Chromatography Forum

Hi,

I'm new to using Chemstation, and have created a calibration curve for AAA using known standards. In the calibration table, I've identified all the peaks as well as their RT and amounts. However, when the unknowns are run, Chemstation doesn't calculate three of my peaks- namely ASN, GLN, and TRP. The retention times are virtually identical to my standards; does anyone know how I can get Chemstation to calculate the amount and area? I'm able to get all the other AA present in the sample, it's just those three I'm having trouble with- they show up as --- in the report (they are in the chromatogram though!)

Thanks!

What is the lowest concentration of the standard peaks? If you run the lowest standard as an unknown after doing the calibration, are all of the peaks reported? Are the three peaks not reported in your unknowns below some sort of threshold limit (peak height, area, concentration)?

You report that the retention times of the three unknowns are virtually identical to the standards but are they within the retention time windows that you have set?

The lowest concentration of my standards is 100pmol/ul. when running a standard as an unknown, the peaks do come out and are reported. Based on the height and relative size of my unknown's peaks (after overlaying the chromatograms) the unknown should be within my standard curves.

Through trial and error with Chemstation, I was able to get the program to report the amounts and areas of the three aa I was missing.

Thanks for your help!

UR USING ISTD OR ESTD MODE