Practical tips for using cuvettes correctly
The cuvette in the laboratory is one of the most important components in turbidity measurement. They are used to introduce all measurement objects, whether samples or standards, into the optical path of the turbidimeter. In order to always get accurate measurement results, there are some basic rules for handling cuvettes.
The cuvette is usually made of special optical glass, which has little influence on the measurement. Nonetheless, there are important factors to consider to avoid errors caused by the cuvette.
Careful cuvette handling
Any cuvettes with obvious scratches should be discarded. Especially after washing with tap water, the cuvette should also be carefully rinsed with deionized or distilled water and dried in the air. This prevents destructive calcium deposition in and on the test tube. Also, it is recommended that the cuvette be washed with dilute hydrochloric acid from time to time.
The cuvettes should be separated, covered and stored to avoid contaminating the inside or outside. In particular, avoid storing multiple cuvettes in containers without separation. There is a risk of scraping each other. Only handle the cuvette on the lid to avoid leaving fingerprints on the glass.
Proper cuvette preparation
Before measuring with a cuvette, you must always ensure that its inside and outside are clean. If introduced into the cuvette chamber of the turbidimeter along with the sample, it must also be externally dry and free of any contamination.
Hanna Instruments found that using silicone oil to fuel the cuvette makes sense, especially for very low turbidity measurements. It has the same refractive index as the cuvette, so it does not adversely affect the measurement. On the contrary: A very thin layer of silicone compensates for the smallest defects in the cuvette, resulting in more accurate measurements. The easiest way is to gently rub with a little oil on an oil-free cloth and then wipe with oil.
After processing, the cuvette should appear almost dry and no residual oil should be visible. Upon completion, a visual inspection of the dust particles is recommended. Linoleum can be picked up for future treatment. However, store it in a sealed bag to avoid contamination.