Headspace gas chromatographic determination of β-caryophyllene in Epilobium angustifolium L. extracts

Epilobium angustifolium L. is a plant widely used in folk medicine. It is rich in biologically active compounds including phenols, flavonoids, terpenes, aliphatic acids and sterols; however, until now, little attention has been paid to its volatile components. This research demonstrated that Epilobium angustifolium L. is rich in β-caryophyllene that is possibly responsible for its unique therapeutic properties. The leaves of Epilobium angustifolium L. are traditionally used as a tea. On the other hand, β-caryophyllene is soluble in oils, thus an extract of Epilobium angustifolium L. in edible oils should also demonstrate a healing effect. Therefore, quick and reliable methods of β-caryophyllene determination in edible oils and in water solutions are required. In this work, headspace gas chromatography is suggested to determine β-caryophyllene. At the optimized chromatographic conditions for β-caryophyllene solutions in coconut oil the calibration curve was linear up to 10 mg g–1, the detection limit was 60 µg kg–1, for β-caryophyllene solutions in water the calibration curve was linear up to 40 µg l–1, and the detection limit was 6 µg l–1. The methods were applied for the β-caryophyllene determination in the extract of Epilobium angustifolium L. in sunflower oil and in Epilobium angustifolium L. tea.

Design and applications of a neural networks assisted portable liquid surface tensiometer

In this paper, a portable instrument for surface tension measurements, characterization and applications is described. The instrumentation is operated wirelessly, and samples can be measured in situ. The instrument has changeable different size probes; therefore, it is possible to measure samples from 1 ml up to 10 ml. The response of the measured retraction force and the concentrations of measured surfactant is complex. Therefore, two calibration methods were proposed: (i) the conditional calibration using polynomial and logarithmic fitting and (ii) the neural network trained model prediction of the surfactant concentration in samples. Calibrating the instrument, the neural network trained model showed a superior coefficient of determination (0.999), comparing it to the conditional calibration using polynomial (0.992) and logarithmic (0.991) fit equations.

Home-made cider brandy (Calvados): analysis of distillation fractions by gas chromatography-mass spectrometry method

In this study, the distillation fractions of cider brandy produced illegally in Lithuania using gas chromatographic-mass spectrometry method were investigated. The conditions of gas chromatography-mass spectrometry were firstly optimized. A qualitative analysis of three distillation fractions was performed and estimated. The first fraction (initial) of distillation products was collected for 0.5 h, the second one (intermediate) was collected for the next 1.5 h and the third (main) fraction for the next 5 h. A method of the quantitative analysis of different volatile analytes such as acetaldehyde, methanol, ethanol, 1-propanol, isobutanol, 1-butanol, isoamyl alcohol and benzyl alcohol in the distillation products was also developed. The concentration of ethanol decreased significantly in the main fraction in comparison with those of the initial and intermediate fractions. The concentration of 1-propanol, isobutanol, 1-butanol and isoamyl alcohol in the last fraction decreased drastically as well.

Characterization of natural silicate garnets by means of non-destructive testing methods

Two kinds of natural silicate garnets from the known origin countries were investigated: pyralspites – pyrope (Russia), almandine (India), rhodolite (India), spessartine (India), blue colour-change garnet (Sri Lanka), and ugrandites – andradite (Russia), demantoid (Russia), topazolite (Russia), rainbow garnet (Japan), grossular (Kenya-Tanzania), colourless grossular (India), light orange grossular (India), dark green tsavorite (Tanzania), medium green tsavorite (Kenya), light green tsavorite (Kenya), orange hessonite (Sri Lanka), pink hessonite (Sri Lanka), cinnamon hessonite (India) and uvarovite (Russia). The chemical composition of the garnets was performed with a scanning electron microscope. The physical properties such as specific gravity and refractive index were measured for the majority of garnets investigated. The spectroscopic meth­ods – visible light absorption spectrophotometry, Raman spectroscopy and cathodoluminiscence microscopy – were applied for the characterization of the mentioned natural silicate garnets.

Cirsium vulgare leaves: isolation and identification of phenolic compounds

There are a few new researches on the pharmaceutical and nutraceutical application of Cirsium vulgare, but they do not reflect the full potential use of this plant. For the best of our knowledge, no study has been conducted so far to determine the impact of extraction methods and conditions on the extraction yields of phenolic compounds from Cirsium vulgare. We aimed to investigate a simple and sensitive HPLC-PDA method to determine phenolic compounds in Cirsium vulgare extracts. Three extraction techniques as maceration (ME), ultrasound-assisted extraction (UAE) and heat-reflux extraction (HRE) were applied and compared for sample preparation to obtain a high recovery of the phenolic compounds. The developed HPLC-PDA method can be used for the preparations of extracts with a high content of bioactive compounds for both pharmaceutical and nutraceutical applications. Moreover, it was validated and used for the qualitative and quantitative evaluation of phenolic compounds. A simple extraction procedure for phenolic compounds from Cirsium vulgare leaves was optimized in this work through the use of the heatreflux extraction method with 50% ethanol and extraction time of 1.5 h.

