Monolitinių (ištisinių sorbentų) chromatografinių kolonėlių taikymas fitocheminei analizei

One and a half decade passed since the pioneering work on synthesis and application of non-particulate monolithic stationary phases for liquid chromatography was published by S. Hjertén et al. [S. Hjertén, J.L. Liao, R. Zhang, J. Chromatogr. 473 (1989) 273]. This technique attracted much interest and effort of the researchers developing chromatographic methods and designing chromatographic stationary phases due to several generic qualities of the monolithic (continuous bed) technique. Advantages include: flexibility of the technique in sense of chemistries and functional compositions of the resultant stationary phases; low separation impedance (ratio of pressure drop and efficiency) of monolithic columns; compatibility with micro and nanoformat separations; low time and labour consumption and cost-efficiency. Not surprisingly, these materials attracted interest from phytochemists as plants constitute a complex matrix. However to date, not many successful studies were published in the area of monolithic materials for solving plant metabolomics problems or substituting common particulate materials with monolithic stationary phases in phytochemical analysis. This paper provides an overviewVytauto Didžiojo universiteta

Molecular imprinting and molecular self-assembly techniques : design of new materials for nanochromatographic separations

The emergence of molecular imprinting has its roots in immunology. By the early 1930s, Breinl, Haurowitz and later Pauling proposed a theory explaining the diversity of antibody formation based on specific interactions with certain antigens. This theory was shown to be incorrect and the instructive antibody formation model was abandoned. Nevertheless, later this model was successfully applied by Mosbach and many others and laid the foundation for the molecular imprinting techniques. Molecular imprinting is a rapidly developing field, which takes the advantage of the nanoscale templating […]. It involves nanoscale self-organization of the matter and molecular recognition of imprinted and related molecules. Two general approaches to molecular imprinting exist: covalent and noncovalent imprinting of target molecules. The use of noncovalent interactions between the target molecule and the functional precursors of the solid polymer is more versatile. The noncovalent interactions in the self-assembly step and imprint formation closely mimic the recognition pattern observed in biological systems. Self-assembly process plays an important role for the arrangement of the interaction sites in the polymeric receptors synthesized. [...]Vytauto Didžiojo universiteta

Twenty years of continuous bed (monolithic) techniques : unsurpassed flexibility and success

The pioneering work on synthesis and application of non-particulate stationary phases for liquid chromatography was published in 20 years ago [1]. Numerous publications, growing interest and a number of non-particulate phase products released by several companies, such as CIM Disk (BIA Separations, Ljubljana, Slovenia), CB Silica plate (Conchrom, Bremen, Germany), SepraSorb (Sepragen, San Leandro, California), CIM Tube, CIM Disk (BIA Separations, Ljubljana, Slovenia), UNO (BioRad, Richmond, California), Swift (ISCO, Lincoln, Nebraska), Chromolith, Chromolith CapRod (Merck, Darmstadt, Germany), Monoliths (LC Packings, Amsterdam, The Netherlands), Onyx (Phenomenex, Torrence, California) illustrate an importance of this technique for chromatographic analysis and its maturity. The monolithic (continuous bed) stationary phases primarily synthesized as chromatographic media for biocompound separations are regarded as the fourth generation of biochromatographic stationary phases. Monoliths (continuous beds) are widely used in the HPLC and capillary format separations. They are also used in the chip format separations. Compatibility of the technique with the capillary format separations gained particular interest of the researchers and companies developing chromatographic columns for micro and nanoseparations (column I.D. >150 µm and I.D.<150 µm respectively). Three most important reasons can be mentioned. First is the simplicity of “packing” of the capillary, which is accomplished by drawing the solution of the continuous bed precursors into capillary using vacuum or moderate pressure and simultaneous synthesis of the stationary phase in situ. Second reason is no need of the supporting frits, installation of which in the particulate capillary column technologies requires certain experience and often causes problems of permeability or mechanical strength or bubble formation operating in CEC. [...]Biochemijos katedraVytauto Didžiojo universiteta

Ištisiniai sorbentai (monolitai): nejudrios fazės skysčių chromatografijai, gautos naudojant hidrofobine sąveika pagrįstą fazių atsiskyrimo mechanizmą

