Modelovanje retencionog ponašanja liganada imidazolinskih i serotoninskih receptora u uslovima ekološki bezbedne SFC tehnike

A possibility of predicting retention behaviour without a large number of preliminary experiments is a significant segment of theoretical and experimental investigations. By using an appropriate design to define experimental conditions (Design of Experiments, DoE), the retention behaviour of compounds can be described as a function of the most important parameters of chromatographic system. Further, the DoE methodology has shown successful applicability to modeling retention under the environmentally friendly Supercritical Fluid Chromatography (SFC) conditions (1). In the last decades, robustness of the SFC instruments has been improved in order to minimize ecological risks, and routine application of the SFC technique has been introduced into many pharmaceutical strategies (e.g., the Good Manufacturing Practice, GMP) (2). Therefore, the aim of our study was to define the influence of the main chromatographic factors on the retention behaviour of fourteen imidazoline and serotonin receptor ligands under the SFC conditions. Using the Central Composite Design (CCD) approach, retention characteristics (k) of the test compounds were examined on the mixed-mode stationary phase, with the mixture of supercritical CO2 and methanolic ammonium-formate (with an addition of 0.1% formic acid) used as mobile phase. We took into the consideration the influence of the following factors: volume fraction of methanol in mobile phase (20-30 %), ammonium-formate concentration (15-25 mM), and temperature deviation (20-30 °C). The most important chromatographic factors were selected by the step-wise multilinear regression (MLR), and their statistical significance was assessed using the ANOVA analysis. Based on the results obtained, it was established that the retention characteristics were significantly influenced by changing the methanol and ammonium-formate concentrations in mobile phase (r > 0.90, p 0.98) was observed, when the theoretically predicted logk values for 35% and 15% volume fraction of methanol in mobile phase were compared with the experimental ones. The obtained results confirm successful applicability of the experimental design methodology in order to perform a minimum number of experiments, as demonstrated upon an example of modeling and predicting the retention behaviour of imidazoline and serotonin receptor ligands under the SFC conditions.Mogućnost predviđanja retencije u odsustvu velikog broja prethodnih eksperimenata, značajan je segment teorijskih i eksperimentalnih ispitivanja. Odgovarajućim dizajnom eksperimentalnih uslova (Design of Experiments, DoE), a na osnovu minimalnog broja eksperimenata, može se definisati retenciono ponašanje jedinjenja u funkciji najznačajnijih parametara hromatografskog sistema. Primena DoE metodologije je takođe zabeležena i prilikom modelovanja retencije u uslovima ekološki bezbedne, superkritične fluidne hromatografije (Supercritical Fluid Chromatography, SFC) (1). Zbog minimalnih ekoloških rizika, robusnost SFC instrumenata je poboljšana, a rutinska primena SFC tehnike je uvedena i u regulatorne farmaceutske propise (npr. dobra proizvođačka praksa; Good Manufacturing Practice-GMP) (2). Na osnovu toga, cilj ovog istraživanja obuhvatio je definisanje uticaja najznačajnijih faktora hromatografskog sistema na retenciono ponašanje 14 odabranih liganada imidazolinskih i serotoninskih receptora na mixed-mode stacionarnoj fazi u SFC uslovima. Uticaj zapreminskog udela metanola (20-30 %), koncentracije amonijum-formijata (15-25 mM) i temperature (20-30 °C) na vrednosti retencionih faktora (k) odabranih liganada imidazolinskih i serotoninskih receptora je ispitana primenom centralnog kompozitnog dizajna (Central Composite Design, CCD) na mixed-mode stacionarnoj fazi. Kao mobilna faza korišćena je smeša superkritičnog CO2 i metanolnog rastvora amonijum-formijata uz dodatak 0,1% mravlje kiseline. Najznačajniji hromatografski faktori su izdvojeni step-wise postupkom u višestrukoj linearnoj regresionoj analizi (Multiple Linear Regression, MLR), a njihova statistička značajnost je procenjena primenom ANOVA testa. U konstruisanim retencionim modelima, zapremina metanola i koncentracija pufera su pokazale najveći uticaj na retenciono ponašanje testiranih jedinjenja (r > 0,90; p < 0,05), Slika 1. U koliko se teorijski predviđene logk vrednosti uporede sa eksperimentalno dobijenim vrednostima na 35% i 15% zapreminskim udelima metanola u mobilnoj fazi, uočava se da je prisutan visok stepen slaganja (r > 0,98). Dobijeni rezultati potvrđuju uspešnu primenljivost metodologije eksperimentalnog dizajna u cilju izvođenja minimalnog broja eksperimenata, prilikom modelovanja i predikcije retencionog ponašanja liganda imidazolinskih i serotoninskih receptora u SFC sistemima.Drugi naučni simpozijum Saveza farmaceutskih udruženja Srbije sa međunarodnim učešćem, 28. 10. 2021. Beogra

