Liquid-solid Chromatography Research Articles

Liquid–Liquid Chromatography: Current Design Approaches and Future Pathways

Since its first appearance in the 1960s, solid support-free liquid-liquid chromatography has played an ever-growing role in the field of natural products research. The use of the two phases of a liquid biphasic system, the mobile and stationary phases, renders the technique highly versatile and adaptable to a wide spectrum of target molecules, from hydrophobic to highly polar small molecules to proteins. Generally considered a niche technique used only for small-scale preparative separations, liquid-liquid chromatography currently lags far behind conventional liquid-solid chromatography and liquid-liquid extraction in process modeling and industrial acceptance. This review aims to expose a broader audience to this high-potential separation technique by presenting the wide variety of available operating modes and solvent systems as well as structured, model-based design approaches. Topics currently offering opportunities for further investigation are also addressed.

Importance of Downstream Processing of Natural Astaxanthin for Pharmaceutical Application

Astaxanthin (ASX) is a xanthophyll pigment considered as a nutraceutical with high antioxidant activity. Several clinical trials have shown the multiple health benefits of this molecule; therefore, it has various pharmaceutical industry applications. Commercial astaxanthin can be produced by chemical synthesis or through biosynthesis within different microorganisms. The molecule produced by the microorganisms is highly preferred due to its zero toxicity and superior therapeutic properties. However, the biotechnological production of the xanthophyll is not competitive against the chemical synthesis, since the downstream process may represent 70–80% of the process production cost. These operations denote then an opportunity to optimize the process and make this alternative more competitive. Since ASX is produced intracellularly by the microorganisms, high investment and high operational costs, like centrifugation and bead milling or high-pressure homogenization, are mainly used. In cell recovery, flocculation and flotation may represent low energy demanding techniques, whereas, after cell disruption, an efficient extraction technique is necessary to extract the highest percentage of ASX produced by the cell. Solvent extraction is the traditional method, but large-scale ASX production has adopted supercritical CO2 (SC-CO2), an efficient and environmentally friendly technology. On the other hand, assisted technologies are extensively reported since the cell disruption, and ASX extraction can be carried out in a single step. Because a high-purity product is required in pharmaceuticals and nutraceutical applications, the use of chromatography is necessary for the downstream process. Traditionally liquid-solid chromatography techniques are applied; however, the recent emergence of liquid-liquid chromatography like high-speed countercurrent chromatography (HSCCC) coupled with liquid-solid chromatography allows high productivity and purity up to 99% of ASX. Additionally, the use of SC-CO2, coupled with two-dimensional chromatography, is very promising. Finally, the purified ASX needs to be formulated to ensure its stability and bioavailability; thus, encapsulation is widely employed. In this review, we focus on the processes of cell recovery, cell disruption, drying, extraction, purification, and formulation of ASX mainly produced in Haematococcus pluvialis, Phaffia rhodozyma, and Paracoccus carotinifaciens. We discuss the current technologies that are being developed to make downstream operations more efficient and competitive in the biotechnological production process of this carotenoid.

Inverse liquid-solid chromatography to evaluate drug interactions with organosilane-modified polydimethylsiloxane for use in body-on-a-chip systems.

Body-on-a-chip and organ-on-a-chip systems utilize polydimethylsiloxane (PDMS) because of the relative suitability of the material for fabrication of microfluidic channels and chambers used in these devices. However, hydrophobic molecules, especially therapeutic compounds, tend to adsorb to PDMS, which may distort the dose-response curves that feed into the pharmacokinetic/pharmacodynamic models used to translate preclinical data into predictions of clinical outcomes. Surface modification by organosilanes is one method being explored to modify PDMS, but the effect of organosilanes on drug adsorption isotherms is not well characterized. We utilized Inverse Liquid-Solid Chromatography to characterize the adsorption parameters of the drugs acetaminophen, diclofenac, and verapamil with native PDMS and organosilane-modified (fluoropolymer (13F) and polyethylene glycol) PDMS surfaces, to correlate the modifications with changes in drug adsorption. It was determined that the organosilane modifications significantly changed the energy of adsorption of the test drug utilizing our methodology.

