卷 73, 编号 6 (2018)

A technique of extracting cotinine in urine and wastewaters, followed by its quantitative determination, using high performance liquid chromatography combined with tandem mass-spectrometric detection is presented. The method is characterized by low detection limits and high levels of efficiency and sensitivity. The optimal conditions for the solid-phase extraction of cotinine from urine and wastewaters are found. This technique makes it possible to reliably estimate the content of cotinine in the urine of active and passive smokers and in wastewaters.

The influence of the lead content in the K₂O–PbO–SiO₂ system on the color of glass caused by the plasmon resonance of gold nanoparticles is discussed. It is shown that in glass with a high lead content a longer time of secondary heat treatment (striking) and high temperature affect the hypsochromic shift of the plasmon frequency in UV-vis spectra, while for the remaining compositions, a bathochromic effect is observed. This is explained by the change in the structural role of the lead in the silicate matrix.

Enzymes that hydrolyze the quorum-sensing signal molecules of pathogenic bacteria allow us to influence the number and stability of their populations. The combination of such enzymes with antibiotics can be considered as one of the ways of solving the problem of regulation of the development of antibiotic resistance. In the presence of puromycin and ceftiofur (0.2 g/L) during exposure at 25–41°C, the stabilization of His₆-OPH lactonase activity is observed. The molecular docking of antibiotics to the surface of the His₆- OPH dimer reveals the antibiotics binding both to the area near the active sites of the enzyme subunits and to the region of contact between the subunits of the dimer, which possibly led to the stabilization of the enzyme. The presence of enzyme preparations facilitates the reduction on 36–48% of the minimum inhibitory concentration (MIC) of puromycin and ceftiofur on the growth of highly concentrated (10⁶ cells/mL) cell populations of Pseudomonas aeruginosa B-6643 and Escherichia coli B-6645.

The use of the achievements attained in colloid chemistry and other fields of chemical sciences allows us to develop new nanoscale systems for chemosensorics. Mixed monolayers consisting of a new chemosensory amphiphilic dithia-18-crown-6, which contains a dye of 4-alkylpyridine series with polyvinyl stearate at the water–air interface, are obtained and studied. The influence of various concentrations of silver ions on these mixed monolayers is studied. A promising method for the detection of silver ions in water using the given nanoscale systems based on chemosensory amphiphilic dithia-18-crown-6 is proposed.