Photochemical transformation of zearalenone in aqueous solutions under simulated solar irradiation: Kinetics and influence of water constituents.

The presence of estrogenic mycotoxins, such as zearalenone (ZEN), in surface waters is an emerging environmental issue. Little is known about its phototransformation behavior, which may influence its environmental fate. In this context, the phototransformation of ZEN was investigated in pure water, river water and estuarine water using simulated sunlight irradiation. Kinetic studies revealed that two concomitant processes contribute to the fate of ZEN under solar irradiation: photoisomerization and photodegradation. This phototransformation followed a pseudo-first order kinetics. ZEN degrades quickly in natural waters and slowly in deionized water, with half-lives (t1/2) of 28 ± 4 min (estuarine water), 136 ± 21 min (river water) and 1777 ± 412 min (deionized water). The effects of different water constituents on the phototransformation of ZEN in aqueous solution have been assessed (NaCl, Ca2+, Mg2+, Fe3+, NO3- and oxalate ions, synthetic seawater, Fe(III)-oxalate and Mg(II)-oxalate complexes, humic acids, fulvic acids and XAD-4 fraction). In the presence of synthetic seawater salt (t1/2 = 18 ± 5 min) and Fe(III)-oxalate complexes (t1/2 = 61 ± 9 min), the transformation rate increased considerably in relation to other water constituents tested. The solution pH also had a considerable effect in the kinetics with maximum transformation rates occurring around pH 8.5. These results allow us to conclude that phototransformation by solar radiation can be an important degradation pathway of ZEN in natural waters.

Contamination of cachaça by PAHs from storage containers.

Cachaça is a distiled beverage obtained from the fermentation of sugar cane syrup that, depending on the production procedures, may be susceptible to contamination by polycyclic aromatic hydrocarbons (PAHs). These compounds present carcinogenic and/or mutagenic properties and offer a risk to human health. Sixteen PAHs were determined in cachaças that had been stored in glass bottles and in polyethylene tank by gas chromatography coupled with mass spectrometry. The quantification of the PAHs utilised an internal standard. The limits of detection and quantification varied from 0.05 to 0.10µgL(-)(1) and 0.20 to 0.30µgL(-)(1), respectively. A total PAH concentration of 51.57µgL(-)(1) was found in the beverages that were stored in the tank, while the concentration in the cachaça stored in glass jugs was 6.07µgL(-)(1). These results indicate that the polyethylene tank is a source for PAHs in cachaça.

Distribution and sources of aliphatic hydrocarbons in surface sediments of Sergipe River estuarine system.

The assessment of aliphatic hydrocarbons was performed in the Sergipe River estuarine system, northeastern Brazil. Aliphatic hydrocarbons concentration ranged from 9.9 ug g⁻¹ up to 30.8 ug g⁻¹ of dry sediment. The carbon preference index (CPI, based on nC24 to nC34 range), indicated predominance of petrogenic input in two of the sites analyzed (P4 and P5). The unresolved complex mixture (UCM) was found to be present in seven of the nine sites sampled (except for P4 and P5). Overall, the results of this work suggest that there is a mix of organic matter sources to the sediment. Although the coast of Sergipe has an intense off shore petroleum exploration and the Sergipe River crosses the entire city of Aracaju, the capital city of Sergipe, non-significant anthropogenic fingerprint was assessed.

New catalytic ultrasound method for derivatization of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid in urine, with analysis by GC-MS/MS.

A new procedure is described for the derivatization by silylation of 11-nor-Δ(9)-tetrahydrocannabinol-9-carboxylic acid (THCCOOH) present in urine, followed by analysis using gas chromatography-tandem mass spectrometry. A conventional procedure for derivatization of the analyte was evaluated using two types of experimental design. A 2(3) factorial design considered the parameters temperature, reaction time, and the solvent/derivatization agent ratio. A central composite design (CCD) was applied to optimize the values of the significant variables. The optimum conditions were a reaction temperature of 50 °C, a reaction time of 30 min, and a BSTFA/acetone ratio of 40:20. The use of imidazole as a catalyst, together with ultrasonication, reduced the reaction time to 5 min and increased the efficiency of derivatization of THCCOOH, compared with the conventional method. The operating conditions of the tandem mass spectrometer were also optimized. The method was linear in the concentration range 1-50 ng mL(-1) (R(2) = 0.9951). Intra- and inter-day precisions were 7.7-12.3% and 11.1-13.9%, respectively, recoveries ranged between 91 ± 8% and 101 ± 12%, accuracy (as % bias) was between -11.7% and +0.7%, and limits of detection and quantification were 0.5 and 1.0 ng mL(-1), respectively.