Научная и организационная деятельность лаборатории хроматографии Института физической химии с момента её образования

В 2020 г. лаборатория хроматографии и хромато-масс-спектрометрии в ИФХЭ РАН отмечает 70-летие со дня её основания. В статье рассказывается об организации лаборатории хроматографии в СССР, её становлении и перспективах развития. Приведены данные о наиболее важных результатах научной и организационной деятельности заведующих и сотрудников лаборатории на протяжении нескольких десятилетий. Пионером создания хроматографии в СССЗ как научного направления стал заведующий кафедрой физической и коллоидной химии Тимирязевской сельскохозяйственной академии (ТСХ) профессор Евгений Никитович Гапон (1891-1950). Значимость хроматографии в 1950 году в области научных и прикладных исследований была подтверждена созданием специальной лаборатории в Институте физической химии АН СССР. Первым научным руководителем лаборатории хроматографии был назначен профессор Константин Васильевич Чмутов. Под его руководством были изучены закономерности статики, динамики и кинетики на цеолитах и ионитах с целью внедрения хроматографических процессов в производство. После ухода из жизни в 1979 году Константина Васильевича достойным продолжателем его научных исследователей стал д.х.н. Олег Георгиевич Ларионов (1932-2013). О.Г. Ларионовым и его сотрудниками были выполнены основополагающие работы в области жидкостно-адсорбционной хроматографии, барохроматографии и хроматографического титрования. В 1984 году лаборатория физико-химических основ хроматографии пополнилась сотрудниками безвременно ушедшего всемирно известного физико-химика д.х.н. Андрея Владимировича Киселева Любовью Дмитриевной Беляковой, Юрием Анатольевичем Эльтековым, Натальей Петровной Платоновой. В 2004 году лаборатория пополнилась учеными масс-спектроскопистами из лаборатории спектроскопии ИФХЭ РАН. Одним из них был д.х.н. Алексей Константинович Буряк, который стал заведующим новой объединенной лаборатории физико-химических основ хроматографии и хроматомасс-спектроскопии. В настоящее время в лаборатории ведутся исследования по совершенствованию методов удерживания в условиях газовой хроматографии, а также выполняется теоретическое моделирование и экспериментальная проверка удерживания на углеродных хроматографических сорбентах для жидкостной и газовой хроматографии. Один из методов предсказания газохроматографических индексов удерживания на основе структуры аналита лег в основу современных методов искусственного интеллекта (в глубоких сверточных нейронных сетях).

Characterization of Drug-Polymer Adsorption Isotherms in Body-on-a-Chip Systems by Inverse Liquid-Solid Chromatography.

Body-on-a-chip and human-on-a-chip systems are currently being used to augment and could eventually replace animal models in drug discovery and basic biological research. However, hydrophobic molecules, especially therapeutic compounds, tend to adsorb to the polymer materials used to create these microfluidic platforms, which may distort the dose-response curves that feed into pharmacokinetic/pharmacodynamic (PK/PD) models, which translate preclinical data into predictions of clinical outcomes. Inverse liquid-solid chromatography paired with a numerical optimization based on the Langmuir model of adsorption was used to characterize the adsorption isotherm parameters of drugs to polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA), polymers commonly used in these platforms. The adsorption isotherms were then compared against concentration measurements of drugs recirculated in these platforms. This research further illustrates the point that by quantifying drug or drug candidate interactions before system dosing and including this data in the PK/PD models, then polymers used in these platforms need not be limited to "less-adsorbing" materials.

