3
$\begingroup$

The lab I started working in has a spectrophotometer with cuvettes. The cuvettes need to be inspected and cleaned regularly. The senior people in the lab are in disagreement as to the correct procedure for cleaning them. Some recommend soap and a bristle brush with running water, others just suggest leaving them to soak in an ethanol solution.

The question is twofold;

a) Is there any risk that the brush will scratch the glass?

b) Is there any advantage to the soap method? If not, I am wasting an hour of my boss' time and money.

Improve this question
$\endgroup$
2
  • $\begingroup$ I would think the thing to do is to consult the manufacturer of the cuvettes... $\endgroup$
    – Zhe
    Commented Sep 26, 2017 at 14:33
  • 1
    $\begingroup$ Not sure what kind of cuvettes you are using, nor what types of solutions you are using. I'd agree with andselisk. No abrasives also meaning no brush which can hold grit. If you're using the square UV/Vis cuvettes with a thin quartz window then I'd certainly stay away from a brush. My thought if the cuvettes are really cruddy, then I'd soak them in a acidic chromate cleaning solution. $\endgroup$
    – MaxW
    Commented Sep 26, 2017 at 15:01

2 Answers 2

Reset to default
3
$\begingroup$

I always managed to wash out the remaining solution with the corresponding solvent a couple of times, subsequently rinsing with acetone/isopropyl alcohol and leave it dry on air for a few minutes. The method of spectrophotometry requires that you are using homogeneous solution anyway, so there shouldn't be any precipitation/deposition, otherwise you cannot interpret the data with Beer-Lambert law.

Also, don't soak cells in KOH-bath or similar alkaline media. And I'm always strongly against abrasives, especially when it comes to cleaning optics. Even quartz cuvettes can be occasionally damaged with the brush pick. Disposable PS-cells can be easily scratched. Plus, there is a little risk of hydraulic pressure knocking out the cuvette's bottom (like it happens with test tubes when cleaned too vigorously). Leave mechanical cleaning for the professors of mechanics *.

*From a story published in The Oxford Book of Scientific Anecdotes:

Victor Moritz Goldschmidt, a distinguished geochemist, was reputed to have carried a capsule of potassium cyanide when he was planning his escape from Nazi Germany. When a friend in the engineering department of the university expressed interest, Goldschmidt was supposed to have replied that cyanide was for professors of chemistry; his friend, a professor of mechanics, would have to carry a rope.

Improve this answer
$\endgroup$
0
$\begingroup$

Clean sample cells, ATR surfaces etc are imperative in spectrometry and a real problem. My ultimate solution was to buy my exclusive sets of cells and use only one of the set for sample and one for reference and not run an analysis until single beam and double beam matched archive spectra. NO ONE else ever touched these. Today with disposable cells, pipet tips, etc. contamination is a bigger problem than appreciated. It depends on the material but simple rinsing might not be sufficient. I used a "clean" detergent[pure sodium n-lauryl sulfate works good] with a fine brush and 18meg water after an appropriate organic solvent rinse and it usually worked but blanks should be run before each analysis.

Improve this answer
$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.