The Chromeleon software automatically calculates the best data collection rate and filter constant, based on the value you enter for the peak width in the Instrument Method Wizard.

If you want to select a different data collection rate and filter constant, note the guidelines below.

Data Collection Rate

The data collection rate is the number of data points per second (Hz) that the Chromeleon software collects from the detector and stores as raw data.

When you select a data collection rate, observe the following guidelines:

  • In general, each peak should be defined by at least 20 data points. For chromatograms with co-eluting peaks or low signal-to-noise ratios, 40 data points per peak are recommended.

  • If the data collection rate is too low, the start points, maxima, and end points of peaks will not be determined accurately.

  • If the data collection rate is too high, data files may need more disk space and post-run analyses may require more processing time.

  • If all peaks are relatively wide, select a lower data collection rate (for example, 1.0 Hz). This saves disk space and allows for a faster display of data in the Chromeleon software.

  • If any peaks of interest are less than a few seconds, select a higher data collection rate (10.0 Hz, for example).

  • Consider also the filter constant when setting the data collection rate. Set the two parameters together in order to optimize the amount of data points collected, and reduce short-term noise, while still maintaining peak height, symmetry, and resolution. See below.

Filter Constant

The filter constant is applied to the output current to electronically reduce the baseline noise during the analysis.

When setting a filter constant, observe the following:

  • A small filter constant, such as 0.2 seconds, removes little baseline noise.

  • A large filter constant, such as 10.0 seconds, smoothes the baseline significantly.