high transmission as possible for certain measured wavelengths, but if you have a tight budget and only test the samples in Visible light, then you are going to want to go with a Plastic or Optical Glass cuvette. Plastic cuvettes are low-cost and disposable.
Transmission of Different Materials in Empty Cuvettes
Cuvettes can be made of different materials, and they also can be assembled with different technics, such as Glued, Powder fused, or all fused.
If the sample is an aqueous solution, it can work with most plastic or glass or quartz cuvettes even the NRC glued cuvettes, then you can jump to cuvette type part directly; but if it is organic solvents, you’d better read the next Working Samples section first.
An ideal cuvette material would be transparent to the target light beam and does not interact with the samples used in the measurement.
The material from which the cuvette is made is relatively less important when the sample is an aqueous solution. Plastic or Glass or Quartz cuvettes will all work, and you can even use the most affordable URC glued cuvettes.
If the sample is organic solvents, it’s better to choose more robust cuvettes than the plastic ones, such as the Glass and Quartz cuvettes.
And you should go with chemical resistant fused (CRF) or high-temperature-resistant (HTR) versions rather than the non-resistant to chemicals (NRC) because the NRC cuvette is assembled with glue, benzene, ethanol, corrosive solutions, or other similar attribute solvents may cause the cuvette to leak because it degrades the bonds between the pieces.
2. Which kind of cuvette do you need, Spectrophotometer or Fluorescence cuvette?
It depends on the Laboratory Apparatus you will use.
Spectrophotometers Cuvettes are cells that have 2 parallel sides optical transparent. And the light beam comes in from the front window and exits the back window of the cuvette in one straight line.
The best-selling cuvettes for UV VIS Spectrophotometer measurements in our cuvettes line are our QS20-02, and QS37. Now QS20-02 and QS37 are pretty much identical. The only difference is that QS37 cells have square corners and Type 5 cells have rounded corners. Please see the photo below.
These cuvettes are the ultimate balance for someone looking for a high-quality UV quartz cuvette. You get the affordable full range of the UV quartz material, the price of $12.3 for QS2002 is making it a great buy for labs on a budget.
There are some basic spectrophotometer quartz cuvettes, generally speaking, the rounded bottom one costs less than the square bottom one for the same cuvette type. And you can click here for more spectrophotometer cuvette.
Fluorescence cuvettes are cuvettes that have 4 optically polished walls (some specialized types of cuvettes have 3 transparent walls)
The most basic fluorescence quartz cell for UV VIS measurements is QS22-02. This cuvette has all four windows clear and comes in UV-grade quartz.
There are some basic fluorometer cells, like spectrometer cuvettes, a round bottom is also an alternative in our fluorescence line. And you can click here for more fluorometer cuvette.
3. What path length do you need?
The max path length you can use depends on the laboratory apparatus, and the other factors including sample characteristics, volume availability, levels of concentration, and types of measurements to be made will affect the decision when choosing the appropriate path length of a cuvette for your applications.
For a standard spectrometer cuvette, the light path or path length is the distance between the interior walls of a cuvette where the light goes through, which refers to the inner distance between the front window and the back window cells. Cuvettes come in a large variety of pathlength. The most common path length of cuvettes is 10 mm.
Besides standard 10mm cuvette path length, we also offer path lengths ranging from 1mm up to 100mm. Smaller than 1mm light paths are also available but those are for more specialized cells such as demountable cuvettes or HPLC (High performance liquid chromatography) flow cuvettes.
When taking sample measurements found at low concentrations — for example, RNA, single-stranded DNA, and oligonucleotides — it’s recommended a long enough path length for the data readings are within the linear measuring range of the instrument.
As we all know, higher concentration solutions must be either diluted or using a cuvette with a shorter path length to simulate the dilution. Known from the Beer-Lambert law, A light path of 1 mm cuvettes will allow dsDNA concentration to be as high as 1,000 µg/mL.
It’s a piece of good news that cuvettes with an optional path length are now available with us, it can roll small volume path length such as 2 mm and a standard 10mm into one.
4. What Cuvette Z-Dimension do you need?
Depends on the Z-Dimension of the machine, where the light beam comes out.
The z-dimension of a spectrophotometer/fluorometer cuvette/cell is the distance from the cuvette base to the center of the sample window or aperture.
Typically, this Z-Dimension, ZD or center height of the cuvette window will have one of the three heights: 8.5mm, 15mm or 20mm.
It is very crucial to make sure that the cuvette you order is right to the light beam, especially when you’re going to order a sub-micro cell.
For example, if you order a QM25-15, 10ul sub-micro cuvette, with 15mm z-dimension, when using it to a 8.5mm ZD machine, the light beam will shoot too low and miss the sample chamber giving you 0% light transmission.
