Aqueous-organic Mobile Phases Research Articles

Digital light processing 3D printing of microfluidic devices targeting high-pressure liquid-phase separations.

This paper focuses on 3D printing using digital light processing (DLP) to create microchannel devices with inner diameters of100, 200, and 500 µm and cater flow-through applications within the realm of analytical chemistry, in particular high-pressure liquid chromatographic separations. Effects of layer thickness and exposure time on channel dimensions and surface roughness were systematically investigated. Utilizing a commercially accessible 3D printer and acrylate resin formulation, we fabricated 100-500 µm i.d. squared and circular channel designs minimizing average surface roughness (< 20%) by applying a 20-µm layer thickness and exposure times ranging from 1.1 to 0.7s. Pressure resistance was measured by encasing microdevices in an aluminum chip holder that integrated flat-bottom polyetheretherketon (PEEK)nanoports allowing to establish the micro-to-macro interface to the HPLC instrument. After thermal post-curing and finetuning the clamping force of the chip holder, a maximum pressure resistance of 650bar (1.5% RSD) was reached (n = 3). A polymer monolithic support structure was successfully synthesized in situ with the confines of a 500 µm i.d. 3D printed microchannel. A proof-of-concept of a reversed-phase chromatographic gradient separation of intact proteins is demonstrated using an aqueous-organic mobile-phase with isopropanol as organic modifier.

Сравнение двух типов подвижных фаз для определения витаминов группы В методом тонкослойной хроматографии

Thin-layer chromatography (TLC) has been used to study the influence of a number of factors (the nature of the stationary phase, the nature and concentration of the organic solvents and surfactants, the pH of the buffer solution) on the chromatographic characteristics of B vitamins: B 1 (thiamine), B6 (pyridoxine), B12 (cyanocobalamin). The stationary phases were plates with polar (Sorbfil on a polymer (highperformance plates, HTLC) and aluminum substrates), weakly polar (Polyamide-6), and nonpolar (RP-18 on an aluminum substrate) sorbents. As micellar mobile phases – micellar solutions of cetylpyridinium chloride in the concentration range 5–10-4 – 5–10-1 M, sodium dodecyl sulfate in the concentration range 2,5–10-4 – 5–10-1 М. It has been established that among aqueous-organic mobile phases (MF) the best results have been obtained for MF of the composition acetonitrile – water (15:385) on polar high-performance plates. More effective than acetonitrile – water is the PF of the composition acetonitrile – cetylpyridinium chloride (15:85) in the presence of a phosphate buffer solution with pH = 3. For the last PF, TLC determination of vitamins B1, B6, B12 in pharmaceutical preparations with a Sr value of interval 0.01–0.06 has been developed.

Chromatographic behavior of polar compounds in the transition between reversed-phase and submicellar/micellar liquid chromatography

Micellar liquid chromatography (MLC) is a reversed-phase liquid chromatography (RPLC) mode employing a surfactant, typically sodium dodecyl sulfate (SDS), which is biodegradable, in an aqueous or aqueous-organic mobile phase above its critical micellar concentration (CMC). Under these conditions, substantial alterations in retention, selectivity and peak profile occur in comparison to RPLC using conventional hydro-organic mobile phases. These changes arise from the presence of micelles in the mobile phase and the adsorption of surfactant on the stationary phase. In this work, the chromatographic performance of polar compounds of diverse nature is investigated using mobile phases containing SDS below and above its CMC in the presence of acetonitrile. Three nucleosides, four diuretics, and four sulfonamides, all of biomedical and pharmaceutical significance and possessing distinct acid-base characteristics, were chosen as probe compounds. Modifications in retention and peak shape were investigated using experimental conditions that enable the transition from submicellar to micellar conditions. A comparison was also made with conventional RPLC. Analysing the polar compounds with RPLC under low submicellar or micellar conditions significantly decreases the consumption of organic solvent in comparison to hydrophilic liquid chromatography (HILIC).

