Comparison of the contents of various antioxidants of sea buckthorn berries using CE

The increased interest in sea buckthorn (Hippophae rhamnoides L.) made it possible to investigate the antioxidant content in it. To address this issue, the presence of following antioxidant compounds were analyzed: trans-resveratrol, catechin, myricetin, quercetin, p-coumaric acid, caffeic acid, L-ascorbic acid (AA), and gallic acid (linear range of 50-150 micromol/L) in six different varieties of sea buckthorn berries extracts (sea buckthorn varieties: "Trofimovskaja (TR)," "Podarok Sadu (PS)," and "Avgustinka (AV),") received from two local Estonian companies. Trans-Resveratrol, catechin, AA, myricetin, and quercetin were found in extracts of sea buckthorn. Moreover, AA, myricetin, and quercetin contents were quantified. The biggest average AA content was found in TR (740 mg/100 g of dried berries, respectively). Furthermore, the same varieties gave the biggest quercetin content 116 mg/100 g of dried berries, respectively. For analysis, CZE was used and the results were partly validated by HPLC. Statistically no big differences in levels of antioxidants were consistently found in different varieties of sea buckthorn extracts investigated in this work.     

Systematic synthesis of phthalimide-protected unsaturated hydrazine heterocycles

A four-step route for the synthesis of novel phthalimide-protected hydrazine heterocycles that include a C?C double bond in the cycle was developed. Phthalimide-protected Boc-hydrazine was used as a starting material, which was alkylated with bromoalkenes in mild conditions. Further steps involved Boc-deprotection and second alkylation with bromoalkenes. Finally, the heterocycles were produced by ring-closing metathesis. This route allows access to these versatile building blocks without using electrophilic amination or nitrosylation, therefore, significantly reducing environmental and safety concerns. Phthalimide-protected heterocycles can be derivatized further by modifying the carbon–carbon double bond and by deprotection and subsequent functionalization of the primary amino group. During the current research, various five- to seven-membered hydrazine heterocycles and numerous novel intermediate compounds were synthesized and thoroughly characterized.     

Electrowetting on dielectric actuation of droplets with capillary electrophoretic zones for MALDI mass spectrometric analysis

An automated fraction collection interface was developed for coupling CE with MALDI-MS. This fraction collection approach is based on the electrowetting on dielectric (EWOD) phenomenon performed on a digital microfluidic (DMF) board; it does not rely on a MALDI spotter. In this study, a four-peptide mixture was used as a sample test, and the separations were conducted in a portable CE instrument with a 150 μm o.d. × 50 μm i.d. capillary and a contactless conductivity detector. The CE instrument was interfaced with a robust DMF board. The CE fractions were directly deposited onto the DMF board at predetermined locations prior to MALDI analysis. The series of experiments determined the lowest concentration that produces a measurable MALDI signal. The concentrations were 0.25, 0.5, 0.05, and 0.05 nmol for bradykinin, angiotensin, ACTH (18-39), and insulin, respectively. The contactless conductivity detector limit of detection for the same analytes was 2.5 μmol.     

Capillary Electrophoresis as a Monitoring Tool for Flow Composition Determination

Flow analysis is the science of performing quantitative analytical chemistry in flowing streams. Because of its efficiency and speed of analysis, capillary electrophoresis (CE) is a prospective method for the monitoring of a flow composition withdrawn from various processes (e.g., occurring in bioreactors, fermentations, enzymatic assays, and microdialysis samples). However, interfacing CE to a various flow of interest requires further study. In this paper, several ingenious approaches on interfacing flow from various chemical or bioprocesses to a capillary electrophoresis instrument are reviewed. Most of these interfaces can be described as computer-controlled autosamplers. Even though most of the described interfaces waste too many samples, many interesting and important applications of the devices are reported. However, the lack of commercially available devices prevents the wide application of CE for flow analysis. On the contrary, this fact opens up a potential avenue for future research in the field of flow sampling by CE.     