Identification of petrogenic produced water components as acetylcholine esterase inhibitors

Effect-directed analysis (EDA) was applied to identify acetylcholine esterase (AChE) inhibitors in produced water. Common produced water components from oil production activities, such as polycyclic aromatic hydrocarbons (PAHs), alkylphenols, and naphthenic acids were tested for AChE inhibition using a simple mixture of PAHs and naphthenic acids. Produced water samples collected from two offshore platforms in the Norwegian sector of the North Sea were extracted by solid phase extraction and fractionated by open-column liquid solid chromatography and high-performance liquid chromatography (HPLC) before being tested using a high-throughput and automated AChE assay. The HPLC fractions causing the strongest AChE inhibition were analysed by gas chromatography coupled to a high-resolution time-of-flight mass spectrometry (GC-HR-ToF-MS). Butylated hydroxytoluene and 4-phenyl-1,2-dihydronaphthalene were identified as two produced water components capable of inhibiting AChE at low concentrations. In order to assess the potential presence of such compounds discharged into aquatic ecosystems, AChE activity in fish tissues was measured. Saithe (Pollachius virens) caught near two offshore platforms showed lower enzymatic activity than those collected from a reference location. Target analysis of saithe did not detected the presence of these two putative AChE inhibitors and suggest that additional compounds such as PAHs, naphthenic acids and yet un-identified compounds may also contribute to the purported AChE inhibition observed in saithe.

Evaluation of various techniques for separation of non-polar modifier concentrates from petroleum waxy by-products

Two petroleum waxy by-products (light and middle slack wax crudes) were evaluated for separation of non-polar modifiers by using different techniques. The results showed that, the light slack wax is selected as a suitable wax for separation of n-alkanes with even number of carbon atoms ranging from C20 to C26 for their high n-paraffin contents and can be used as non-polar structural modifiers. Different separation techniques; multistage fractional crystallization and liquid–solid chromatography; followed by the urea adduction technique have been used to separate non-polar modifier concentrates from the light slack wax crude. The light slack wax, its saturate components, the hard wax fractions isolated from light slack wax by the multistage fractional crystallization technique and their adducts were analyzed by GC to characterize and compare the produced components. The resulting data reveal that, the adducts of light slack wax and its saturate components; can be used as non-polar modifier concentrates of low carbon atoms (C20+C22). From an economic point of view, the light slack wax adduct is selected as a non-polar modifier concentrate whereas, the separation step can be neglected to save energy. Meanwhile, the adduct of the hard wax isolated at 30°C can be used as the preferable non-polar modifier concentrate of the high carbon number atoms (C24+C26).

Determination of triazine herbicides in vegetables by ionic liquid foam floatation solid phase extraction high performance liquid chromatography

The ionic liquid foam floatation solid phase extraction was established and applied to the extraction of six triazine herbicides, including desmetryn, secbumeton, terbumeton, terbuthylazine, dimethametryn and dipropetryn, in vegetable samples. To obtain the optimized experimental parameters, the effects of pH value of sample solution, the type and concentration of ionic liquid, the flow rate of carrier gas, foam floatation time, the type of solid phase extraction cartridge, the type and volume of elution solvent on the recoveries of the analytes were examined. The high performance liquid chromatography was applied to the determination of the analytes. Under the optimized experimental conditions, the linearities for determining the analytes were satisfactory and the limits of detection for desmetryn, secbumeton, terbumeton, terbuthylazine, dimethametryn and dipropetryn were 2.50, 1.75, 2.76, 1.87, 1.36 and 1.44μgkg(-1), respectively. The recoveries of the analytes ranged from 78.64% to 104.37% and the relative standard deviations ranged from 1.44 to 6.45%. The real samples were analyzed and the results were satisfactory.

Supercritical Carbon Dioxide Extraction of Aromatic Turmerone from Curcuma longa Linn. Induces Apoptosis through Reactive Oxygen Species-Triggered Intrinsic and Extrinsic Pathways in Human Hepatocellular Carcinoma HepG2 Cells

