New chemiluminescent method of levofloxacin and ofloxacin determination based on terbium (III)-sensitized fluoroquinolone-KBrO3 reaction.

Fluoroquinolones can be oxidized with some agents, in this study selected fluoroquinolones (levofloxacin, ofloxacin, ciprofloxacin, norfloxacin, pefloxacin and enrofloxacin) were oxidized with potassium bromate in the presence of terbium (III) ions. According to the kinetic and spectral analysis of chemiluminescence emitted by the above systems, the terbium (III) ions were the only emitter. The excitation of the lanthanide ion was a result of the process of energy transfer from the products of fluoroquinolones oxidation to Tb(III) ions. The highest intensity of chemiluminescence was obtained for levofloxacin and ofloxacin containing an alkoxy substituent at C-8 in the quinoline ring. The chemiluminescence intensity was correlated linearly (r = 0.9994) with the concentration of ofloxacin (or levofloxacin) in the range 1 × 10-6 to 4 × 10-5 mol L-1 ; the detection limit was 3 × 10-7 mol L-1 for both fluoroquinolones. In the optimized conditions, the chemiluminescence of the levofloxacin (or ofloxacin)-Tb(III)-KBrO3 -H2 SO4 systems was used to determine these compounds in a mixture of fluoroquinolones and in pharmaceuticals.

High Voltage Electrochemiluminescence (ECL) as a New Method for Detection of PAH During Screening for PAH-Degrading Microbial Consortia.

The search for new bacterial consortia capable of removing PAH from the environment is associated with the need to employ novel, simple, and economically efficient detection methods. A fluorimetric method (FL) as well as high voltage electrochemiluminescence (ECL) on a modified surface of an aluminum electrode were used in order to determine the changes in the concentrations of PAH in the studied aqueous solutions. The ECL signal (the spectrum and emission intensity for a given wavelength) was determined with the use of an apparatus operating in single photon counting mode. The dependency of ECL and FL intensity on the concentration of naphthalene, phenanthrene, and pyrene was linear in the studied concentration range. The biodegradation kinetics of the particular PAH compounds was determined on the basis of the obtained spectroscopic determinations. It has been established that the half-life of naphthalene, phenanthrene, and pyrene at initial concentrations of 50 mg/l (beyond the solubility limit) reached 41, 75, and 130 h, accordingly. Additionally, the possibility of using ECL for rapid determination of the soluble fraction of PAH directly in the aqueous medium has been confirmed. Metagenomic analysis of the gene encoding 16S rRNA was conducted on the basis of V4 hypervariable region of the 16S rRNA gene and allowed to identify 198 species of bacteria that create the S4consortium. The consortium was dominated by Gammaproteobacteria (78.82 %), Flavobacteria (9.25 %), Betaproteobacteria (7.68 %), Sphingobacteria (3.76 %), Alphaproteobacteria (0.42 %), Clostridia (0.04 %), and Bacilli (0.03 %).

Spectroscopic study of DHDA complex formation of d- and f-electron metal ions in methanol solution.

Synthesis and spectral characterization of N,N'-Bis(2,4-dihydroxobenzylidene)1,2-diaminobenzene (DHDA) complexes with chosen f- and d-metal ions are described. Physico-chemical properties of a series of complexes: DHDA-La(NO(3))(3), DHDA-Eu(NO(3))(3). DHDA-Yb(NO(3))(3), DHDA-Cu(NO(3))(2), DHDA-Zn(NO(3))(2), DHDA-Co(NO(3))(2), were studied in methanol solution using UV-VIS, IR and fluorescence spectroscopy. Based on the absorption spectra the conditional stability constants of the metal complexes were determined.