Countercurrent chromatography in analytical chemistry (IUPAC technical report)

© 2009 IUPACCountercurrent chromatography (CCC) is a generic term covering all forms of liquid-liquid chromatography that use a support-free liquid stationary phase held in place by a simple centrifugal or complex centrifugal force field. Biphasic liquid systems are used with one liquid phase being the stationary phase and the other being the mobile phase. Although initiated almost 30 years ago, CCC lacked reliable columns. This is changing now, and the newly designed centrifuges appearing on the market make excellent CCC columns. This review focuses on the advantages of a liquid stationary phase and addresses the chromatographic theory of CCC. The main difference with classical liquid chromatography (LC) is the variable volume of the stationary phase. There are mainly two different ways to obtain a liquid stationary phase using centrifugal forces, the hydrostatic way and the hydrodynamic way. These two kinds of CCC columns are described and compared. The reported applications of CCC in analytical chemistry and comparison with other separation and enrichment methods show that the technique can be successfully used in the analysis of plants and other natural products, for the separation of biochemicals and pharmaceuticals, for the separation of alkaloids from medical herbs, in food analysis, etc. On the basis of the studies of the last two decades, recommendations are also given for the application of CCC in trace inorganic analysis and in radioanalytical chemistry

New Methods for Improvement of Sensitivity, Selectivity and Expressivity of Two-Column Ion Chromatography

Available from VNTIC / VNTIC - Scientific & Technical Information Centre of RussiaSIGLERURussian Federatio

Retention mechanisms of imidazolin and piperazine-related compounds in non-aqueous hydrophilic interaction and supercritical fluid chromatography based on chemometric design and analysis

The experimental design methodology based on central composite design of experiments was applied to compare the retention mechanisms in supercritical fluid chromatography (SFC) and non-aqueous hy- drophilic interaction liquid chromatography (NA-HILIC). The selected set consists of 26 compounds that belong to imidazoline and serotonin receptor ligands. The different chemometric tools (multiple linear regression, principal component analysis, parallel factor analysis) were used to examine the retention, as well as to identify the most significant retention mechanisms. The retention mechanism was investigated on two different stationary phases (diol, and mixed-mode diol). In NA-HILIC, the mobile phase contains acetonitrile as a main component, and methanolic solution of ammonium formate (+ 0.1% of formic acid) as a modifier. The same mobile phase modifier was used in SFC, with a difference in the main component of the mobile phase which was CO2. The retention behaviour differs significantly between HILIC and SFC conditions. The retention pattern in HILIC mode was more partition-like, while in SFC the solute-sorbent interactions allowed retention. The retention mechanism between mixed-mode diol and the diol phases varies depending on the applied chromatographic mode, e.g., in HILIC the type of stationary phase significantly affects the elution order, while in SFC this was not the case. The HILIC retention behaviour was influenced by the number of tertiary amines-aliphatic, and N atom-centred fragments in tested compounds. On the other hand, the number of pyrrole and pyridine rings in the structure of the compound showed correlation with their SFC retention, simultaneously increasing the molecular weight and rapid elution of larger compounds. It was found that temperature surprisingly plays a major role in SFC mode. The increase in temperature reduces the relative contribution of enthalpy factors to total retention, so the separation in SFC was more entropy-controlled. For further pharmaceutical research and optimization, the SFC would be considered more beneficial compared to HILIC since it gives good selectivity in separation of chosen impurities