The mechanisms underlying the antiproliferative and antitumor activities of aromatic turmerone (ar-turmerone), a volatile turmeric oil isolated from Curcuma longa Linn., have been largely unknown. In this study, 86% pure ar-turmerone was extracted by supercritical carbon dioxide and liquid-solid chromatography and its potential effects and molecular mechanisms on cell proliferation studied in human hepatocellular carcinoma cell lines. Ar-turmerone exhibited significant antiproliferative activity, with 50% inhibitory concentrations of 64.8 ± 7.1, 102.5 ± 11.5, and 122.2 ± 7.6 μg/mL against HepG2, Huh-7, and Hep3B cells, respectively. Ar-turmerone-induced apoptosis, confirmed by increased annexin V binding and DNA fragmentation, was accompanied by reactive oxygen species (ROS) production, mitochondrial membrane potential dissipation, increased Bax and p53 up-regulated modulator of apoptosis (PUMA) levels, Bax mitochondrial translocation, cytochrome c release, Fas and death receptor 4 (DR4) augmentation, and caspase-3, -8, and -9 activation. Exposure to caspase inhibitors, Fas-antagonistic antibody, DR4 antagonist, and furosemide (a blocker of Bax translocation) effectively abolished ar-turmerone-triggered apoptosis. Moreover, ar-turmerone stimulated c-Jun N-terminal kinase (JNK) and extracellular signal-related kinase (ERK) phosphorylation and activation; treatment with JNK and ERK inhibitors markedly reduced PUMA, Bax, Fas, and DR4 levels and reduced apoptosis but not ROS generation. Furthermore, antioxidants attenuated ar-turmerone-mediated ROS production; mitochondrial dysfunction; JNK and ERK activation; PUMA, Bax, Fas, and DR4 expression; and apoptosis. Taken together, these results suggest that ar-turmerone-induced apoptosis in HepG2 cells is through ROS-mediated activation of ERK and JNK kinases and triggers both intrinsic and extrinsic caspase activation, leading to apoptosis. On the basis of these observations, ar-turmerone deserves further investigation as a natural anticancer and cancer-preventive agent.

Cromatografia líquido-sólido aplicada à análise de petróleo

This chapter of “Pillars of Chromatography” describes the activities in the area of petroleum analysis that started at the end of the 19 th century, with emphasis on those that applied processes similar to those of liquidsolid chromatography (LSC) even before the work of Tswett was well known. These efforts continued until the middle of the 20 th century when other separation techniques began to substitute determinations made by LSC.

Preparation of Passion Fruit-Typical 2-Alkyl Ester Enantiomers via Lipase-Catalyzed Kinetic Resolution

The preparation of ester enantiomers (acetates, butanoates, hexanoates and octanoates) of the secondary alcohols 2-pentanol, 2-heptanol and 2-nonanol via lipase-catalyzed kinetic resolutions was investigated. Conversion rates and stereochemical courses of esterification and hydrolysis reactions catalyzed by commercially available enzyme preparations were followed for the homologous series of these passion fruit-typical 2-alkyl esters by capillary gas chromatography using heptakis(2,3-di-O-methyl-6-O-tert-butyldimethylsilyl)-beta-cyclodextrin as chiral stationary phase. An efficient method was developed to prepare the ester enantiomers via lipase-catalyzed esterifications: optically pure (R)-2-alkyl esters (ee > 99.9%) were obtained by esterification of the racemic alcohols with enantioselective Candida antarctica lipase B (immobilized) as catalyst. The subsequent esterification of the unreacted alcohols using lipase from Candida cylindracea yielded the optically enriched (S)-esters (ee > 81.4%). The separation of the products via liquid solid chromatography using a mixture of silica gel and aluminum oxide (basic) resulted in high chemical purities and yields (> 40 mol %).

Separation of Bovine Serum Albumin Using Chromatographical Column: Parameters and Simulation

A liquid-solid chromatography of Bovine Serum Albumin (BSA) on (diethylaminoethyl-cellulose) DEAE-cellulose adsorbent is worked experimentally, to study the effect of changing the influent concentration of (0.125, 0.25, 0.5, and 1 mg/ml) at constant volumetric flow rate Q=1ml/min. And the effect of changing the volumetric flow rate (1, 3, 5, and 10 ml/min) at constant influent concentration of Co=0.125mg/ml. By using a glass column of (1.5cm) I.D and (50cm) length, packed with adsorbent of DEAE-cellulose of height (7cm). The influent is introduced in to the column using peristaltic pump and the effluent concentration is investigated using UV-spectrophotometer at 30oC and 280nm wavelength. A spread (steeper) break-through curve is gained at lean feed concentration of 0.125mg/ml, while the flow rate greater than (3ml/min) is almost the same. So it is butter to work at low volumetric flow rate between (1-3) ml/min. The equilibrium-dispersion model of liquid-solid chromatography for a binary mixture, related with Langmuir isotherm correlation is used in the modeling of this work. The resulting model is solved numerically by using MATLAB V.6.5 program.

