Protein binding study of catechin hydrate and genistein by high-performance frontal analysis

High-performance frontal analysis (HPFA) was used for the protein binding study of catechin hydrate and genistein to human serum albumin (HSA). The experiment was performed on a Develosil 100Diol-5 column, and sodium phosphate buffer (pH 7.4 and ionic strength of 0.17) was used as the mobile phase. The mixtures of the drug-HSA solution were directly injected into the HPFA column, the HSA was eluted first and the unbound drugs were eluted out as a trapezoidal peak with a plateau region. The unbound drug concentration was determined from a plateau height of the plateau region and the experimental data were fitted by Scatchard equation. The binding constants (K) and binding affinities (nK) of the drug to HAS were K=1.32×10⁴ (L mol⁻¹), nK=0.47×10⁴ (L mol⁻¹) for catechin hydrate, and K=5.17×10⁴ (L mol⁻¹), nK=2.14×10⁴ (L mol⁻¹) for genistein.     

Separation of perillyl alcohol from the peel of citrus unshiu by supercritical CO2 and preparative high-performance liquid chromatography

To separate perillyl alcohol (POH), a potential anti-cancer agent, the peel of citrus unshiu was extracted by supercritical CO₂ extraction (SCE) system at 50 ‡C, 200 bar and 6 kg CO₂/hr/kg sample. The extracts were partitioned by acetonitrile/hexane (90/10, vol%). POH was eluted in the acetonitrile phase. An open-tubular chromatography with silica gel (40–63 Μm) was used to purify POH from the acetonitrile phase. Mobile phase was hexane/ethyl acetate (90/10, vol%). To obtain POH in a pure form, finally preparative high-performance liquid chromatography was applied. The collection of POH from citrus unshiu peel was achieved on a laboratory-prepared Chromatographic column (300x3.9 mm) packed with 15 Μm C₁₈ preparative packings. The composition of mobile phase was water/acetonitrile (50/50, vol%). The flow rate of the mobile phase was 1 ml/min and UV wavelength was fixed at 205 nm. It was found that the total yield of POH was 1.6xl0^-3 (wt%) as the dry powder of citrus unshiu peel.     

Separation of perillyl alcohol from Korean orange peel by solvent extraction and chromatography

Perillyl alcohol, abundant mainly in oranges, has chemotherapeutic activity against carcinogenesis. The peel of Korean oranges was extracted by methanol, and the extract was partitioned by methanol-extract/water/chloroform, (20/5/30 vol%). To concentrate perillyl alcohol of the water-phase in the previous partition step, a glass column (2.5 i.d. x 15 cm) with reversed-phase C₁₈ packings (40–63 μm) was used. Finally, to obtain perillyl alcohol in a pure form, reversed-phase high-performance liquid chromatography (RP-HPLC) was applied. Mobile phases used were water, methanol, and acetonitrile. The flow rate of the mobile phase was 1 ml/min and UV wavelength was fixed at 205 nm. The resolution of perillyl alcohol from Korean orange peel was achieved on a μ-Bondapak C₁₈ column (3.9x300 mm, 10 μm) and in-house Chromatographic column packed with 15 μm C₁₈ preparative packings. From the experimental results, the mobile phase composition was water/acetonitrile, (65/35 vol%) and the retention time of perillyl alcohol was 20.5 min in the analytical μ-Bondapak column. The effect of injection volumes was investigated in the preparative column.     

Nonlinear isotherm of benzene and its derivatives by frontal analysis

Adsorption behavior of a solute is one of the most important factors to consider when designing a batch and a continuous liquid chromatographic separation process. In liquid chromatography, this behavior is based on the adsorption equilibrium between the liquid mobile-phase and solid stationary-phase. However, most retention models have been developed under a linear adsorption isotherm: very few researchers have investigated the relationship between the adsorption parameters and the mobile phase composition, and some empirical models have been introduced. In this work, adsorption isotherms were obtained by a frontal analysis for three small molecular compounds (benzene, toluene, and chlorobenzene) on a commercial C₁₈ bonded silica column. The absorption based on the Langmuir, Freundlich, and Langmuir-Freundlich models were investigated according to changes of the composition of methanol highly enriched eluent. The calculations and analysis of the coefficients obtained for the three models confirm that the adsorption data for solutes are best modeled with the Langmuir-Freundlich isotherm. In spite of the acceptable accuracy, Langmuir and Freundlich isotherm models couldn’t satisfactorily describe the mechanism and provide objective information on the physical nature of the absorption.     

