Would some one tell me how to determine if the UV detector of a HPLC system is saturated. I developed a HPLC method. The method has a r2 of 0.999 at the range of 0.05 to 0.3mg/ml. The peak shape of analyte is sharpe. Intensity of the peak is about 0.3 AU (Instrument up limit is 2.0 AU). Therefore, I belive the method is fine and the detector is not saturated. However, my boss told me that the HPLC UV detector is saturated. Because the peak area reads > 100,000. He belives the right peak area for this instrument is <50,000 (Waters Mellinnum). To prove the detector is not saturated he asks me to determine the linearity of the same standand solutions with a UV specphotometer. As you will guess, the UV specphotometer is much sensitive. The hihger levels of the standard solutions were out of detection range (sautrated). Does this means the same standard solutions is saturated on HPLC UV detector? Please help me if I am wrong. Thank you in advance.

Maximum concentration of standard solution in HPLC detector is lower than in UV spectrophotometer, because of dilution the sample in eluent and distribution of concentration within the peak width. For more width peaks, maximum concentration is lower.
Testing by UV spectrometer is not proper, if path lengths in spectrometer and in HPLC are different or different sensitivity of detectors.
Practically you can prepare a plot of detector response against the standard concentration. It should be linear up to detector saturation, where it start nonlinearly or reach plateau. If two times higher concentration than your maximum concentration is still in linearity range, then is no danger.

Why don't you plot your chromatogram full scale?
If there is no saturation, the peak top will be as sharp as at lower concentrations (you may zoom on it). If saturation occurs, the peak top will have a characteristic flat appearance. I hope your boss will be satisfied.
I agree also with the previous posting (more rigorous approach!)

Does you boss have pointy hair, like Dilbert's boss ?

An easy way to demonstrate linearity of your curve and therefore show that the detector is or is not saturated is to plot area/concentration (y-axis) versus log(concentration) (x-axis). Draw three control lines, the average area/concentration (Rc) , 0.95Rc, and 1.05Rc. If all the data points fall inside the 0.95Rc and 1.05Rc control bars, you have good evidence of linearity, and non-saturation of the detector.

Peak area can't be used to determine saturation under any but the most controlled conditions--such as at a given retention time. If you've run multiple compounds with similar responses at the same concentrations, you'll see that the peaks have similar areas, but latter peaks are shorter and wider.

If you are trying to push system capacity to the maximum, use longer retention times (wider peaks) and you can pack more material into the system and stay within the linear range.

While not much of a problem in HPLC, this is a common problem in GC using a number of detectors, but especially electron capture detectors.