Simultaneous determination of enantiomeric and organic impurities of vildagliptin on a cellulose tris(3-chloro-4-methylphenylcarbamate) column under revered-phase conditions

A new, reversed-phase HPLC (RP-HPLC) method was developed for the simultaneous determination of the dipeptidyl-peptidase-IV-inhibitor antidiabetic drug vildagliptin (VIL) enantiomeric impurity and four other achiral related impurities. An initial screening was performed on five polysaccharide-type chiral stationary phases (Lux Amylose-1, Lux Amylose-2, Lux-Cellulose-1, Lux-Cellulose-2, Lux-Cellulose-3) in polar organic mode with methanol, ethanol, 2-propanol, or acetonitrile containing 0,1% diethylamine as mobile phase to identify the best conditions for the separation of VIL enantiomers. Lux-Cellulose-2 column was found to provide the best chiral resolution for VIL enantiomers. Further experiments were conducted using different aqueous-organic mobile phases to achieve the simultaneous chiral-achiral separation of the selected compounds. Experimental design-based optimization was performed by using a face-centered central composite design. The optimal separation conditions (Lux Cellulose-2 stationary phase, 45 °C, mobile phase consisting of methanol/water/diethylamine 80:20:0.2 (v/v/v), and 0.45 mL/min flow rate) provided baseline separation for all 6 compounds. The optimized method was validated according to the ICH guideline and proved to be reliable, specific, linear, precise, and accurate for the determination of at least 0.1% for all impurities in VIL samples. The validated method was applied for determinations from a commercially available drug formulation and proved to be suitable for routine quality control of both enantiomeric and organic impurities of VIL.

A New Definition of the Stationary Phase Volume in Mixed-Mode Chromatographic Columns in Hydrophilic Liquid Chromatography.

Polar columns used in the HILIC (Hydrophilic Interaction Liquid Chromatography) systems take up water from the mixed aqueous–organic mobile phases in excess of the water concentration in the bulk mobile phase. The adsorbed water forms a diffuse layer, which becomes a part of the HILIC stationary phase and plays dominant role in the retention of polar compounds. It is difficult to fix the exact boundary between the diffuse stationary and the bulk mobile phase, hence determining the column hold-up volume is subject to errors. Adopting a convention that presumes that the volume of the adsorbed water can be understood as the column stationary phase volume enables unambiguous determination of the volumes of the stationary and of the mobile phases in the column, which is necessary for obtaining thermodynamically correct chromatographic data in HILIC systems. The volume of the aqueous stationary phase, Vex, can be determined experimentally by frontal analysis combined with Karl Fischer titration method, yielding isotherms of water adsorbed on polar columns, which allow direct prediction of the effects of the composition of aqueous–organic mobile phase on the retention in HILIC systems, and more accurate determination of phase volumes in columns and consistent retention data for any mobile phase composition. The n phase volume ratios of 18 columns calculated according to the new phase convention strongly depend on the type of the polar column. Zwitterionic and TSK gel amide and amine columns show especially strong water adsorption.

Green UHPLC Method for Simultaneous Determination of Febuxostat and Diclofenac in Pharmaceutical Dosage Form and Human Plasma

Eco-friendly Ultra-high-performance liquid chromatography (UHPLC) with green aqueous-organic mobile phase was applied for the simultaneous determination of febuxostat (FEB) and diclofenac (DIC) with the composition of water:ethanol (85:15 v/v) utilizing phenomenex Kinetex C18 column (4.6 × 100 mm 2.6 μm), flow rate 1 ml/min and UV detection at 280 nm with linear ranges of 0.4 - 4.0 μg/mL and 0.5 - 5.0 μg/mL for FEB and DIC, respectively. The proposed method was also successfully applied to analyze the two drugs in pharmaceutical dosage form and human plasma. The results obtained were validated and statistically analyzed and found to be in accordance with those given by reported methods. Moreover, the greenness of the developed method is assessed using suitable analytical Eco-Scale and GAPI tools and comparison with the previously published methods have been carried out to indicate the priority of the proposed method. UHPLC is considered eco-friendly method regarding uses of safe solvents, simple, accurate and short time of analysis.

Comparative modelling study on enantioresolution of structurally unrelated compounds with amylose-based chiral stationary phases in reversed phase liquid chromatography-mass spectrometry conditions

