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How to Clean Laboratory Glass Cells / Cuvettes so that they Last Longer

Written by Janice M on . Posted in Colour Measurement, Technical Tips

If you would like to achieve accurate and repeatable measurement results from colorimeters, photometers or spectrophotometers, it is vital to make sure that the glass cells (also known as cuvettes) are well cleaned, because fingerprints and dirt can lead to large errors.

Precision glass cells are also expensive because they are especially made with a high quality optical glass, to provide even thickness and transparency for accurate scientific measurements, so taking good care of them will help them to last longer.

A Lovibond® precision made optical cell

This method can be used for other laboratory glassware, too.

Materials required:

Decon 90® cleaning agent
Hot and Cold running water into suitable sink
De-ionised water
Ultrasonic cleaner
Temperature controlled circulatory drying oven
pH meter
Bottle brushes to suit
Protective rubber gloves and goggles

Method:

  1. Lightly soiled items can be immersed in a solution of 5% Decon 90® and hot water, and brush cleaned by hand (wearing protective gloves). Using a hot solution increases the effectiveness of the cleaning process.
  2. Heavily soiled items require a more concentrated solution, sometimes requiring 100% Decon 90®. As before, these are brush cleaned by hand.
  3. Stubborn contamination may also require cleaning in a hot solution (40°C to 50°C) in an ultrasonic bath for approximately 15 minutes. This process can be repeated as required although the solution should be changed when the pH drops below pH 8.5.
  4. Three stages of rinsing follow. Firstly under running hot water, then under running cold water and finally rinsing all surfaces thoroughly with de-ionised water. It is particularly essential to use de-ionised water for spectrophotometer cells or cells that are to be inserted into measuring equipment to avoid any watermarks. Shake gently to remove surplus water.
  5. Drying. The cleaned items are then placed in a hot air circulatory oven at 80°C until dry. Cells and glassware should be inverted to aid the removal of moisture. On removal from the oven, all cells should be inspected for glass clarity. If not satisfactory, the cleaning process should be repeated.
  6. Throughout the cleaning process, laboratory personnel should wear adequate protective equipment to avoid any unforeseen hazard.

Stained Cells:

  1. Ultrasonic Method. Place cells in an ultrasonic cleaner at room temperature.
    OR
  2. Soaking Method. Immerse the cell in freshly prepared chromic acid and leave overnight. Do not allow the cell to dry out before rinsing with distilled water and follow with an ethanol rinse. Allow to dry.

3 Important Tips to Note:

  1. Maximum temperature recommended is basically the upper end of hand-hot: if it hurts to wash it, the water is too hot.
  2. NEVER try to clean a cell by pushing a cloth down inside it because you can easily crack the face.
  3. STORE the cells in fitted cases, so that they stay protected from breakage.

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