Polycyclic aromatic hydrocarbons in bays of the Rio de Janeiro state coast, SE - Brazil: Effects on catfishes.

The Brazilian coast of the Rio de Janeiro State has bays of great economic, ecological and social importance. However, these ecosystems have been suffering intense anthropogenic influence, mainly due to the contamination by polycyclic aromatic hydrocarbons (PAHs) from urban-industrial activities. Moreover, PAHs are organic pollutants of high toxicity and carcinogenicity causing global concern to human and environmental health.

A novel strategy based on in-syringe dispersive liquid-liquid microextraction for the determination of nickel in chocolate samples.

In this work, a novel approach was developed to perform dispersive liquid-liquid microextraction using a rapid pressure variation to disperse the extraction solvent in an aqueous medium. A glass syringe was used to produce an environment subject to a rapid pressure difference. The element used as a model was nickel and the approach was called pressure variation in-syringe dispersive liquid-liquid microextraction (PV-IS-DLLME).

Development of a non-destructive method for determining protein nitrogen in a yellow fever vaccine by near infrared spectroscopy and multivariate calibration.

Near infrared spectroscopy (NIR) with diffuse reflectance associated to multivariate calibration has as main advantage the replacement of the physical separation of interferents by the mathematical separation of their signals, rapidly with no need for reagent consumption, chemical waste production or sample manipulation. Seeking to optimize quality control analyses, this spectroscopic analytical method was shown to be a viable alternative to the classical Kjeldahl method for the determination of protein nitrogen in yellow fever vaccine. The most suitable multivariate calibration was achieved by the partial least squares method (PLS) with multiplicative signal correction (MSC) treatment and data mean centering (MC), using a minimum number of latent variables (LV) equal to 1, with the lower value of the square root of the mean squared prediction error (0.

Multivariate technique for optimization of digestion procedure by focussed microwave system for determination of Mn, Zn and Fe in food samples using FAAS.

This article describes the development by response surface methodology (RSM) of a procedure for iron, zinc and manganese determination by flame atomic absorption spectrometry (FAAS) in food samples after digestion employing a focussed microwave system. A Doehlert matrix was used to find optimal conditions for the procedure through response surface study. Three variables (irradiation power and time and composition of oxidant solution-HNO(3)+H(2)O(2)) were regarded as factors in the optimization study.