ICS-1000 Ion Chromatography System Operator's Manual

ICS-1000 Ion Chromatography SystemCell Constant (k)A factor determined experimentally by measuring the conductance (G) of astandard solution of known equivalent conductivity (k).k=κ ⁄ GThe value of k depends upon the surface area of, and distance between, theelectrode faces in the conductivity detector cell.k=l ⁄ AWhere: l = lengthA = area of one electrode (the other electrode is equal tothe first)ChannelingThe preferential flow of liquid along more open, less resistant paths through thecolumn packing. This causes Band Spreading.Column Efficiency (N)A measure of the narrowness of analyte bands as they elute from the column.High efficiency is desirable because resolution between closely spaced bandsimproves with greater efficiency. For a symmetrical (Gaussian) peak, columnefficiency can be determined by the following:N = 5.54(t 1 /W 1/2 ) 2Where: t 1 = the peak retention time (in seconds)W 1/2 = the peak width at 1/2 height (in seconds)Column efficiency is proportional to column length: for a given resin and columndiameter, increasing the column length increases the column efficiency.Synonymous with Theoretical Plates.Column Selectivity (a)Describes the relative separation of the band maxima between two adjacent peaks.Selectivity can be determined by the following:a = (t 2 - t 0 )/(t 1 -t 0 )Where: t 1 and t 2 = retention time of components 1 and 2, respectivelyt 0 = retention time of unretained components (void volume)Concentrator ColumnA short column used to retain and concentrate analytes from a measured volumeF-2 Doc. 031879-01 3/03