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The optimization of a porous structure to ensure good separation performances is always a significant issue in high-performance liquid chromatography column design. Recently we reported the homogeneous embedment of Ag nanoparticles in periodic mesoporous silica monolith and the application of such Ag nanoparticles embedded silica monolith for the high-performance liquid chromatography separation of polyaromatic hydrocarbons. However, the separation performance remains to be improved and the retention mechanism as compared with the Ag ion high-performance liquid chromatography technique still needs to be clarified. In this research, Ag nanoparticles were introduced into a macro/mesoporous silica monolith with optimized pore parameters for high-performance liquid chromatography separations. Baseline separation of benzene, naphthalene, anthracene, and pyrene was achieved with the theoretical plate number for analyte naphthalene as 36 000 m−1. Its separation function was further extended to cis/trans isomers of aromatic compounds where cis/trans stilbenes were chosen as a benchmark. Good separation of cis/trans-stilbene with separation factor as 7 and theoretical plate number as 76 000 m−1 for cis-stilbene was obtained. The trans isomer, however, is retained more strongly, which contradicts the long- established retention rule of Ag ion chromatography. Such behavior of Ag nanoparticles embedded in a silica column can be attributed to the differences in the molecular geometric configuration of cis/trans stilbenes. [ABSTRACT FROM AUTHOR]

Fifteen title compounds with four fused rings and two varying substituents were used to further specify the scope and limitation of a theoretical approach (the Snyder theory and LSChrom software) for selection of mobile phases avoiding any trial and error experiments. Based on the structure of the compounds, the theoretical treatment predicted values of strength ε of suitable mobile phases for TLC, namely 0.311 for silica and 0.446 for alumina. Sixteen specific mobile phases with such or close values of ε were arbitrarily selected from lists prepared by complex calculations. They were used to perform TLC. The data obtained showed that the retentions in all 256 measurements done were above the origin and below the solvent front. Thus, a good agreement between the theoretical and experimental data was established, thus proving a successful application of the approach. The retentions of all compounds and separation of one cis/trans pair depended on the stationary phase, ε, and the tuning parameters m and P' of the mobile phases. [ABSTRACT FROM AUTHOR]

Avoiding any trial and error experiments, the LSChrom software incorporating the Snyder theory was applied successfully to automatic selection of mobile phases for thin‐layer chromatography (TLC) of substituted isochromanones 1–8 and the spiro analogues 9–12. The procedure takes into account the adsorption properties of the mobile phase (parameter ε and tuning parameters m and P ′), stationary phase and sample structure expressed by relevant groups. The calculations yielded a recommended value of ε and subsequently a list of mobile phases having this value of ε. The approach was applied to TLC on two types of silica and, for the first time, on alumina. Within about 130 measurements using 10 computer selected mobile phases, the retention of any compound fell in a favorable range (0 F [ABSTRACT FROM AUTHOR]