Chromatography Forum

dear friends...

I have run various samples on this HPLC attached to a PDA, but this is the first time I see this:

compounds like methanol and ethanol are getting only 50-120 mAU. I have noticed most compounds get values higher than 2000 mAU. They are all standards, about 2000 mg/L.

What does this mean?

Were they poorly identified? Does this suggest a GC would analyse them better?

Method:
Mobile phase: 0.7 ml/min for 10 min.
acetonitrile 70% / water 30%.

Thanks

What wavelength are you looking at? Look up the UV spectrum of an alcohol (ethanol or methanol, for example) and you will have your answer.

I know that detector technology has improved somewhat but I would still prefer to see peaks of no more than 1000 mAU.

I've seen methods with peaks at 2 -3000 mAU where calibrations are non-linear (detector overload), but with reduced injection volumes and lower Absorbances are perfectly linear.