Compositional Changes of Hydrotreated Naphthenic Rubber Base Oil Under High Temperature

This article discusses the compositional changes of hydrotreated naphthenic rubber base oil under high temperature. First, we adopted liquid–solid chromatography to separate the initial oil and the heated oil into three different fractions (i.e., saturates, aromatics, and polars). Next, each fraction's compositional change was respectively evaluated through a series of instrument technology including gas chromatography-mass spectroscopy (GC-MS), infrared spectroscopy (IR), and x-ray photoelectron spectroscopy (XPS). The results show that under high temperature, the heated sample exhibits a decrease in the saturate and aromatic fractions concomitant with an increase in the polar fraction. For saturates, the content of alkanes in the heated sample exhibits a relatively substantial decrease. On the other hand, the content of cycloalkanes shows a little increase in trend, and the heated oil sample exhibits a decrease in aromatics. Regarding polars, a relatively large amount of oxygen-containing compounds such as hydroxyl, carbonyl, and carboxyl groups was formed under high temperature. XPS data show that a type of S 2pa compounds in the initial oil disappears and could be converted to SO42−. A part of polar compounds in the heated oil could come from aromatic thermo-oxidation in the initial oil.

Design and operation of a modified silica gel column chromatography

Liquid–solid chromatography (LSC) is the oldest of the various liquid chromatography methods. Despite the fact that high-performance liquid chromatography (HPLC) operation leads to better separation and analysis, classical column chromatography and thin-layer chromatography (TLC) are still widely practiced because of their convenience. In this study, a modified silica gel column chromatography was designed with the objective of reducing the amount of solvent required to achieve the same degree of separation as the classical silica gel column chromatography. The separation of squalene and fatty acid steryl esters (FASEs) from non-polar lipid fraction (NPLF) of soybean oil deodorizer distillate (SODD) was employed as a model system to test the effectiveness of this new design. Modified silica gel column chromatography process is feasible from economic point of view compare to classical silica gel column chromatography because it significantly reduces the amount of solvent and time required to achieve the same degree of separation. By employing modified silica gel column chromatography to obtain the squalene-rich fraction, the mobile phase volume and elution time required as fractions of those needed in classical silica gel column chromatography are 1/73 and 1/18, respectively. To obtain the FASEs-rich fraction, the corresponding mobile phase volume and elution time are 1/221 and 1/23, respectively of those needed in classical silica gel column chromatography.

Discoloration of Hydrotreated Naphthenic Rubber Base Oil at High Temperature

In this article, the reasons for discoloration of hydrotreated naphthenic rubber base oil under high temperature were studied in detail. In order to define compositional factors associated with the color deterioration, firstly liquid-solid chromatography was used to separate hydrotreated naphthenic rubber base oil into five different fractions, i.e., saturates, monoaromatics, diaromatics, polyaromatics, and polars. Then color change of each fraction was evaluated under high temperature. The results of the test indicate that polyaromatics and polars are the main precursor of color and deposits, respectively, and the composition of polyaromatics was characterized by elemental analysis, gas chromatography mass spectrometry (GC-MS) and atmospheric pressure chemical ionization mass spectrometer (APCI/MS).