The correct Z dimension or Z height or center beam height for your device should be detailed in the literature supplied by the producer with the instrument. And you can also hop on over to the right tables to check the ZD of your spectrophotometer device.
But if you are still not sure, you can call the instrument manufacture up or send us an email (firstname.lastname@example.org) to find out the Z dimension of your instruments.
5. What capacity do you need?
The cuvette capacity is dependent on the path length awfully. Usually, the larger the path length, the larger the capacity of the cell.
Cuvette capacity is the maximum amount of sample that a cell can safely hold. For a standard 10mm cell, the most common volume is 3.5mL. We can easily to calculate the volume of any cuvette using this formula:
cuvette volume = Inner Length (IL) x Inner Width (IW) x Inner Height (IH) x 80%
Let’s just take a standard QS37, 10 mm spectrophotometer cuvette as an example, to calculate the maximum volume of the cuvette. Here is how the formula would work:
10(IL) x 10(IW) x (45-1.25)(IH) x 80% = 3.5 mL
Note: We need to subtract the base thickness 1.25 from the cuvette size value, and the inner length and width should subtract 1.25*2 because of the double piece.
The reason we use the ‘80%’ is because we should never fill up a cuvette over 80%, or it will take an enormous risk to spill because the samples are too close to the top of the cuvette.
But there is an exception! For a sub-micro quartz cell or flow cuvette, and the sample you use is small enough to 10-400uL, then it’s crucial to make sure there is enough sample in the cuvette for the laser light to pass through.
So, must I fill the cuvette to 80% if I use the standard 10mm, 3.5ml cuvette?
If you taking our QS37,10 mm cuvette, and your spectrophotometer has a ZD of 8.5mm. You want to make sure that the sample reaches at least 15mm high in the cuvette. So, we will use the same volume formula as above, but change the height to 15 mm and leave out the 80% value.
10 x 10 x (15-1.25) = 1.375 mL
Side note: We subtract 1.25 from the 15 value.
Here are the volume sizes offered by ecuvettes.com, We have dimension charts on each product page that show you exactly what figures you need.
6. What type of cover do you need?
There are many types of cuvette covers. Blow are the basic cuvette covers we supplied in ecuvettes.com.
- PTFE Lid – It’s Just a cover that sits on top of the cell. This is not suitable with experiments that require an air-tight cuvette
- Silicone Lid – It has a better seal than the PTFE lid, and allows you to inject samples into the cuvette chamber.
- PTFE Stopper – This is for people who need a better seal than just a standard cover. The PTFE stopper is compatible with airtight measurements and the cuvette with stopper can be shaken or turned upside down to help mix the contents.
- Screw Cap – This caps have the best seal. Our screw caps with Septum allow you to use this type of cuvettes for anaerobic works and other airtight experiments.
7. Do you need custom cuvettes?
If the cuvettes listed on ecuvettes.com 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.
Here are some customize cuvettes from other clients produced in our cell line, and you can click here for more custom cuvettes.
Due to the particularity of customization, Email us (email@example.com) your graphic design so that we could tailor the product to your exact needs.
Quick Centre Height / Z-Dimension Finder Chart:
Here’s our expanding list of z-dimensions for the spectrophotometer. If you have any suggestions or additions, please contact us at firstname.lastname@example.org.
Manufacturer Z-Dimension ABX 8.5mm Agilent 15mm or 20mm Amersham Biosciences 15mm Aminco 15mm Analytik Jena 8.5 or 15mm Baird 12.5mm Beckman Coulter 8.5mm (mostly)- some models 15mm Bio-Rad 8.5mm Bio-Systems 8.5mm Bio-Tek Instruments 15mm Biochrom 15mm Biotecnica 8.5mm Boeco 15mm Braic 20mm Bruins Instruments 15mm Camspec 15mm Cecil 15mm Ciba Corning 8.5mm (mostly)-some models 15mm CGA 8.5mm Dr. Lange 8.5mm Drake 15mm Eppendorf 8.5mm or 15mm Femto 8.5mm GBC 15mm Hach 15mm Hewlett Packard 15mm Hitachi varies Hoefer 15mm Implen 15mm Jasco 12mm Jenway 15mm Krüss AG 8.5mm Macherey-Nagel 15mm Malvern 8.5mm Ocean Optics 15mm Perkin-Elmer 15mm Pharmacia 15mm Riele 8.5mm Safas 8.5mm Sartorius 15mm Scinco 15mm Shimadzu 15mm Spectronics 8.5mm StellarNet 15mm Technikon 15mm Thermo Spectronic 8.5 or 15mm Transasia 8.5mm Turner 8.5mm Varian 20mm Zeiss Specord (15mm), Spekol (8.5mm)