Polysaccharide-based chiral stationary phases (CSPs) are the most used chiral selectors in HPLC. These CSPs can be used in normal, polar organic and aqueous-organic mobile phases. However, normal and polar organic mobile phases are not adequate for chiral separation of polar compounds, for the analysis of aqueous samples and for MS detection. In these situations, reversed phase conditions, without the usual non-volatile additives incompatible with MS detection, are preferable. Moreover, in most of the reported chiral chromatographic methods, retention is too large for routine work. In this paper, the chiral separation of 53 structurally unrelated compounds is studied using three commercial amylose-based CSPs -coated amylose tris(3,5-dimethylphenylcarbamate) (Am1), coated amylose tris(5-chloro-2-methylphenylcarbamate) (Am2), and immobilised amylose tris(3-chloro-5-methylphenylcarbamate) (Am3)-. Chiral separations are carried out using acetonitrile/ammonium bicarbonate (pH=8.0) mixtures, reversed mobile phases compatible with MS detection. To provide realistic conditions for routine analysis, maximum retention factors are set to 15. Retention and enantioresolution behaviour of compounds in those CSPs are compared. On the other hand, to compare and describe the resolution ability of these CSPs, 58 structural variables of the compounds are tested to model for the first time a categorical enantioresolution (CRs) for Am1 and Am3 CSPs. Discriminant partial least squares, for one response categorical variable (DPLS1) is used for feature selection, modelling. The final DPLS1 models showed good descriptive ability.

Hydrophilic Liquid Chromatography versus Reversed-Phase Liquid Chromatography in the Absence and the Presence of 1-Hexyl-3-methylimidazolium Chloride for the Analysis of Basic Compounds

In reversed-phase liquid chromatography (RPLC), positively charged basic compounds yield broad and asymmetric peaks, as a result of ionic interactions with free silanols that remain on conventional silica-based columns. Diverse solutions have been proposed to mask the silanophilic activity, which is translated to an improved peak shape. In this work, the chromatographic performance of hydrophilic interaction liquid chromatography (HILIC) was evaluated as an alternative to the addition of an ionic liquid (IL) to the aqueous-organic mobile phase used with RPLC columns, for the analysis of eight β-adrenoceptor antagonists. ILs change the behavior of RPLC stationary phases owing to adsorption on their surface. Meanwhile, in HILIC, a layer of adsorbed water is formed on the stationary phase surface. The association of cationic basic compounds with the adsorbed additive ions, hydrophilic partitioning on the HILIC columns, and other interactions, give rise to complex retention mechanisms. The chromatographic behavior was examined in terms of retention, elution strength, selectivity, peak shape and resolution, using acetonitrile-water mobile phases buffered at pH 3. Both chromatographic modes, RPLC with added IL and HILIC, proved to be a viable solution to the problem of poor peak shape for basic compounds.

Application of NEMI, Analytical Eco-Scale and GAPI tools for greenness assessment of three developed chromatographic methods for quantification of sulfadiazine and trimethoprim in bovine meat and chicken muscles: Comparison to greenness profile of reported HPLC methods

Employing green analytical chemistry approaches to newly developed methods has extremely gained the interest of the analytical community and was intensely established in the past few years. The utilized solvents as well as the amount of produced waste have the chief impact on evaluating the greenness of the method. The present work is devoted to the development and the assessment of the greenness profile of three developed chromatographic methods for the quantitative estimation of sulfadiazine (SDZ) and trimethoprim (TMP) in bovine meat and chicken muscles using three evaluation tools; the “National Environmental Method Index” (NEMI), the “Analytical Eco-Scale” and the “Green Analytical Procedure Index” (GAPI). The developed methods have employed a variety of mobile and stationary phases and offered different quantification ranges. Conventional RP-HPLC with green aqueous-organic mobile phase was applied in Method I with the composition of water: ethanol (90: 10 v/v, pH = 5.5) utilizing a Gemini C18 column (150 × 4.6 mm, 5 µm) with linear ranges of 1–60 μg/mL for SDZ and 1–50 μg/mL for TMP. Micellar liquid chromatography (MLC) as an efficient green alternate was used in Method II with mobile phase composition of 0.1 M SDS, 12% isopropanol in 0.1 N citric acid buffered at pH 5.5 while utilizing an XTerra RP18 column (150 × 3.9 mm, 5 µm) and resulting in a linear range of 0.5–100 μg/mL for both drugs. UPLC-MS/MS as a high throughput analytical technique was utilized in Method III with a mobile phase composed of ammonium acetate: acetonitrile (80: 20 v/v, pH = 5.5) and an Acquity UPLC-BEH C18 column (50 × 2.1 mm, 1.7 μm), where the linear range was 0.1–2 μg/mL for both drugs. Thus, Methods II and III have permitted the estimation of the residues of SDZ and TMP at levels equivalent to their maximum residue limits. The three assessment tools have agreed that Methods II and III are the greenest developed methods, thus, recommending the utilization of MLC and UPLC-MS/MS as green, safe practice for estimating the drugs’ residues in food of animal origin.

Dual-mode hydrophilic interaction normal phase and reversed phase liquid chromatography of polar compounds on a single column.

