alumina - an adsorbent sometimes used in adsorption chromatography. Aluminum oxide (Al2O3) is a porous adsorbent that is available with a slightly basic surface. For this reason, it can have advantages over silica, which is considered to have an acidic surface.
analyte - the chemical species being investigated by an analytical method. Usually the identification and/or the amount is to be determined by a separation and estimation technique.
anion-exchange chromatography - the ion-exchange procedure used for the separation of anions. Both resins and bonded phases are available for this mode. The tetralkylammonium group is a typical strong anion-exchange functional group. An amino group bonded on the rigid adsorbent surface would be the example of a weak anion exchanger (WAX).
asymmetry - factor describing the shape of a chromatographic peak. Theory assumes a Gaussian shape and that peaks are symmetrical. The peak asymmetry factor is the ratio (at 10% of the peak height) of the distance between the peak apex and the back side of the chromatographic curve to the distance between the peak apex and the front side of the chromatographic curve. A value > 1 is a tailing peak, while a value <1 is a fronting peak.