An Overview of Solid Phase Extraction as a Separation and Concentration Method

Qualitative or quantitative determination of certain analytes present at low concentrations in food,environmental, and biological samples is of importance for the environment and public health. Todetermine the selected analyte at sufficiently low concentrations using conventional techniquessuch as gas or liquid chromatography, certain pre-separation and concentration techniques arerequired. Sample preparation before instrumental analysis is one of the most important and criticalsteps. The main objectives of sample preparation methods are (1) separation of the analyte fromthe matrix medium and/or (2) enrichment of the analyte at low concentrations. One of the methodsfrequently used in analytical applications for this purpose is the solid-phase extraction (SPE)method. SPE is a well-known sample preparation technique, which allows for isolation of theanalytes from the sample or removal of the interferents from the matrix without using hugeamounts of organic solvents. One of the major advantages of SPE technique is the availability ofwide range of different materials. In addition to commercially available sorbents such as silicabased sorbents (modified with C8, C18, -phenyl, -NH2 and –CN groups), carbon-based sorbents(graphitized carbon black, porous graphitic carbon) and porous polymeric sorbents, which arecommonly used in the SPE method, numerous studies have been reported in recent years on thesynthesis of micro or nano-sized sorbents with superior properties (selectivity, affinity andincreased surface area, removal of sorbent by application of magnetic field, etc.) and their use asSPE materials, in parallel with developments in materials science1. The common aim of thesestudies is to achieve better reproducibility and selectivity in analyte determination, to reach lowerdetection limits, and to reduce costs by reusing the sorbent without losing its effectiveness2. Manypollutants that threaten the environment and human health (endocrine disruptors, antibiotics, etc.)can be successfully determined by chromatographic techniques by enriching them in the samplepreparation step with SPE procedures applied with new generation sorbents. Because, there is stilla huge interest in searching for new materials characterized by high selectivity and capacity,which could provide an alternative to typical ones used in SPE. The basic principles of SPE aswell as current and possible future applications in Analytical Chemistry will be presented andbriefly discussed during the lecture.