Adopting a stationary phase convention circumvents problematic definition of the boundary between the stationary and the mobile phase in the liquid chromatography, resulting in thermodynamically consistent and reproducible chromatographic data. Three stationary phase definition conventions provide different retention data, but equal selectivity: (i) the complete solid phase moiety; (ii) the solid porous part carrying the active interaction centers; (iii) the volume of the inner column pores. The selective uptake of water from the bulk aqueous-organic mobile phase significantly affects the volume and the properties of polar stationary phases. Some polar stationary phases provide dual-mode retention mechanism in aqueous-organic mobile phases, reversed-phase in the water-rich range, and normal-phase at high concentrations of the organic solvent in water. The linear solvation energy relationship model characterizes the structural contributions of the non-selective and selective polar interactions both in the water-rich and organic solvent-rich mobile phases. The inner-pore convention provides a single hold-up volume value for the retention prediction on the dual-mode columns over the full mobile phase range. Using the dual-mode monolithic polymethacrylate zwitterionic micro-columns alternatively in each mode in the first dimension of two-dimensional liquid chromatography, in combination with a short reversed-phase column in the second dimension, provides enhanced sample information.

Effect of buffer nature and concentration on the chromatographic performance of basic compounds in the absence and presence of 1-hexyl-3-methylimidazolium chloride

In reversed-phase liquid chromatography, the performance for basic compounds is affected by the interaction of the protonated (cationic) species with the anionic free silanols on the alkyl-bonded stationary phases. Using aqueous-organic mobile phases in the absence of additives, the retention may be too high, and the peaks be broad and asymmetric. The performance is improved by addition to the mobile phase of ionic liquids, from which 1-hexyl-3-methylimidazolium chloride ([C6MIm][Cl]) has especially good characteristics. A recent report has also revealed that the use of the phosphate system as buffer, at varying concentration and pH, may have a significant role in the chromatographic performance of basic compounds, with effects on both retention and peak shape. In this work, this study has been extended to other three buffer systems (acetate, citrate, and formate), at increasing concentrations and pH 3 and 7, in the presence and absence of [C6MIm][Cl]. The results have been compared with those obtained with the phosphate system. The retention increases by addition of larger concentration of all buffers, in both absence and presence of [C6MIm][Cl]. Without additive, peak performance is also enhanced significantly. This effect is minimal in the presence of [C6MIm][Cl], which yields highly symmetrical peaks at all buffer concentrations, due to an effective blocking of the silanol activity.

Development and Validation of GC-MS and HPLC Methods for the Determination of Simvastatin in Tablets and Human Urine

:The present work reports rapid, sensitive and specific methods for determination of simvastatin in tablets and human urine by gas chromatography with mass spectrometry (GC-MS) and high-performance liquid chromatography with UV detection (HPLC-UV). The GC-MS method involved the separation of simvastatin without derivatization prior to analysis using 5% Phenyl Polysilphenylene-siloxane (TR-5MS) column with temperature programming. The EI mass spectrum of simvastatin was characterized by [M]+ at 418 and a base peak at m/z 159. In the HPLC method, the chromatographic behavior of simvastatin in micellar and aqueous-organic mobile phases using a short C8 column was investigated and simvastatin was detected at 240 nm. The methods were validated according to ICH guideline. The GC-MS and HPLC methods were successfully applied for the determination of simvastatin in tablets either alone or co-formulated with ezetimibe. Furthermore, the proposed methods were applied for the determination of simvastatin in human urine as a preclinical toxicology evaluation with no interfering peaks were observed from urine matrix.

1H-Tetrazole-5-amine Immobilized on Substituted Polymer Gel/Silica as a New Stationary Phase for Hydrophilic Interaction Chromatography

1H-Tetrazole-5-amine immobilized on substituted polymer gel/silica as a new stationary phase has been newly suggested for application in hydrophilic liquid chromatography (HILIC). The newly investigated column demonstrated a satisfactory retention of very polar compounds. The column showed mixed separation modes: reversed-phase (RP) in water-rich mobile phases and HILIC at high concentrations of acetonitrile content (> 60–80%) in aqueous–organic mobile phases. A continuous change in retention was observed at decreasing concentration of acetonitrile in water, the rise resulting in characteristic U-shape plots of retention factors versus the concentration of acetonitrile in the mobile phase, with minima corresponding to the transition between the mechanisms controlling the retention. The retention mechanism of the new column was investigated by the models (partitioning and surface adsorption) through adjustment of the water/acetonitrile ratio in the mobile phase, and by the influence of salt concentration, buffer pH, and temperature on the retention of tested analytes. The retention behavior of tested compounds on three different stationary phases (Atlantis HILIC—silica phase; TSKgel Amide-80—amide phase; Kromasil 60-5 DIOL—diol phase) was investigated to compare the selectivity with the new DCpak PTZ HILIC prototype column. The applicability of the new HILIC column for the chromatography of polar compounds was proven by the separation of mixtures of nucleobases (uracil, thymine, guanine, cytosine, and adenine) and organic acids (ascorbic, isoascorbic, pantothenic, and nicotinic acid). The new DCpak PTZ HILIC column could be a good alternative for the separation of the polar compounds.

