Development of a new analytical method for online simultaneous qualitative determination of aluminium (free aluminium ion, aluminium-fluoride complexes) by HPLC-FAAS

The paper presents a novel method for simultaneous online examination of inorganic forms of aluminium: AlF₂⁺, AlF^2+, and Al³⁺ by means of the high performance liquid chromatography hyphenated with a detection by the atomic absorption spectrometry with flame atomization (HPLC-FAAS) without post-column reaction. The application of optimization procedure conditions of chromatographic separation of inorganic forms of aluminium was achieved by the analytical column IonPac CS5A (Dionex) with guard column IonPac CG5A (Dionex) and an aqueous ammonium chloride mobile phase, at pH about 3 with gradient elution. The separation of Al forms with nominal charge of 1+, 2+, 3+ required a run time of less than 8 min during a single analysis. The proposed method has been successfully used for the examination of aluminium forms formation AlF_n⁽³⁻ⁿ⁾⁺ in environmental samples.     

X-ray diffractometry of γ-irradated linear polyterephthalates

The linear polyesters of terephthalic acid OCOC₆H₄COO[CH₂]_n with 2 ? n < 10 were investigated. The degree of crystallinity and dimension of crystallites were measured for both unirradiated and γ-irradiated samples. Irradiations were carried out at a dose rate of 1 · 5 Mrad/hr; doses varied from 50 to 3000 Mrad. Polymers were irradiated in the presence of air or after prolonged degassing at 10⁻⁵mm Hg.     

An EPR study of γ-irradiated single crystals of cholesta-4, 6-diene-3-one

Cholesta-4, 6-diene-3-one single crystals irradiated with γ-rays at room temperature have been investigated by electron spin resonance. EPR spectra at room temperature exhibit a characteristics triplet which splits into two doublets. The main triplet has been interpreted as being caused by the addition of a hydrogen atom to the 7-position of the molecule, leaving an unpaired electron in the 2p₂ orbital of the carbon atoms in position 6 and 4. The hyperfine spectrum is generated by interaction of the unpaired electron with two equivalent -protons in position 4 and 6 and with tow non-equivalent β-protons in position 7. The principal values of the hydrogen hyperfine tensors are determined together with the g tensor of this radical.     

Antioxidant,Anti-Inflammatory,and Anti-Diabetic Activity of Phenolic Acids Fractions Obtained from Aerva lanata (L.) Juss.

Many plants that are commonly used in folk medicine have multidirectional biological properties confirmed by scientific research. One of them is Aerva lanata (L.) Juss. (F. Amaranthaceae). It is widely used, but there are very few scientific data about its chemical composition and pharmacological activity. The aim of the present study was to investigate the chemical composition of phenolic acid (PA)-rich fractions isolated from methanolic extracts of A. lanata (L.) Juss. herb using the liquid/liquid extraction method and their potential antioxidant, anti-inflammatory, and anti-diabetic properties. The free PA fraction (FA), the PA fraction (FB) released after acid hydrolysis, and the PA fraction (FC) obtained after alkaline hydrolysis were analysed using liquid chromatography/electrospray ionization triple quadrupole mass spectrometry (LC-ESI-MS/MS). The phenolic profile of each sample showed a high concentration of PAs and their presence in A. lanata (L.) Juss. herb mainly in bound states. Thirteen compounds were detected and quantified in all samples, including some PAs that had not been previously detected in this plant species. Bioactivity assays of all fractions revealed high 2,2-diphenyl-1-picrylhydrazyl (DPPH^•) (2.85 mM Trolox equivalents (TE)/g) and 2,2-azino-bis-3(ethylbenzthiazoline-6-sulphonic acid) (ABTS^•+) (2.88 mM TE/g) scavenging activity. Fraction FB definitely exhibited not only the highest antiradical activity but also the strongest xanthine oxidase (XO) (EC₅₀ = 1.77 mg/mL) and lipoxygenase (LOX)(EC₅₀ = 1.88 mg/mL) inhibitory potential. The fraction had the best anti-diabetic properties, i.e., mild inhibition of α-amylase (EC₅₀ = 7.46 mg/mL) and strong inhibition of α-glucosidase (EC₅₀ = 0.30 mg/mL). The activities of all analysed samples were strongly related to the presence of PA compounds and the total PA content.     

