High Performance Liquid Chromatography as a Cleanup Technique

Abstract

High performance liquid chromatography (HPLC) is widely used in the analysis of environmental samples as a means of identification and quantititation of chemicals. However, there are occasions where it can be employed as a cleanup or purification step prior to further determination by some other technique. This chapter will concentrate on those HPLC techniques that are primarily employed as cleanup techniques to reject extraneous material so that the compound of interest can be measured by a further mode of detection. In this regard the technique serves much the same function that the classical steps of solvent partition, column and thin layer chromatography have served to residue chemists over the years. Most often HPLC is used as sample cleanup for those samples that contain high levels (concentrations) of interfering substances of no interest (lipids, sugars, proteins, salts, and so on) and low levels of the chemicals of interest that must be first separated from each other prior to actual analyte determination. Other occasions where the use of HPLC cleanup occurs is in the analysis of samples containing low levels of analytes in which the HPLC mode of detection is inferior to some other detection mode [e.g., ultraviolet (UV) absorption detection is generally less sensitive than either mass spectrometry (MS) or electron capture (EC) detection].