Mobile phase effects on the retention on polar columns with special attention to the dual hydrophilic interaction–reversed‐phase liquid chromatography mechanism, a review

Hydrophilic interaction liquid chromatography on polar columns in aqueous-organic mobile phases has become increasingly popular for the separation of many biologically important compounds in chemical, environmental, food, toxicological, and other samples. In spite of many new applications appearing in literature, the retention mechanism is still controversial. This review addresses recent progress in understanding of the retention models in hydrophilic interaction liquid chromatography. The main attention is focused on the role of water, both adsorbed by the column and contained in the bulk mobile phase. Further, the theoretical retention models in the isocratic and gradient elution modes are discussed. The dual hydrophilic interaction liquid chromatography reversed-phase retention mechanism on polar columns is treated in detail, especially with respect to the practical use in one- and two-dimensional liquid chromatography separations.

Retention Models on Core-Shell Columns.

A thin, active shell layer on core-shell columns provides high efficiency in HPLC at moderately high pressures. We revisited three models of mobile phase effects on retention for core-shell columns in mixed aqueous-organic mobile phases: linear solvent strength and Snyder-Soczewiński two-parameter models and a three-parameter model. For some compounds, two-parameter models show minor deviations from linearity due to neglect of possible minor retention in pure weak solvent, which is compensated for in the three-parameter model, which does not explicitly assume either the adsorption or the partition retention mechanism in normal- or reversed-phase systems. The model retention equation can be formulated as a function of solute retention factors of nonionic compounds in pure organic solvent and in pure water (or aqueous buffer) and of the volume fraction of an either aqueous or organic solvent component in a two-component mobile phase. With core-shell columns, the impervious solid core does not participate in the retention process. Hence, the thermodynamic retention factors, defined as the ratio of the mass of the analyte mass contained in the stationary phase to its mass in the mobile phase in the column, should not include the particle core volume. The values of the thermodynamic factors are lower than the retention factors determined using a convention including the inert core in the stationary phase. However, both conventions produce correct results if consistently used to predict the effects of changing mobile phase composition on retention. We compared three types of core-shell columns with C18-, phenyl-hexyl-, and biphenyl-bonded phases. The core-shell columns with phenyl-hexyl- and biphenyl-bonded ligands provided lower errors in two-parameter model predictions for alkylbenzenes, phenolic acids, and flavonoid compounds in comparison with C18-bonded ligands.

Separation of enantiomers of chiral weak acids with polysaccharide-based chiral columns and aqueous-organic mobile phases in high-performance liquid chromatography: Typical reversed-phase behavior?

When polysaccharide-based chiral columns are used in combination with aqueous-organic mobile phases for the separation of enantiomers in high-performance liquid chromatography the separation mode is commonly called “reversed-phase” in analogy to achiral separations. In several earlier and recent studies on neutral and basic chiral analytes it was shown by our and other groups that due to multiple type of interactions involved in selector-selectand binding and enantioselective recognition with polysaccharide derivatives, the above mentioned separation system may not always behave like a reversed-phase system. In the present study additional examples of non-reversed-phase behavior are described for the first time for weak acidic chiral analytes. In addition, the reversal of enantiomer elution order was observed again for the first time for several analytes based on water-content in the mobile phase.

