A B S T R A C TSample preparation is a crucial bottleneck in the whole analytical process. Solid-phase sorbents (SPSs) have aroused increasing interest in research on sample preparation, as they have key roles in obtaining high clean-up and enrichment efficiency in the analysis of trace targets present in complex matrices. The objective of this review is to provide a broad overview of the recent advances and applications of SPSs in sample preparation prior to chromatographic analysis, during the period 2008-13. We include SPSs, such as molecularly-imprinted polymers, carbon nanomaterials, metallic nanoparticles and metal organic frameworks, focusing on solid-phase extraction, solid-phase microextraction, matrix solid-phase dispersion and stir-bar sorptive extraction of typical pollutants in environmental, biological, food and pharmaceutical samples. We propose remaining challenges and future perspectives to improve development of new SPSs and to apply them further.

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Recent advances in enrichment techniques for trace analysis in capillary electrophoresisCE is gaining great popularity as a well-established separation technique for many fields such as pharmaceutical research, clinical application, environmental monitoring, and food analysis, owing to its high resolving power, rapidity, and small amount of samples and reagents required. However, the sensitivity in CE analysis is still considered as being inferior to that in HPLC analysis. Diverse enrichment methods and techniques have been increasingly developed for overcoming this issue. In this review, we summarize the recent advances in enrichment techniques containing off-line preconcentration (sample preparation) and on-line concentration (sample stacking) to enhancing sensitivity in CE for trace analysis over the last 5 years. Some relatively new cleanup and preconcentration methods involving the use of dispersive liquid-liquid microextraction, supercritical fluid extraction, matrix solid-phase dispersion, etc., and the continued use and improvement of conventional SPE, have been comprehensively reviewed and proved effective preconcentration alternatives for liquid, semisolid, and solid samples. As for CE on-line stacking, we give an overview of field amplication, sweeping, pH regulation, and transient isotachophoresis, and the coupling of multiple modes. Moreover, some limitations and comparisons related to such methods/techniques are also discussed. Finally, the combined use of various enrichment techniques and some significant attempts are proposed to further promote analytical merits in CE.