The pioneering research work published by Hjertén et al. [J. Chromatogr. 473 (1989) 273] in 1989 dealing with development and application of the continuous bed (monolithic) technique as an attractive alternative for the classical packed columns in chromatography, stimulated further investigations in this direction. The research data published since that time on the development and application of the continuous beds formed using hydrophobic interaction-based phase separation mechanism are reviewed. Some innovative species of the beds, such as polyrotaxane beds or nonparticulate restricted-access materials for direct analysis of the biological fluids in the capillary format are also discussed. Characteristic features and practical details of the continuous bed technique are revealed. Due to many advantages, the continuous bed technique became a competitor with the traditional packings in capillary or chip-based microanalysis. The importance of the continuous bed morphology on the chromatographic characteristics is shown. The applicability of modern microscopic analysis to evaluate the morphology of the continuous beds is demonstratedVytauto Didžiojo universiteta

Application of microanalytical methods for investigation of biological objects

Cheminės analizės instrumentiniai metodai yra vienas svarbiausių įrankių biologinių objektų tyrimams atlikti. Instrumentine analize yra pagrįsti genomo ir pogenominiai (proteomo, metabolomo ir kt.) tyrimai. Pastarąjį dešimtmetį vykta sparti instrumentinės analizės metodų miniatiūrizacija. Miniatiūrizacijos pagrindiniai tikslai yra sparti, naši, efektyvi, didelės skiriamosios gebos, taupi ir aplinką tausojanti analizė. Vytauto Didžiojo universiteto chemijos katedra specializuojasi modernių mikroanalizės metodų vystyme ir jų taikyme biologinių objektų tyrimui. Jau keli metai aktyviai bendradarbiaujama su VDU Kauno botanikos sodo bei Kauno Medicinos universiteto Farmacijos fakulteto mokslininkais atliekant vaistinių augalų cheminę analizę. Tam naudojami kapiliarinės elektroforezės, efektyviosios skysčių chromatografijos, dujų chromatografijos metodai. Bandiniai ruošiami naudojant superkritinio CO2 ekstrakciją bei kietafazę mikroekstrakciją. Su Lietuvos sodininkystės ir daržininkystės institutu bendradarbiaujama atliekant augalų epigenetinius tyrimus. Pranešime bus pateiktos modernių mikroanalizės metodų vystymo gairėsInstrumental methods of chemical analysis are one of the major tools for investigation of biological substances. Investigation of genome, metabolome, proteome are based on these methods. A trend of analytical methods miniaturization is observed within the last decade. The main task of miniaturization of analysis is high speed, high efficiency, high resolution, inexpensive and environmentally friendly methods. The Department of Chemistry of the Vytautas Magnus University is involved in development of microanalytical methods and their application for analysis of biological objects. Phytochemical analysis of medicinal plants is carried out in extensive collaboration with VMU Kaunas Botanical Garden and the Faculty of Farmacy of Kaunas University of Medicine. Capillary electrophoresis, gas chromatography and high performance liquid chromatography are used for analysis of plants. For preparation of samples supercritical fluid extraction and solid phase microextraction are used. Epigenetic investigation of plants is carried out in cooperation with Lithuanian Institute of Horticulture. In this report the overview of modern microanalysis methods will be presentedVytauto Didžiojo universiteta

Quantitative and qualitative determination of honey phenolic compounds

Biochemijos katedraVytauto Didžiojo universiteta

The evaluation of monolothic (continous bed) acrylamide based adsorbents for nanochromatography by inverse size exlusion chromatographic porosimetry : comparison of two evaluation methodologies

Vytauto Didžiojo universiteta

Evaluation of ethyl alcohol denaturant denatonium benzoate by capillary liquid chromatography with acrylamide based continuos bed

