The contribution to A term (column packing regularity) is significantly reduced too (−40%), because of a rougher surface of core-shell particles. The porous shell provides less band broadening by reducing the dispersion of the solute molecules within a packed bed owing to a lower pore volume available for longitudinal diffusion (B term in the van Deemter equation decreased up to 30%) and a shorter diffusion path length, which diminishes the contribution of the C term to band broadening due to the fast mass transfer. This combination of materials provides columns with speed and efficiency similar to columns packed with sub-2 μm totally porous particles, while maintaining low back pressure thus can be used on conventional HPLC instrument, with a maximum pressure of 300 bar. The modern sub-3 μm core-shell particles have a 1.7 μm solid core wrapped in a porous layer or shell of a 0.5 μm silica adsorbent, with a final particle size of 2.6 μm. As a main drawback, the cost of an UHPLC apparatus is still prohibitive for an average laboratory, or it is difficult to switch from known procedures. By the application of this instrumentation, separations 5- to 10-fold faster than a conventional LC system can be achieved, with an important solvent saving. Sub-2 μm particles columns require a dedicated instrumentation that can work at very high pressure (up to 1200–1300 bar), and therefore this technique has been called ultrahigh-performance liquid chromatography (UHPLC). The traditional packed columns still dominate the market, but in the last decade columns packed with sub-2 μm particles, columns packed with fully porous particles, and short columns packed with nonporous or core-shell (superficially porous) particles are gaining popularity. In fact, in order to maximize HPLC performances in separation efficiency and speed, the size of the particles packed into the columns has been considerably decreased. HPLC has evolved dramatically in the recent years, especially due to the development of new column technologies. High-performance liquid chromatography (HPLC) is an essential analytical technique for qualitative and quantitative determinations in many fields, for research, diagnostic, and manufacturing purposes. The literature hereby described shows how the outstanding performances provided by core-shell particles column on a traditional HPLC instruments are comparable to those obtained with a costly UHPLC instrumentation, making this novel column a promising key tool in food analysis. Their use has proved to be particularly advantageous for the determination of compounds at trace levels or when a large amount of samples must be analyzed fast using reliable and solvent-saving apparatus. The present paper presents their most recent applications in food analysis. The increased separation efficiency provided by the new technology of column packed with core-shell particles in high-performance liquid chromatography (HPLC) has resulted in their widespread diffusion in several analytical fields: from pharmaceutical, biological, environmental, and toxicological.
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