Chapter 6 - Characterization of analytes and matrices

Abstract

The chemical nature of the sample, mainly of its analytes but also of the matrix of the sample, is the main factor to consider in the selection of the HPLC type, and within a type of a specific HPLC method. For this reason, it is important to understand the characteristics of the analytes and of the matrix that influence the HPLC separation and detection. Depending on the number of atoms in a molecule, the solutes/analytes are initially divided into small molecules and macromolecules. Small molecules are further classified based on their chemical structure. First, the organic and inorganic compounds are separately classified. Organic compounds are usually considered as those that contain in their molecule carbon and usually hydrogen. A small number of compounds that are considered organic do not contain hydrogen. Also, there are a few classes of compounds that contain carbon and are not considered organic (such as metal carbonates, carbides, and the oxides of carbon). Metalorganic compounds such as complexes of organic compounds with metals are usually considered organic. More complex compounds are also known. The classification in organic or inorganic compounds does not differentiate small molecules from large molecules (polymers). Many polymers such as polymeric carbohydrates, proteins, nucleic acids, and a wide variety of synthetic polymers are organic compounds. Polymers that contain inorganic and organic components such as silicones are also known. Samples in HPLC analysis may contain a variety of components with a variety of structures.