HPLC Products

Normal

Problem

Note here that the bottom of the peaks crosses the baseline with sharp corners, not normal gaussian peaks. This is because the peaks start much lower down and what is displayed is only the top part of the peak.

How can this happen? Most modern data systems are bipolar (ie they operate to +/-1V or +/-1AUFS, and not just from 0-1V. However if the data system is accidentally set to work only from zero, any time the real baseline goes below zero, the system will continue to draw a totally flat baseline at zero (ie no noise) and the only time that peaks will be displayed is if they are large enough to show above the artifical baseline at zero! Hence what is observed is triangular peaks rather than gaussian peaks, and of course any peak areas measured will be very much understating the true area of the peak.

The solution? Go into the data system configuration file and set the detector channel to be BIPOLAR.