Linearity issues

[raman_srividya]

We are currently analyzing phenol in UPLC system at 240 nm. Linearity of phenol (0.1 mg/mL -0.7mg/ml)is achieved in UV detector using in dual wavelength mode but the same cannot be achieved with PDA detector . Any thoughts

[Poly Styrene]

You need to provide _full_ details of your analysis. Are the measurements carried out on on the same HPLC instrument with two detectors, or is it completely separate systems? And why measure at 240 nm? What is the mobile phase/matrix? λmax for phenol should be ~270 nm, did you determine it experimentally for your solvent system/samples?

[Peter Apps]

We are currently analyzing phenol in UPLC system at 240 nm. Linearity of phenol (0.1 mg/mL -0.7mg/ml)is achieved in UV detector using in dual wavelength mode but the same cannot be achieved with PDA detector . Any thoughts

Details, details, details. We can't help without the details. How may levels of standards, how many replicates at each level, and how many times have you repeated the calibration ? Also the details of the analysis. The ore you don't tell us the more we can't help you. Why are you calibrating over such a narrow range ?.

Peter