Compositional Changes in Hydrotreated Naphthenic Oil under Ultraviolet Radiation

Compositional changes of hydrotreated naphthenic oil during ultraviolet (UV) radiation were studied in detail. First, liquid–solid chromatography was used to separate the initial oil and the UV-irradiated oil into three different fractions: saturates, aromatics, and polars. Then, each fraction's compositional changes were evaluated using a series of instrument technologies including gas chromatography-mass spectroscopy (GC-MS), infrared spectroscopy (IR), atmospheric pressure chemical ionization mass spectroscopy (APCI/MS), and X-ray photo electron spectroscopy (XPS), respectively. The results show that after UV radiation, the UV-irradiated sample exhibited a decrease in saturates concomitant with an increase in the aromatic and polar fractions. For saturates and aromatics, the UV-irradiated sample exhibited a decrease in alkanes, diaromatics, and polyaromatics concomitant with an increase in other aromatics. The UV light had no significant effect on the cycloalkanes. For polars, a relatively large amount of oxygen-containing compounds, such as hydroxyl, carbonyl, and carboxyl groups, was formed in the presence of UV light. XPS data show that a type of S 2pa compound in the initial oil disappears and could be converted to SO4 2−. No obvious changes of molecular weight distribution were observed. A part of polar compounds in the UV-irradiated oil might come from aromatic photooxidation in the initial oil.

Effect of trace residual ionic impurities on the response of chemiresistor sensors with dithiol-linked monolayer-protected gold (nano)clusters as sensing interfaces

Column liquid–solid chromatography was used to remove residual impurities of isolated n-octanethiol (C 8H 17SH) monolayer-protected gold nano-clusters (MPCs) which were synthesized by a Brust two-phase method. Three-dimensional (3D) cross-linked MPC films were prepared directly on interdigitated electrodes to form chemiresistor sensors through the exchange reactions of the chromatographically purified MPCs with 1,6-hexanedithiol (HDT) or 1,4-benzenedimethanethiol (BDT). Ionic current induced by trace residual ionic impurities in MPCs was qualitatively detected by comparing the resistance responses of the sensors interfaced with the chromatographically purified and unpurified MPC films by employing volatile organic compounds (VOCs) and water vapor as probes, respectively. The existence of the ionic current significantly decreases the sensor sensitivities to VOCs. As for water vapor with high permittivity, the ionic current totally distorted the resistance responses from positive to negative with increasing humidity. Capacitance was also measured to characterize the permittivity change. The effect of ionic current on capacitance was not obvious. The humidity effects on the sensor responses to VOCs were also investigated. Fewer effects were observed on the higher hydrophobic compounds. A ternary sensor array was constructed with C 8Au MPCs, HDT and BDT cross-linked MPC films as sensing interfaces. The response pattern showed that the sensor array could discriminate VOCs with different functional groups. The as-prepared sensor showed the same sensitivities as the acoustic wave sensors.

Supercritical carbon dioxide extraction of turmeric oil from Curcuma longa Linn and purification of turmerones

This study investigates separation and purification of three turmerones from the turmeric oil extracted by supercritical carbon dioxide. Nearly, 800 g of supercritical carbon dioxide extraction of 75 g of 0.42 mm turmeric powders at 333 K and 300 bar obtained 6.98 wt% turmeric oil within 2.5 h. A response-surface methodology is adopted for optimizing supercritical carbon dioxide extraction to disclose that the combination of 320 K and 26 MPa gives an optimum production of turmeric oil containing 71 wt% purity of three turmerones. Subsequently, a normal phase silica gel 60 column is employed to separate and purify three major turmerones from the turmeric oil extracted by supercritical carbon dioxide. The 86 wt% purity of Ar-turmerone and 81 wt% purity of α + β-turmerone have been separated, collected, and identified by liquid–solid chromatography, NMR qualification, and HPLC quantification, respectively.

Comparison of adsorption in liquid-solid chromatography on the basis of different models of retention

Two models of retention in liquid adsorption chromatography have been evaluated. Terms related to adsorption from two equations based on different retention models were compared. The terms were calculated for selected substances in four chromatographic systems with a different polar modifier. Analysis of the data has proved the comparability of the terms and that they can be used interchangeably to describe adsorption phenomena. A regular relationship was found between the terms.

Prediction of Retention in Liquid-Solid Chromatography with Ternary Mobile Phases

The method for the prediction of capacity factors in ternary mobile phases is presented. The adsorption mechanism of retention is considered. The simple theoretical equations are proposed for mobile phases for which the ratio of mole fractions of the weaker solvents remains fixed. The relations between parameters characterizing retention in ternary and binary mobile phases are discussed. The theoretical model is verified for numerous solutes and different mobile phases.