Page 10 - Catalogue - cuvettes and solid-state calibration standards

Choosing the right cuvette

1. Absorption or fluorescence measurement – which cuvette do I need?

 If you’re using a spectrophotometer, you’ll need a cell with two polished (optically transparent) windows
that are parallel to each other and located on opposite sides of the cell. In this case, the light beam enters
the cell through the front window and leaves it through the back one in a straight line. For fluorescence
measurements the cell needs three or four polished windows.

2. What if I need to measure both, absorption AND fluorescence?

 Due to the number of optically polished windows a fluorimeter cell will work in a spectrophotometer - the
other way round will not work.

3. Which material should I choose?

 Technical data for our optical glass, UV and IR quartz are shown in the section Materials and Transmission
Characteristics. In addition to the required wavelength range the price may also play a role. For example, if
you only measure in the visible range then an optical glass cell is sufficient. If, however, you occasionally
also measure in the IR range, then we recommend an IR quartz cell as it covers both areas.

4. What lightpath do I need?

 The lightpath is the distance that the light beam travels between entering and exiting the cuvette chamber.
We offer cells ranging from 0.01 to 200 mm. The deciding factor is the amount of sample available. If it’s
relatively unlimited then a cell with a larger lightpath is easier to fill and handle. 10 mm cells have become
the “industry standard”. However, if you only have a very limited amount of sample, for example DNA/RNA,
then you should choose a cell with a correspondingly short lightpath.

5. What volume should the cell have?

 In general, the volume is dependent on the lightpath – the longer the lightpath, the larger the volume.
However, we also offer low-volume cells with a lightpath from 1 to 100 mm. If you have to work with a
predetermined lightpath but only have a limited amount of sample, you’ll still find a suitable cell here. We
offer the following cell types:

macro • semi-micro • micro • sub-micro • ultra-micro (Micro Focus Cell – for DNA samples)

6. Rectangular or circular?

 90% of all cuvettes sold are rectangular. But if your instrument has a circular holder, for example a
polarimeter, we also offer a wide range of circular (cylindrical) cells.

7. What type of cover should I choose?

 The simplest cover is the PTFE type that sits loosely on the cuvette and stops contaminants entering it
from above. These lids are NOT airtight.

 The PTFE stopper offers air-tightness and allows the contents of the cell to be mixed by shaking or turning
it upside down.

 Screw caps provide the best seal and, hence, are also suitable for anaerobic work.
 Graded seal (quartz-to-glass) tubes – please see question 8.

8. What if I need to modify or enhance the cell by adding a further piece of glass apparatus?

 In this case you’ll need a cuvette with a graded seal tube. We recommend using Pyrex® for the part to be
connected. Your glass blower can offer further information on the suitability of other types of glass.

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All prices are shown in Euro and are subject to VAT where applicable.