Dual Retention Mechanism in Two-Dimensional LC Separations of Barbiturates, Sulfonamides, Nucleic Bases and Nucleosides on Polymethacrylate Zwitterionic Monolithic Micro-Columns

In-house prepared zwitterionic polymethacrylate micro-columns using in situ polymerization of N,N-dimethyl-N-metacryloxyethyl-N-(3-sulfopropyl) ammonium betaine (MEDSA) functional monomer with bisphenol A glycerolate dimethacrylate (BIGDMA) cross-linker provided excellent stability and reproducibility of preparation and separation efficiency of 60,000–70,000 theoretical plates m−1 for small molecules under isocratic conditions. The column showed a dual retention mechanism, reversed-phase (RP) in highly aqueous mobile phases and aqueous normal-phase (HILIC) in acetonitrile-rich mobile phases. This property can be used to obtain complementary separation and combined information on the sample from repeated injections of a sample on a single column, in different mobile phases characteristic for the HILIC and for the RP modes, which is in fact a form of offline two-dimensional chromatography on a single column. The dual retention mechanism has been observed with a variety of columns, however, often with impractically narrow retention range in one of the two modes. To take full advantage from the combined single-column RP–HILIC experiments, the column should provide a sufficiently broad mobile phase interval both in the RP and in the HILIC mode. The BIGDMA-MEDSA micro-columns proved suitable earlier for the combined RP–HILIC separations of some phenolic compounds and flavonoids. In the present work, we investigated the effects of the mobile phase composition on the retention of a variety of polar compounds over full retention range of buffered aqueous acetonitrile mobile phases, to find potentially useful HILIC and RP retention ranges for barbiturates, sulfonamides, nucleosides and nucleic bases. In the HILIC mode, proton donor–acceptor interactions show a major effect on retention and selectivity of separation, whereas the size of the non-polar hydrocarbon part of the sample molecule is the most important factor in the water-rich mobile phases. The sample structure strongly affects the composition of aqueous–organic mobile phases at which the transition between the two retention modes occurs. Of the investigated sample types, barbiturates show better separation under reversed-phase conditions, whereas nucleosides and nucleic bases in the HILIC mode. Aromatic carboxylic acids and sulfonamides can be separated either in the reversed phase or under HILIC conditions, the two separation modes showing complementary selectivity of separation.

Enantiomer separation of acidic chiral compounds on a quinine-silica/zirconia hybrid monolith by capillary electrochromatography

A weak anion-exchanger chiral selector, quinine-incorporated silica/zirconia hybrid monolithic (QUI-S/ZHM) capillary column was prepared by sol–gel technology. The performance of the QUI-S/ZHM column was investigated for enantioresolution of a set of acidic chiral drugs and dinitrobenzoyl (DNB)-amino acids by capillary electrochromatography in aqueous organic mobile phases composed of acetonitrile (ACN) and triethylammonium acetate (TEAA) buffer. Effects of several parameters including the ACN content, concentration and pH of the mobile phase on the chiral separation were examined. Baseline resolutions of all the compounds were obtained in the mobile phase consisting of 70:30 ACN/TEAA (10mM, pH 6) under applied voltage of −10kV at 25°C within 20min.

Usefulness of thin-layer chromatography for the prediction of high-performance liquid chromatographic retention behavior of new 1,2,4-triazole and thiosemicarbazide derivatives

The purpose of this paper was to assess the suitability of thin-layer chromatography (TLC) as a pilot method for high-performance liquid chromatography (HPLC). The new 1,2,4-triazole and thiosemicarbazide derivatives were analyzed by use of reversed-phase (RP)-TLC and RP-HPLC techniques, applying octadecyl silica adsorbents and aqueous-organic mobile phases. Organic modifiers: methanol and acetonitrile were used at appropriate concentrations providing optimal retention factors. For both techniques, retention coefficient k in column chromatography and the retardation factor RF expressing retention in TLC were determined. The experimentally measured parameters were presented in a logarithmic scale as log k and RM, respectively. The constructed relationships between log k and RM allowed determining the possibility of TLC for anticipating HPLC retention behavior.

Micellar liquid chromatography of plant extracts components

Raw materials quality assessment is a very important factor, enabling products creation up to the international standards. In this investigation, the qualitative composition of bioactive plant extracts has been checked. The tested extracts have been obtained by the use of supercritical carbon dioxide extraction and can be utilized as raw materials in a commercial production of a wide range of many different goods. Plant extracts of raspberry (Rubus idaeus), strawberry (Fragaria ananassa), blackcurrant (Ribes nigrum), aronia (Aronia Medik.), Japanese rose (Rosa rugosa Thunb.) seeds, and palmetto palm (Sabal minor) fruit have been examined. In these extracts, saturated, monounsaturated, and polyunsaturated fatty acids as well as polyphenols have been identified using thin-layer chromatography (TLC) with aqueous-organic mobile phases. Appropriate content of these components tends to be a determinant of human organism operation. In our investigation, the plant extract components, especially saturated and unsa...