Presence of antibiotic resistance genes and its association with antibiotic occurrence in Dilúvio River in southern Brazil.

It is known that antibiotics are widely used in human and veterinary medicine. In some countries the use is controlled, however few restrictions to their use are enforced in many countries. Antibiotics and their metabolites can reach the water bodies through sewage systems, especially in those countries with partial or absent wastewater treatment systems. The overuse and misuse of antibiotics has been linked with the increase of antibiotic resistant bacteria. The relation between the occurrence of antibiotics and resistance genes in surface waters has been widely studied worldwide evincing the great importance of this subject. In this work, a methodology for quantification of 40 antibiotics of 5 different classes, in river water, by SPE-LC-MS/MS was validated. Samples were taken during a two-year period from Dilúvio River, a stream that crosses the city of Porto Alegre (RS - Brazil) and receives in nature domestic effluent. The methodology met the requirements of validation, with Limit of Quantification varying from 20 ng L-1 to 100 ng L-1. A total of 48 samples was analyzed for the presence of antibiotics for two years. From the 40 antibiotics analyzed, 8 of them (Azithromycin, Cephalexin, ciprofloxacin, clindamycin, norfloxacin, sulfadiazine, sulfamethoxazole and trimethoprim) were present in all sampling points in the range of

The optimization of biohydrogen production by bacteria using residual glycerol from biodiesel synthesis.

In this research the production of hydrogen by Klebsiella pneumoniae BLb01 using residual glycerol discharged from a biodiesel fuel production plant was investigated. Klebsiella pneumoniae BLb01 was isolated from a bacteria-rich sludge of an upflow anaerobic sludge blanket reactor (UASB) of a soybean processing plant. A Plackett-Burman design (P-B) and Response Surface Methodology (RSM) were employed to determine the optimal condition for enhanced hydrogen production. The maximal hydrogen production, which was 45.0 mol % and with 98% of glycerol degradation, was achieved with the optimized medium with the following composition: 30 g L(-1) glycerol; 3 g L(-1) yeast ex tract 3 g L(-1) K(2)HPO(4); 1 g L(-1) KH(2)PO(4); temperature 39°C and pH 9.0. These results show the ability of this new strain of effectively converting residual glycerol into value-added energy products.

Lipid biomarkers profile--presence of coprostanol: recent sediments from Rodrigo de Freitas Lagoon-Rio de Janeiro, Brazil.

Coprostanol (contribution characteristic from anthropogenic pollution) and other lipid biomarkers (sterols, fatty alcohols and fatty acids) were identified and quantified in recent sediment extracts from Rodrigo de Freitas Lagoon, a touristy spot of Rio de Janeiro-Brazil, using gas chromatography with mass selective detector (GC-MSD). The determination of lipid biomarkers profile indicates an autochthonous biogenic contribution due to the presence of phytoplankton, zooplankton, bacteria and dinoflagellates. The allochthonous biogenic contribution was confirmed by detection of biomarkers from higher plants in the sediments due to the influence of the Atlantic Forest inserted in the studied region. The concentration of the studied compounds varied from 5.53 to 216.47 microg.g(-1) for sterols, 0.47 to 5.35 microg.g(-1) for fatty alcohols, 20.15 to 66.22 microg.g(-1) for fatty acids and 0.08 to 3.98 microg.g(-1) for coprostanol. The presence of coprostanol was attributed to illegal untreated sewage discharge in the pluvial collector which ends up in the Lagoon.

p-Nitro-N-propylaniline/silica: synthesis, characterization, and its application in matrix solid phase dispersion for multiresidue analysis of pesticides in carrots.

A new material for matrix solid phase dispersion (MSPD) was synthesized -- p-nitro-N-propylaniline/silica (pNNPASi) by grafting reactions, characterized by elemental analysis and N(2)-adsorption-desorption isotherms, and tested for multiclass multiresidue analysis of pesticides in wet and freeze-dried carrots. Results obtained applying this new solid phase sorbent to MSPD extraction of ten pesticides (trichlorphon, trifluralin, dicloran, chlorothalonil, prometryn, linuron, captan, procymidone, prochloraz, and deltametrin) in wet carrots showed better results than the ones obtained for freeze-dried samples. Recoveries were in the range of 48-106% and precisions varied from 6 to 20% when wet samples were employed. Comparison between pNNPASi sorbent and C(18) showed better performance of pNNPASi for eight out of ten pesticides tested. The LOQs show that the developed method can be used to detect the pesticides investigated in carrots at concentrations below the maximum residue levels (MRL) established by EU, USEPA, and National Sanitary Surveillance Agency (ANVISA). Linuron, captan, prochloraz, and deltamethrin were found in at least one of the two commercial samples studied in concentrations above the LOQ of this method. Concentrations of the last three pesticides were above the European MRL in one of the commercial samples.

Quantitative analysis of benzene, toluene, and xylenes in urine by means of headspace solid-phase microextraction.

A simple method for benzene, toluene, and xylenes (BTX) quantitative analyses in human urine was developed, using headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled to mass spectrometry detection in the single ion monitoring mode. The developed method is solventless, non-invasive, requires small volume of sample (1 ml), shows high selectivity, sensitivity, repeatability, and linearity (correlation coefficients >0.998), providing a useful alternative to assess human exposure to BTX compounds due to occupational reasons or eventual exposure to organic solvents. Detection limit varies from 0.28 to 0.5 ppb (v/v).