AnsweredAssumed Answered

UV Impurity Value

Question asked by camelia on Mar 25, 2020
Latest reply on Mar 31, 2020 by ryoboyle

Hi All,

I'm using Openlab 2.3 and would like to know how to use the UV Impurity Check and interpret the UV Purity value. I have researched this forum and the Help and Learning but still feel I am lacking an understanding or clear methodology.

I apologise for the number of questions which I have detailed below. Any advice would be much appreciated. 


1. Is the colour flag to be used as - no impurities detected (green) impurities detected (red)?

2. What does a 0% threshold value actually mean?

3. What other settings can be used alongside the threshold value for the Impurity Check?

4. Can Background correction be used with the Impurity Check and how is this set up?

5. What does the Ratio plot represent?

6. Where do you set the match factor for UV confirmation?

7. Is the Impurity value to be treated in a similar way to the Match factor ie

Match factor >995: Spectra very similar

995 > Match factor >990:There is some similarity

Match factor < 990: Data should be observed carefully

8. I have run pure standards in methanol and collected data between 190-300nm. I have used the impurity check on these standards and the returned Impurity value was <500 and the threshold value had to be set to 0% to return a green flag.

As the UV cut off for methanol is 210nm and i'm collecting spectra below this at 190nm could this explain why the impurity check on the standards is <500 due to the absorbance or impurities in the solvent?

9. In a previous post (Spectral Evaluation on OpenLAB CDS 2.1), a method for evaluation UV impurity of samples is suggested as - first running the standard, adjusting the threshold so that the peaks are shown as pure, then using these settings to analyse samples. What I want to do is assess the purity of the standard - what method should I adopt to do this?

10.Do Agilent offer any on-line training in Spectral Evaluation that I could access?


Many Thanks