Šiame straipsnyje aptariamas kapiliarinės skysčių chromatografijos (KSC) su ištisiniu (monolitiniu) polimeriniu sorbentu metodas bitrekso analizei. Ištirti aštuoni etilo alkoholio bandiniai, kuriuose buvo nustatyta bitrekso koncentracija. Taip pat nustatyta ir palyginta bitrekso koncentracija viršutinėje bei apatinėje indo su alkoholiu dalyje. Po 24 h laikymo viršutiniame sluoksnyje bitrekso koncentracija tampa mažesnė nei bendra jo koncentracija (sumaišytame) bandinyje. Apatiniame sluoksnyje bitrekso koncentracija laikant parą laiko gali padidėti iki dviejų ir daugiau kartų. Įvertinta denatonio benzoato aptikimo riba sudarė 0,17 mg/l, o nustatymo riba – 0,29 mg/l. Nustatytas bitrekso nustatymo linijinis intervalas KSC metodu etilo alkoholyje buvo nuo 0,17 mg/l iki 36,6 mg/l. Ištirti keturių prekių mėginiai, kuriuose vienas iš komponentų yra denatūruotas alkoholisDenatonium benzoate was discovered by Macfarlan Smith in 1958. Later it was used as a denaturant in ethyl alcohol. Evaluation of denatonium benzoate (bitrex) concentration in the denatured ethyl alcohol and different products is of high importance. Bitrex concentration in ethyl alcohol, according to Lithuanian list of denaturants, has to be from 3 to 20 mg/L. Generally HPLC is used for the analysis of denatonium benzoate in denatured alcohol, in some cases CE is applied. In one HPLC application, the silica based continuous bed RP-18e (Merck, Germany) was used as a stationary phase of analytical column. Neither capillary chromatography nor acrylamide based continuous bed was used for the analysis of denatonium benzoate. For the first time we applied capillary liquid chromatography and acrylamide based continuous bed for the evaluation of denatonium benzoate in denatured alcohol. Eight samples of denatured alcohol were analyzed. Concentration of bitrex was evaluated at the top and bottom of the storage vessel and compared to average concentration of extensively mixed primary sample. It was found that bitrex concentration in these layers is different. After storage for 24 hours in the top layer bitrex concentration is lower than average bitrex concentration in the mixed sample and at the bottom bitrex concentration can be twice and more times higher than the average concentration. The limits of detection of the method was 0.17 mg/l and limit of quantification 0.29 mg/l. Good linearity was obtained for the concentration range 0.17 mg/l - 36.6 mg/l. Four samples of the products, where one of the components was denatured alcohol, were analyzedVytauto Didžiojo universiteta

Synthesis of reversed phase continuous bed (monolith): optimization of efficiency and hydrophobicity

The main advantages of synthesis of polymeric continuous bed are: 1) in situ polymerization; 2) no need of frits is required and 3) morphology of continuous bed is formed during polymerization. Because morphology is formed during polymerization, parameters governing phase separation and morphology have to be strictly controlled. During polymerization of continuous beds with porogens usually is controlled: total monomer concentration and total crosslinker concentration, porogen type and composition, polymerization temperature and time etc [1]. In case of water based polymerization media, during polymerization is controlled: total monomer concentration and total crosslinker concentration, polymerization media concentration (ionic strength), type and pH, polymerization temperature and time etc [2, 3]. [...]Biochemijos katedraVytauto Didžiojo universiteta

Evaluation of total amount of phenolic compounds, flavonoids and antioxidant activity in medical functional teas by means of spectrophotometric methods

In recent years there has been increasing interest worldwide in the use of alternative - herbal medicine and this shows, that the tea is the most popular drug form produced from medicinal herbs. The raw material of medicinal teas were provided by from "Švencioniu vaistažolės", which is one of 4 producers currently existing in Lithuania. Preparations of herbal origin are generally used in treatment of digestive, respiratory tract, and nervous system problems. For analysis was taken these compositions of medicinal herbs: 1) Species expectorales cum liquiritiae radices; 2) Species cholagoga; 3) Species diaphoretica; 4) Species cholametabolica ; 5) Species sedative; 6) Species pectorals; 7) Species antihaemorrhoidales; [...]. These species of medicinal herbs contain various bioflavonoids and phenolic compounds, which are widely used for prevention and treatment of various illnesses. It is known that the mixtures of medicinal herbs have a complex influence on the human organism and the rational combination of medicinal herbs can improve their curative action and decrease the undesirable side effects. [...]Vytauto Didžiojo universiteta