低碳醇改性无氟泡沫的性能分析与扑灭油池火的实验研究

针对现有氟碳类泡沫灭火剂关键组分PFOS因国际环境公约出于环保和健康而限用,以及现有泡沫灭火剂还存在析液速度快而影响灭火能效等问题,在前人及团队探究无氟泡沫复配方案基础上,基于火灾化学理论与表面活性剂技术,遴选碳氢/有机硅表面活性剂(LS-99/SDS)为基剂,通过引入可改善气泡聚并的低碳醇(乙醇、正丙醇和异丁醇)调控泡沫的发泡倍数和25%析液时间等性能,开展含醇泡沫和无醇泡沫的灭火对比实验,考察低碳醇引入后的泡沫灭火能效。结果表明,引入适量浓度低碳醇可显著影响LS-99/SDS复配体系的发泡倍数和25%析液时间。相比乙醇和正丙醇,当异丁醇质量分数为0.1%时,可有效延缓含醇泡沫的析液进程和降低析液速率。通过灭火过程的火焰温度测定,发现含醇泡沫作用下10 cm和20 cm高度处的火焰最大降温速率为20.1℃·s^-1和11.2℃·s^-1,相较于无醇泡沫体系降温效果显著,降温增幅分别为39.58%和14.29%。含醇泡沫灭火剂相对于无醇泡沫灭火时间缩短了3.6 s,缩短幅度为37.5%。适量浓度的异丁醇引入到无氟泡沫体系中,可有效延缓泡沫析液进程,提高泡沫体系的发泡倍数及稳泡性能,为无氟泡沫的优化设计提供了一条新路径。建立了基于25%析液时间、平均析液速度、最大降温速率和灭火时间等综合指标的灭火效果考察方法,为泡沫灭火效能的实验室评价提供了参考依据。     

低碳醇改性无氟泡沫的性能分析与扑灭油池火的实验研究

针对现有氟碳类泡沫灭火剂关键组分PFOS因国际环境公约出于环保和健康而限用,以及现有泡沫灭火剂还存在析液速度快而影响灭火能效等问题,在前人及团队探究无氟泡沫复配方案基础上,基于火灾化学理论与表面活性剂技术,遴选碳氢/有机硅表面活性剂(LS-99/SDS)为基剂,通过引入可改善气泡聚并的低碳醇(乙醇、正丙醇和异丁醇)调控泡沫的发泡倍数和25%析液时间等性能,开展含醇泡沫和无醇泡沫的灭火对比实验,考察低碳醇引入后的泡沫灭火能效。结果表明,引入适量浓度低碳醇可显著影响LS-99/SDS复配体系的发泡倍数和25%析液时间。相比乙醇和正丙醇,当异丁醇质量分数为0.1%时,可有效延缓含醇泡沫的析液进程和降低析液速率。通过灭火过程的火焰温度测定,发现含醇泡沫作用下10 cm和20 cm高度处的火焰最大降温速率为20.1℃·s^-1和11.2℃·s^-1,相较于无醇泡沫体系降温效果显著,降温增幅分别为39.58%和14.29%。含醇泡沫灭火剂相对于无醇泡沫灭火时间缩短了3.6 s,缩短幅度为37.5%。适量浓度的异丁醇引入到无氟泡沫体系中,可有效延缓泡沫析液进程,提高泡沫体系的发泡倍数及稳泡性能,为无氟泡沫的优化设计提供了一条新路径。建立了基于25%析液时间、平均析液速度、最大降温速率和灭火时间等综合指标的灭火效果考察方法,为泡沫灭火效能的实验室评价提供了参考依据。