Relative response in different detectors

[tom jupille]

lmh beat me to it, but I would not expect to see the same relative response on two systems of different bandwidths.

[Mattias]

You are right - I would be quite lucky if I got the same response difference on two detectors.

It is taken care of in the new version of the method! Thanks for your input.

[Chromatographer2010]

lmh is absolutely correct and in addition on PDA detectors there is a resolution value which typically indicates how many diodes are being averaged for a given wavelenth that has an affect similiar to bandwidth.

In terms of what you are doing for the quantitation of the unknown peaks, your relative quantitation will be accurate as long as the standard at the higher wavelength and the unknowns at the lower wavelength are in the linear region of the detector as you state that you are.

Any variation in the linearity will cause a variation in relative response. I would recommend that you at least bracket your samples with a relative response check.

[Furry_dice]

For the original question it is not a surprise at all. One is a PDA the other is a Dual wavelength detector. They use a completely different method of detection of the UV signal so the response is almost bound to be different. For the details on the differences the manuals are actually a reasonable place to start.


Added to this would be the different ages of the UV lamps, the sensitivity of the different light detectors and then the different settings (band width etc)....in fact if the two did agree that would be remarkable.

[HW Mueller]

How does absorbance depend on lamp age or light detector sensitivity? I only know that the specific absorbance in the B.-L. law depends on wavelength, thus on bandwidth, and on Io/I (the intensity ratio, not the intensity of the light).