Because we have to raise our solutions to high temperature we sometimes have evaporation and therefore sticking of the organic molecules, DNA, polymerase, etc. to the inside surfaces of the quartz cuvette. What is the best way to remove this without leaving residue or scratching or otherwise damaging the cuvette?
acid wash (2M HCl or 2M HNO3) and then thorough rinsing with milli-q water. Solvents are good for final washing but they have to be very pure. After washing away acid, use glass distilled acetone and air dry in dust free place
acid wash (2M HCl or 2M HNO3) and then thorough rinsing with milli-q water. Solvents are good for final washing but they have to be very pure. After washing away acid, use glass distilled acetone and air dry in dust free place
A 5-10 min. soak in concentrated nitric acid (HNO3) usually works well for me. In addition you could try the cuvette cleaning agent Hellmanex (http://www.hellma-analytics.com/text/197/en/hellmanex%C2%AE-iii.html) at a concentration of 1-2%.
to remove protein which is still sticking in the cuvette you might want to use trypsin (I just used the left over trypsin from cell culture); incubate over night at room temperature. then just wash the cuvette with H20 and finally flush it with ethanol
It's a bad idea to start washing the cuvette with ethanol after using it with solutions containing protein. Glass gets stained with protein precipitate which may be hard to remove. As Heide Roth suggested, it's best to use ethanol for the final rinse, after washing the cuvette with a good amount of deionized H2O. Same thing with acetone, it will cause residual salts from the buffer solution to precipitate on the glass, which does not make it cleaner.
Thanks a lot for all the recommendations. I gather, as Alexander summarizes, that the consensus, with regard to protein and DNA, is to first wash with deionized water and then with ethanol or acetone. Does anyone have any definite preference as to which of the latter two, ethanol or acetone, is cleaner?
Wash with nitric acid (50% is good too) for 10 mins. Carefully remove the acid. Then wash 3 times with milliq water. Finally rinse with acetone, remove excess and let the cuvette air dry.
When I worked in analytical laboratory we used cleaning solutions with: Potassium dichromate + Distilled water + Sulfuric acid like this one
http://library.med.utah.edu/WebPath/HISTHTML/MANUALS/ACIDGLAS.PDF
CUVETTE CLEANING SOLUTION 4: GOOD FOR PROTEINS
To remove protein which is still sticking in the cuvette you might want to use trypsin (I just use the left over trypsin from a cell culture); incubate over night at room temperature, wash the cuvette with H20 and finally flush it with ethanol.
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