RESUMO
BACKGROUND: Environmental pollutants are known to be ubiquitous and may present toxic effects (endocrine-disruption properties, carcinogenicity ) and represent a real threat to human health. The aim of the present pilot study was to assess the content of environmental pollutants (inorganic, persistent, and non-persistent pollutants) in biological samples (urine, serum, and whole blood), collected from volunteers in Kinshasa, capital of Democratic Republic of Congo, in order to identify pollutants of interest and to design a protocol for a larger scale study. METHODS: From randomly selected 15 volunteers living in Kinshasa, aged from 25 to 66 years, (mean age = 43.4 years), including 10 men and 5 women, urine, whole blood, and serum samples were used in this study to estimate the contents in these environmental pollutants, using inductively coupled plasma mass spectrometry, gas chromatography coupled to mass spectrometry, and liquid chromatography coupled to mass spectrometry. RESULTS: When compared to data nationally and internationally available, the preliminary outcomes of this study indicated a very high level of exposure to environmental pollutants in the population of Kinshasa, especially for heavy metals, parabens and triclosan. To a lesser extent, contamination measured for glyphosate, phthalates, organochlorine pesticides, pyrethroids and dialkylphosphate pesticides was also significant. In contrast, the investigated population of Kinshasa was found to be weakly exposed to other persistent organic pollutants like polychlorinated biphenyls, brominated flame retardants, phenolic organohalogens, and perfluoroalkyl substances. CONCLUSION: Although the biologic fluids were collected from a limited number of volunteers (n = 15), the results of the present report clearly indicate that the population of Kinshasa is not spared by the investigated environmental pollutants. Moreover, this study gives us important information to design a larger scale study protocol.
RESUMO
A silver-based solid carbon paste electrode was developed for use as a detector in ion chromatography (IC) for the sensitive determination of iodide in real samples. Micro- and nano-particles of silver were investigated for the fabrication of different electrodes. The iodide assay was based on IC with amperometric detection (IC-AD) at a silver composite electrode polarized at +0.080 V versus Ag/AgCl. Free iodide and organoiodide compounds were studied. The detection process was characterized by studying the redox behavior of iodide ions at both silver and silver composite electrodes by cyclic voltammetry (CV). The presence of iodide ions in solution was found to considerably facilitate metallic silver oxidation, with response currents directly related to iodide concentration. The calibration curve at the selected silver carbon paste electrode was linear in the concentration range comprised between 0.635 microg/L and 63.5 microg/L iodide. The relative standard deviation (R.S.D.) for successive injections was below 3% for all iodide standard solutions investigated. The limit of detection (LOD) was 0.47 microg/L (3.7 nmol/L) for an injection volume of 20 microL, i.e. 74 fmol injected. The IC-AD method was successfully applied to the determination of iodide in complex real samples such as table salts, sea products and iodide bound drug compounds. The analytical accuracy was verified by the assay of iodide in milk powder from an iodide certified reference material (CRM) Community Bureau of Reference (BCR) 150.