Interactions of Pb2+ with fulvic acid by electrophoretically mediated on-capillary microanalysis

Studies of yessotoxin involving confirmation of fragmentation processes using a high-resolution orthogonal hybrid quadrupole time-of-flight (QqTOF) mass spectrometer and nanoLC hybrid quadrupole TOF MS have been undertaken. The fragmentation of YTX was studied in negative mode using nano electrospray (nanoESI) QqTOF mass spectrometry. Three major molecule-related ions were observed, [M - 2Na + H]-, [M - Na]- and [M - 2Na]2-, and fragmentation of the latter was studied in detail. This showed that product ions were formed as a consequence of charge-remote fragmentation processes that included a strong directional cleavage of the polyether rings of YTX. NanoLC coupled with QqTOF MS was used to determine YTX in small samples of the phytoplankton, Protoceratium reticulatum, by monitoring the [M - 2Na]2- ion at m/z 570. A PepMap C18 nanoLC column (75 microm x 10 cm, 100 A, 3 microm, LC Packings) was used and the solvent was acetonitrile/water (90:10 (v/v)) containing 1 mM ammonium acetate, at a flow rate of 400 nl/min, for 30 min. Calibrations obtained with YTX standard solutions were linear over four orders of magnitude, 0.75-250 ng/ml; r2 = 0.9947-0.9998. Phytoplankton cells (ca. 100-300) were picked, extracted with methanol/water (40:60), and the YTX concentration was determined over the range 0.011-0.020 ng/cell. The detection limit (3 x S/N) of this method was ca. 0.5 pg YTX on-column.     

Micellar electrophoresis using ionic liquids

In this study, ionic liquid based cationic surfactants were evaluated as pseudo-stationary phases in micellar electrokinetic chromatography (MEKC). The aggregation behaviour of long-chain (C(12) and C(14)) alkylimidazolium ionic liquids in water and aqueous phosphate buffer was investigated by spectrophotometry. The critical micelle concentrations of these salts were determined and compared to those of tetradecyl- and dodecyltrimethylammonium chloride, salts commonly used in capillary electrophoresis. The practical utilization of a new type of surfactant in MEKC was evaluated by introducing an ionic liquid into the running aqueous buffer to separate neutral analytes-methylresorcinol isomers and benzene derivatives.     

Analysis of the stable free radical scavenging capability of artificial polyphenol mixtures and plant extracts by capillary electrophoresis and liquid chromatography–diode array detection–tandem mass spectrometry

The oxidation process of phenolic compounds of an artificial mixture consisting of six polyphenols and the extract of eggplant (Solanum melongena) skin was monitored by using capillary zone electrophoresis and liquid chromatography–diode array detection–tandem mass spectrometry. The methods developed enabled simultaneous evaluation of the antioxidative capability of each compound. The above oxidation process was carried out using two radicals, viz. the 2,2-diphenyl-1-picrylhydrazyl and hydroxyl radicals generated via the Fenton reaction. The radical scavenging effects of artificial and natural polyphenol mixtures were compared.     

Application of the Peak Fitting Programme “Galactic” For FTIR-Analysis of OH-Ions in Natural and Synthetic Apatites

Abstract

Most of the studies on heavy metals binding ability of apatites have been carried out on hydroxyapatites (HA_P) [Ca_l0(PO₄)₆(OH)₂]. As the chemical characteristics of apatite depend substantially on the substitutions in its structure, the apatites with F substitution for OH and CO₃ ²for PO₄ ³ were studied.     

Capillary electrophoresis with LED-induced native fluorescence detection for determination of isoquinoline alkaloids and their cytotoxicity in extracts of Chelidonium majus L

In this study, we introduced a simple and sensitive method of capillary electrophoresis with ultraviolet light-emitting diode-induced native fluorescence (UV-LEDIF) detection for the determination of isoquinoline alkaloids in extracts of Chelidonium majus L. Samples were extracted with acidic methanol and the extracts were directly analysed by CE. Simultaneous determination of protopine, chelidonine, coptisine, sanguinarine, allocryptopine, chelerythrine and stylopine was performed in 20mM phosphate buffer (pH 3.1). The baseline separation of these alkaloids was finished within 20 min. As these alkaloids have native fluorescence, they were directly detected using the commercially available UV light emitting diode without troublesome fluorescent derivatisation. Satisfactory LOD values were obtained for the studied compounds considering their appearance in natural extracts. Lower limits of detection were 0.05 μg/mL for protopine, 0.06 μg/mL for stylopine and allocryptopine, 0.07 μg/mL for chelidonine, 0.22 μg/mL for sanguinarine, 1.7 μg/mL for chelerythrine and 5.5 μg/mL for coptisine. The developed method was successfully applied to determine the contents of seven alkaloids in the aerial parts of Chelidonium majus L, which varied from 0.025 to 0.763% (w/w). Also, to demonstrate the potential of the proposed CE method, an estimation of the cytotoxic properties of selected Celandine alkaloids in a natural extract was carried out.