Recent HPLC strategies to improve sensitivity and selectivity for the analysis of complex matrices

Recently, various approaches have been addressed to improve chromatographic performance in terms of sensitivity or selectivity, from the development of novel on-line (or off-line) enrichment methodologies, to the improvement of stationary-phase type and multidimensional chromatography, to novel and more performing detectors such as tandem mass spectrometry (MS/MS), nuclear magnetic resonance (NMR), and infrared spectrometry (IR). For the analysis of complex matrices (e.g., biological fluids, plant extracts, food, and environmental samples), coupling chromatographic instrumentation with these detectors provides a powerful analytical device that can be applied in many fields, such as analysis of pharmaceutical and natural products (and medicinal plant), quality control, and environmental trace analysis. This review describes major advances in the HPLC field in terms of enrichment techniques and chromatographic separation, and especially in terms of detector improvement for a complete identification and quantification of targeted analytes. The possibility of high-throughputs analyses, as a consequence of sensitivity and selectivity enhancement in drug and metabolites profile and multi-residue assays for natural compounds and/or products containing natural species, is also highlighted. Finally, it is shown how multivariate analysis may enhance analytical performance in terms of useful analytical information that can be extracted from experimental data and in terms of methods for exploring and modeling data. Chemometrics provides tools for making the most of analytical signals, once selectivity and sensitivity have been improved from the chemical point of view.