Aqueous dispersions of epoxy oligomers: Stability and rheological properties

In this study, the stability of the aqueous dispersions of epoxy oligomers was investigated. The following epoxy oligomers with various numbers of epoxy groups were used for the characterization: NPEL 127, NPEL 128, NPEL 134, NPPN 631, EPOXY 520 and DEG-1. A non-ionic surfactant Emulsogen LCN-287 based on alkyl polyethylene glycol ether was used as an emulsifier. The dispersions of epoxy resins were fabricated by changing the content of a non-ionic surfactant (emulsifier) in a range from 2 to 6 wt.%. It was demonstrated that the stability of aqueous emulsions depends not only on the type of resin, but also on the content of the oil phase and the concentration of the emulsifier. The rheological properties of the aqueous dispersions of epoxy oligomers were investigated as well.

Porous poly(urethane urea) microparticles for immobilization of maltogenic α amylase from Bacillus stearothermophilus

Maltogenic α amylase from Bacillus stearothermophilus (BsMa) was immobilized by covalent attachment and physical adsorption onto porous poly(urethane urea) (PUU) microparticles obtained from poly(vinyl alcohol) (PVA) and 4,4’-methylenebis(cyclohexyl diisocyanate) (H12DI) by onepot synthesis. The influence of PUU synthesis parameters such as PVA and H12DI molar ratio, synthesis time and temperature on porosity, surface area, structure of microparticles and catalytic activity and stability of immobilized BsMa was investigated. The highest efficiency of the immobilization of BsMa onto the PUU carrier was 97% and the highest residual stability of the immobilized enzyme reached 95% after 28 days of storage at 4°C. The optimal activity temperature of immobilized BsMa was at 80°C and it was higher than that of native enzyme. Effects of ionic strength and repetitive batch processing cycles on the activity of immobilized BsMa were also studied. Immobilization of BsMa onto PUU carriers has a great potential for biotechnology and food industries.

Development of the simultaneous analysis of choline salicylate, lidocaine hydrochloride and preservatives in a new dental gel by HPLC method

A new high-performance liquid chromatography (HPLC) method for the simultaneous quantitative determination of active pharmaceutical substances and preservatives in a new dental medication has been developed. The optimization of HPLC method parameters was done through studies of a mobile phase composition and a detection wavelength. Our developing method uses an ACE C18 column (250 × 4.6 mm, 5 µm) and a gradient mode for separation with the acetonitrile and phosphate buffer solution (adjusted to pH 3.0) as mobile phases. The flow rate is 1 ml/ min, and the detection was set at 260 nm (DAD). The method was evaluated according to the ICH guidelines and the State Pharmacopoeia of Ukraine in terms of specificity, accuracy, linearity and precision (repeatability and intermediate precision). The limit of detection and the limit of quantification were also calculated. The developed method was put in place for the analysis of a combined dental gel to a quantitative determination of the APIs (choline salicylate, lidocaine hydrochloride) and preservatives (methylparaben, propylparaben).

Investigation of upconversion phenomenon in Y1-xLn3+x(BTC)(DMF)2(H2O) and Y0.8-xYb0.2Ln3+x(BTC)(DMF)2(H2O) metal organic frameworks

In this study, Y1-xLn3+x(BTC)(DMF)2(H2O) and Y0.8-xYb0.2Ln3+x(BTC)(DMF)2(H2O) metal organic frameworks (MOFs), which structure included lanthanide ions, Ln3+ (Er3+, Ho3+, Tm3+, Yb3+, Nd3+), suitable for monitoring the upconversion phenomenon, have been synthesised. For this purpose the precursor of the organic moiety, benzene-1,3,5-tricarboxylic acid (BTC), as one of the simplest and very frequently cited carboxylic acid analogues in MOF syntheses, has been selected. By characterising upconversion properties of new MOFs it was determined that only Er3+ can be used as an activator for one centre luminescence upconversion by a ground state absorption/ excited-state absorption (GSA/ESA) mechanism, while with Yb3+, Ho3+, Tm3+ and Nd3+ ions the upconversion was not observed. It was also established that BTC cannot initiate triplet–triplet annihilation upconversion (TTA-UC) as this mechanism sensitizer. Yb3+–Er3+ and Yb3+–Ho3+ ion pairs as a sensitizeractivator were suitable for two-centre luminescence upconversion by a GSA/ excited-state upconversion (GSA/ESU) mechanism. A pair of Yb3+–Tm3+, contrary as shown in the literature review, does not exhibit upconversion properties in the synthesised MOFs.

Silver-coated monolitic silica column for separation of benzo[a]pyrene from petroleum

Monolithic silica solid-phase extraction column has been successfully applied for the rapid fractionation and subsequent gas chromatographic analysis of benzo[a]pyrene from the diesel and oil matrix. Due to π-π electronic interactions between silver nanoparticles on the sorbent surface and aromatic analyte specific retention was achieved. It was demonstrated that only 0.2 g of the sorbent and 6 ml of the organic solvent are enough for such separation.