Enzymatic detection of glucose using fluoride-selective electrodes with polymeric membranes

The feasibility of using polymeric membrane fluoride-selective electrodes based on zirconium(IV) 5,10,15,20-tetraphenylporphyrin as a detector in a flow-injection analysis (FIA) system for glucose determination was examined. The optimization of enzymatic reactions, FIA system configuration and enzyme-immobilization process was performed. It was shown that the resulting flow-injection system exhibits good working parameters, such as reproducibility, linear range of glucose concentration (3 × 10⁻³–10⁻¹ M), sampling rate (60 samples per minute) and lifetime (over 1 month). The performance of the polymeric membrane electrode was similar to that of a crystalline LaF₃ electrode. The results of glucose determination in synthetic samples with the proposed system show good agreement with real glucose concentrations.     

ICP slurry introduction for simple and rapid determination of Pb, Mg and Ca in plant roots

Pb, Mg and Ca were simultaneously determined in plant roots by slurry introduction into inductively coupled plasma optical emission spectrometry (SS-ICP-OES). Slurries were prepared in 0.5% or 5% (v/v) HNO₃ with 0.5, or 5% (v/v) Triton X-100. Omission of the Triton X-100 improved results. Compared with wet ashing of the root sample followed by ICP-OES, ICP-MS and FAAS, the method offers: comparable results, simplification of sample preparation, less sample contamination, and reduction in the use of dangerous and corrosive reagents. The precisions varied: 1.7% for Mg, 2.8% for Ca and 4.3% for Pb, and were not significantly different (95% confidence level) from those of conventional analysis.      

Determination of chemical shift parameters from zeeman nuclear quadrupole resonance in single crystals

The components of the chemical shift tensor of the ³⁵Cl nuclei in paradichlorobenzene single crystal have been determined directly from Zeeman-split NQR spectra, with the magnetic field applied parallel to the principal axes of the electric-field-gradient tensor. The results are compared with values obtained by NMR in the pure quadrupole regime.     

The use of microwave radiation for obtaining carbonaceous adsorbents from biomass and their use in elimination of inorganic pollutants

A new technology of obtaining activated carbons by physical and direct activation of biomass with the use of microwave radiation is described. The effect of activation temperature (700 and 800 °C) and two periods of time (15 and 30 min) on the textural parameters, acid–base character of the surface and sorption properties of activated carbons was tested. The resulting carbons were characterized by low-temperature nitrogen sorption and determination of pH as well as the number of surface oxygen groups. The sorption properties of the activated carbons obtained were characterized by determination of nitrogen dioxide and hydrogen sulphide adsorption in dry and wet conditions as well as by iodine removal from aqueous solution. The final products were adsorbents of surface area ranging from 291 to 368 m²/g and pore volume from 0.20 to 0.26 cm³/g, showing basic character of the surface. The results obtained in our study have proved that suitable choice of the pyrolysis and activation procedure for hay with the use of microwave radiation permit producing adsorbents with good capacity toward toxic gases of acidic character as well as inorganic pollutants of molecules of size similar to that of iodine molecules.     

Towards More Photostable,Brighter, and Less Phototoxic Chromophores: Synthesis and Properties of Porphyrins Functionalized with Cyclooctatetraene

Free base and zinc porphyrins functionalized with cyclooctatetraene (COT), a molecule known as a good triplet-state quencher, have been obtained and characterized in detail by structural, spectral, and photophysical techniques. Substitution with COT leads to a dramatic decrease of the intrinsic lifetime of the porphyrin triplet. As a result, photostability in oxygen-free solution increases by two to three orders of magnitude. In non-degassed solutions, improvement of photostability is about tenfold for zinc porphyrins, but the free bases become less photostable. Similar quantum yields of photodegradation in free base and zinc porphyrins containing the COT moiety indicate a common mechanism of photochemical decomposition. The new porphyrins are expected to be much less phototoxic, since the quantum yield of singlet oxygen formation strongly decreases because of the shorter triplet lifetime. The reduction of triplet lifetime should also enhance the brightness and reduce blinking in porphyrin chromophores emitting in single-molecule regime, since the duration of dark OFF states will be shorter.