Glossary of HPLC Terms

Asymmetry (As)—Factor describing the shape of a chromatographic peak (Eq. 2.17). 

Band Broadening—The process of increasing peak width and dilution of the solute as it travels through the column. 

Column—A tube that contains packed solid material containing the stationary phase. Typical HPLC columns are stainless steel tubes packed with silica-based bonded phases. 

Efficiency or Plate Number (N)—A measure of column performance. N is calculated from retention times and peak widths (Eq. 2.10 and 2.11). 

Mobile Phase—A solvent that carries the sample through the column. Typical mobile phases in RPLC are mixtures of water with acetonitrile or methanol. 

FIGURE 23 HPLC chromatogram illustrating the calculation of LOQ at a signal-to-noise ratio of 10. Note that the peak-to-peak noise is often overestimated by the analyst as shown. 

Retention— the tendency of a solute to partitioned into the stationary phase of the column. 

Resolution (RJ— the degree of separation between two peaks as defined by the difference in their retention time divided by the average peak width. 

Adsorption Chromatography—Separation mode resulting from compounds that have different adhesion rates for the packing surface. (See Normal-Phase Chromatography.) 

Alpha (a)—(Separation or chemistry factor). A measure of separation between two peak maxima. Ratio of their k values. 

Attenuation—Measure of detector sensitivity. A larger value means less sensitivity. 

Autoinjector—An injection device for automated methods development in which the sample loop is repeatedly filled from a large sample reservoir rather than a sample vial carousel. 

Autosampler—A multiple sample injector, usually with a rack or carousel to hold sample vials or a sample well plate, designed for unattended programmed operation in which a sample is loaded by either pushing or pulling sample into the loop injection loop with air or hydraulic pressure. 

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The fourth item is a glossary of HPLC terms. I have tried to include much of the terminology and buzzwords used in the field. 

This chapter provides an overview of basic terminology and essential concepts in HPLC including retention, selectivity, efficiency, resolution, and peak symmetry as well as their relationships with key column and mobile phase parameters. The resolution and van Deemter equations are discussed. The concepts of peak capacity and method orthogonality as well as key gradient parameters such as gradient time and flow rate are described. An abbreviated glossary of HPLC terms is listed. 

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