Analytical Methodologies for the Assessment of Phthalate Exposure in Humans.

Screening and quantification of phthalate metabolites in biological matrices provide information on the phthalate exposure. The preferred tool for the determination of phthalate metabolites is liquid chromatography-mass spectrometry, typically preceded by a sample extraction step. Method development for the determination of phthalate metabolites by hyphenated techniques faces challenges due to the widespread occurrence of phthalates in the laboratory and sample collection materials that impairs their accurate quantification. Here, the analytical methods that have been developed for the determination of biomarkers of phthalates in various matrices are presented, and limitations and challenges in these applications are discussed.

Laboratory and field dissipation of penoxsulam, tricyclazole and profoxydim in rice paddy systems.

Rice cultivation relies on pesticide applications to ensure high yields. However, the regular use of pesticides seriously affects the quality of neighboring surface water systems. Thus complete knowledge of the environmental fate and dissipation of pesticides in the paddy rice environment should become available. So far only a few studies have provided comprehensive assessment of the dissipation of pesticides under the submerged cultivation conditions followed in rice. Thus, laboratory and 2-year field studies were performed to assess the dissipation of two new generation rice herbicides (penoxsulam and profoxydim) and one of the most important rice fungicides (tricyclazole). A good agreement between laboratory and field experiments was observed with a faster dissipation of penoxsulam and tricyclazole under field conditions. Profoxydim was the least persistent chemical (DT50 soil<1d; DT50 water 0.5-1.2d), followed by penoxsulam which persisted for longer particularly in the water compartment (DT50water=3.8-5.9d). Tricyclazole was the most persistent pesticide, especially in the soil compartment with DT50 values of 44.5-84.6 (field) and 197d (laboratory). These results could be utilized for the assessment of the environmental risk associated with the use of those pesticides in rice cultivation and the determination of potential mitigation measures for minimizing the risk for contamination of neighboring natural water resources.

Voltammetric study of interaction between polymers (PEI and TMO) and pDNA on a hanging mercury drop electrode.

Electrochemical DNA biosensors can become a powerful tool for the investigation of potent changes on the plasmid DNA structure caused by polymers used as non-viral vectors in gene delivery. Trimethylated chitosan oligomer (TMO) and polyethylenimine (PEI), offering biocompatibility, low immunogenicity and minimal cytotoxicity, are being studied as model non-viral carriers. The information obtained is intended to serve as a basis for developing a new analytical system for the study of the effect of any physically or chemically synthesized polymer on DNA structure.

Carbonaceous species of TSP in urban and rural sites around coal-fired power stations in northwestern Greece.

Total suspended particles from urban and rural locations around an industrial complex with four coal-fired power stations were collected for a period of 6 months (January-June 2001). Mass concentrations of TSP and carbonaceous species (TC, EC, OC and BC) were determined for seven sampling sites of the studied area. The contribution of TC mass to the total particle mass was similar for all sites with an average value of 12.36+/-1.27%. The fraction of elemental carbon (EC) was estimated between 32 and 46% of the total carbon (TC). The relationship between organic and elemental carbon showed the primary origin of organic carbon (direct emissions). The OC/BC ratio values were also considered in order to get information about the enrichment of aerosols in organic carbon. Four conditional categories out of the sampling site 'collection were additionally extracted ("urban", "rural", "far" and "close" location to the power stations) and considered with respect to the values of the ratios OC/BC and OC/EC and the multiple correlation coefficients R(2) for the concentrations of OC, BC and EC. It has been found that in some cases the correlation coefficients rather than the ratios could inform on the type of site.

Study of interactions between actinomycin D and DNA on carbon paste electrode (CPE) and on the hanging mercury drop (HMDE) surface.

The interaction of actinomycin (ACTD) with double stranded (ds) calf thymus DNA and single stranded (ss) DNA was studied at the carbon paste electrode surface by means of transfer voltammetry in 0.2 M phosphate buffer solution (pH 7.4). Accordingly the interaction of actinomycin (ACTD) with ds calf thymus DNA, ss DNA and supercoiled (sc) DNA was studied using hanging mercury drop electrode in 0.3 M NaCl, and 50 mM sodium phosphate buffer (pH 8.5). The different electrochemical behaviours are presented and compared in the article.

Study of interactions between DNA-ethidium bromide (EB) and DNA-acridine orange (AO), in solution, using hanging mercury drop electrode (HMDE).

The interaction of ethidium bromide (EB) and acridine orange (AO) with double stranded (ds), thermally denatured (ss) and supercoiled (sc) DNA, in solution, was studied by alternating current voltammetry (AC voltammetry) at the hanging mercury drop electrode (HMDE) in 0.3 M NaCl+50 mM sodium phosphate buffer (pH 8.5). Their interaction with DNA is shown to be time dependent and completely different. The changes at peak 2 (peak at -1.20 V) of dsDNA form and the appearance of peak 3 (peak at -1.42 V) in scDNA form are presented as criteria declaring the different mechanism of interaction of EB and AO with DNA. Additionally, the appearance of a new peak at around -0.44 V as a result of DNA and AO interaction, differentiates the studied behaviors. The comparison of the electrochemical behaviors of these compounds highlights the differences in the mechanism of interaction.