Analytics for Chemistry, Biology and Production:

It is never too late to mend. - It is the first step that is difficult.  -late 16th.


Peter ForsterHome The author of this page is independent and has no commercial intention in mind ! Diese Seite in Deutsch.


Spectroscopy:

The bad example (from the year 1983), to measure a sample in a unbuffered solvent!

Our historical Sample: The same mistake we never did again!
What you see here is tha same sample (from the same/identical bottle) in the "identical" solvent:  Ethanol with the quality label - UVASOL. - It means special medaled produced for spectroscopy -, once from a fresh opened bottel of Lot A, and once from a fresh opened bottle of Lot B, but all from the identical supplier!
And finaly you see the spectrum of the same sample in a mixture of Ethanol/Buffer pH 4.65 (1:1):

                     - (The only spectrum, that can be reproduced again and again in exact the same precision!!!)
Bad_Example
Can you imagine, how wrong your concentration result would be, calculated as usually at Lambdamax. of 654 nm, if you did the calibration in Alcohol from Lot A and your sample measurement in Alcohol from Lot B ?
That's why “old” spectroscopist are telling you, you must measure your reference and your samples not only in the same solvent, they are telling you, you must prepare enough solvent for both measurements and do all time both measurements together !
As you now know , they are completely wrong !   But you have to learn, to think in spectra !
Go back to Spectroscopy


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