Bovine serum albumin adsorbed on eremomycin and grafted on silica as new mixed-binary chiral sorbent for improved enantioseparation of drugs

A new silica-based, mixed-binary chiral sorbent grafted with the macrocyclic antibiotic eremomycin and bovine serum albumin (BSA) was obtained. The sorbent-filled high-performance liquid chromatography column was capable of enantioseparation of racemic drugs, such as profens, in reversed-phase-chromatography mode. The mixed-binary eremomycin-BSA-sorbent showed better capability for profens enantioseparation as compared with a sorbent containing eremomycin only. BSA grafted onto the sorbent surface significantly reduced retention times of other proteins from the analyte solution, and free proteins (including BSA) injected as analytes were not retained on the column, and subsequently eluted with a dead volume. The drastic difference observed in the binding of profens and other proteins using the sorbent was tested for determination and enantioseparation of profens in artificial-urine solutions

INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY ANALYTICAL CHEMISTRY DIVISION* COUNTERCURRENT CHROMATOGRAPHY IN ANALYTICAL CHEMISTRY (IUPAC Technical Report) Prepared for publication by

Republication or reproduction of this report or its storage and/or dissemination by electronic means is permitted without the need for formal IUPAC permission on condition that an acknowledgment, with full reference to the source, along with use of the copyright symbol ©, the name IUPAC, and the year of publication, are prominently visible. Publication of a translation into another language is subject to the additional condition of prior approval from the relevant IUPAC National Adherin

Stability of some biologically active substances in extracts and preparations based on ST. John's Wort (Hypericum Perforatum L.) and sage (Salvia Officinalis L.)

Quality, authenticity and stability control of medicinal plant materials and preparations based on them is an important challenge in industries using substances and materials derived from plants. St. John’s wort (Hypericum perforatum L.) and sage (Salvia officinalis L.) are one of the most common and best-selling medicines in the world. They are composed of phloroglucinols and diterpenes possessing pharmacological properties. However, some of the compounds (hyperforin, carnosic acid, etc.) determining these qualities decompose under the influence of various physical and chemical factors with the formation of stable and unstable intermediates. Considering the importance of utilization of these plants, the stability of hyperforin, carnosic acid and other compounds in their extracts and preparations during extraction and storage was studied in this work. Extracts and preparations were studied by high performance liquid chromatography (HPLC) with diode-array and mass spectrometric detection. Plant extracts were obtained by heating (HE) as well as using ultrasonic (USE), microwave (MWE) and supercritical (SSE) extraction. The stability of hyperforins, their degradation, as well as the relationship between hyperforin and furohyperforin contents in extracts and preparations based on H. perforatum L. during storage were studied. Hyperforin to furohyperforin ratio in the extracts ranged from 18 to 5 depending on the origin of the medicinal plant material. The stability and transformation of carnosic acid was evaluated, the relationship between carnosic acid and carnosol contents and conditions of sample preparation and storage as well as industrially manufactured preparations based on S. officinalis L. was revealed. The possibility of applicability of hyperforin to furohyperforin ratio in H. perforatum L. and carnosic acid to carnosol ratio in S. officinalis L. was shown to confirm the quality of extracts and preparations on their basis. Since rutin to hyperforin ratio in H. perforatum L. is constant, this indicator can be used to confirm the quality and authenticity of the feedstock, regardless of where the plant grows