why is retention and peak width measured in time? is there a better theoretical parameter?
Since the chromatogram reads in amout on the vertical axis and time on the horizontal axis, how else would you measure it?
well, the manual says we have to plot area and also to plot peak height. but i was also looking into plotting it as chart distance but not quite sure how that works
Retention and peak width are measured in time because they represent temporal characteristics of a chromatographic separation. In chromatography, compounds are separated based on their unique interactions with the stationary phase and the mobile phase.
Retention time refers to the time it takes for a compound to elute or come out of the chromatographic column. It is a measure of how strongly a compound interacts with the stationary phase. Compounds that interact more strongly will have longer retention times, while those with weaker interactions will have shorter retention times.
On the other hand, peak width corresponds to the width or broadness of a peak on the chromatogram. It is a measure of the separation efficiency or resolution of the chromatographic system. Smaller peak widths indicate better separation and higher resolution, while broader peaks indicate poorer separation and lower resolution.
While time-based measurements are widely used and provide useful information about separation characteristics, there are other theoretical parameters that can be employed as well. One alternative parameter is plate count or theoretical plates. Plate count represents the number of hypothetical equilibrium stages that a compound undergoes during its migration through the column. It can be calculated using the Van Deemter equation, which considers contributions from different processes that affect peak broadening, including longitudinal diffusion, eddy diffusion, and mass transfer.
Plate count provides a quantitative measure of resolution and can be used to compare the efficiency of different chromatographic systems. However, time-based measurements like retention time and peak width are more commonly used because they are simple, easily measurable, and provide a straightforward interpretation in real-world applications. They are also convenient for method development, optimization, and quality control purposes.
In summary, while there are alternative theoretical parameters like plate count, retention time and peak width measured in time are commonly used in chromatography due to their simplicity, practicality, and ability to provide valuable information about separation characteristics.