Effects of redox conditions on the control of arsenic mobility in shallow alluvial aquifers on the Venetian Plain (Italy).

The Venetian Plain is known for the occurrence of areas with high concentrations of arsenic in groundwater (greater than 400 µg/L). The study area represents the typical residential, industrial and agricultural features of most Western countries and is devoid of hydrothermal, volcanic or anthropogenic sources of arsenic. The aim of the study is to model the arsenic mobilization and the water-rock interaction by a complete hydrogeochemical investigation (analyses of filtered and unfiltered groundwater sediment mineralogy and geochemistry). The groundwater arsenic contamination and redox conditions are highly variable. Groundwaters with oxidizing and strongly reducing potentials have much lower arsenic concentrations than do mildly reducing waters. The grain size of the aquifer sediments includes gravels, sands and silty-clays. A continuous range of organic material concentrations is observed (from zero to 40%). The amount of sedimentary organic matter is highly correlated with the arsenic content of the sediments (up to 300 mg/kg), whereas no relationships are detectable between arsenic and other chemical parameters. The occurrence of arsenic minerals was observed as a peculiar feature under the scanning electron microscope. Arsenic and sulfur are the sole constituents of small tufts or thin crystals concentrated in small masses. These arsenic minerals were clearly observed in the peat sediments, in agreement with the geochemical modeling that requires very reducing conditions for their precipitation from the groundwater. The modeling suggests that, under oxidizing conditions, arsenic is adsorbed; moreover, a continuous decrease in the redox potential causes increasing desorption of arsenic. If the reducing conditions become more intense, the formation of As-S minerals would explain the lower concentration of arsenic measured in the strongly reducing groundwater. Even if As-sulfides are rare under low-temperature conditions, the anomalous abundance of reductants (organic matter) can locally stabilize As-S minerals, which can scavenge large quantities of groundwater arsenic.

X-ray microdiffraction and urine: a new analysis method of crystalluria.

The qualitative and quantitative analyses of crystalluria have clinical significance in the diagnosis and prognosis of urolithiasis. The aim of this paper is to provide a new accurate methodology to get qualitative and quantitative data on urine particulate in patients with renal stone disease.The procedure involves a urine collection, the separation of the solid residual by centrifugation, and its analysis by X-ray diffraction, utilizing a micro-diffractometer in order to analyze very low amounts of residual. The spectrum obtained was converted into 2 θ -I profiles and quantitatively refined by Rietveld method. The proposed methodology has the advantage to accurately quantify all crystalline phases and the amorphous component of the urine; anyway urine samples have to be centrifuged and analysed as soon as possible, because the quantitative results obtained by the X-ray microdiffraction showed that after some days and at room temperature urine increased significantly both amorphous and crystalline phases.

Validation data for HPLC/FLD determinations of ochratoxin A in red paprika and black pepper adopting a one-step clean-up procedure.

Validation data for the determination of ochratoxin A (OTA) in two spice matrices, red paprika and black pepper, were obtained for samples prepared with a simplified single-step clean-up column. Extracts of finely ground samples of red paprika and black pepper were prepared and applied to a Mycosep 229 Ochra clean-up column. The purified extract was then subjected to HPLC/FLD analysis. The relative standard deviation for repeatability (RSDr) of the method was 11.8% for red paprika and 9.9% for black pepper. The limit of detection (LOD) value (three times the noise) was estimated as corresponding to the response of an extract derived from a blank matrix (previously washed) and spiked at 1.0 microg kg(-1). The limit of quantitation (LOQ) (three times LOD) was 3.0 microg kg(-1). The performance of the one-step column clean-up procedure appears to be a suitable alternative to commonly used clean-up techniques and allows the precise determination of OTA in two complex matrices.

Identification of organic contaminants in disposable aluminium foil containers.

A series of disposable aluminium foil containers designed for cooking and packaging foods and available on the Italian market were investigated. Using different analytical techniques (near infrared (NIR), High Resolution Gas Chromatography (HRGC), gas chromatography/mass spectrometry (GC/MS)), organic substances used as lubricants in the manufacturing of the containers were detected on the aluminium layer in contact with the food. These contaminants were not mineral hydrocarbon fractions used for the shaping of can lids and bodies, but had an organic structure identifiable as esters derived by synthesis between fatty acids C8 and C10 with glycerine, and between C16 and C18 with butyl alcohol. Mixtures of higher esters were also identified as contaminants. Twelve samples were analysed, and the total amount of contaminant substances was found to range from 900 to 1200 microg dm-2. It is recommended, for safety and compliance with European Community (EC) Regulation No. 1935/2004 (27 October 2004), that the use of aluminium foil containers be subject to appropriate regulation concerning substances adopted for technological purposes.

Chapter 11.6 Clays and Clay Minerals as Drugs.

This chapter discusses the applications of clays and clay materials as drugs. Clay minerals are efficient against several aggressors that cause major disorders of the gut. These beneficial effects of clay minerals (on the gastrointestinal mucosa) are associated with two mechanisms of action: (1) adsorption of the aggressors or their toxic secretions and (2) modification of the thickness and rheological properties of the adherent mucus, reinforcing the natural defenses of the gastrointestinal mucosa. At the surface of the gut, a mucus gel adheres to the epithelial cells of the mucosa. This adherent mucus is dynamic, being continuously secreted by the calceiform cells and regularly eroded by environmental aggressors present in the gut lumen. The mucus gel is largely composed of glycoprotein polymers, lipids, and proteins linked together by covalent bonds. It acts as a physical barrier protecting the mucosa against penetration by extraneous molecules and mechanical injury. By maintaining a pH gradient and competing with the epithelial surface for microorganisms, the mucus gel also acts as a chemical barrier.

Fast determination of Sudan I by HPLC/APCI-MS in hot chilli, spices, and oven-baked foods.

The Commission Decision of EC dated 20 June 2003, on emergency measures concerning hot chilli and hot chilli products coming into any EC member state, required that the consignments of such products should be accompanied by an analytical report showing that they are free of artificial dye Sudan I. The opportunity to set a confirmatory method is evident, and the paper proposes a HPLC/APCI-MS method useful for identification and quantitation of Sudan I, also at very low levels in hot chilli, other spices, and oven-baked foods. Validation data are reported.

A simplified method for the HPLC resolution of alpha-carotene and beta-carotene (trans and cis) isomers.

A new HPLC/DAD (Diode Array Detector) method is proposed for the identification of some carotene isomers. The operating conditions adopted permit the resolution of alpha-carotene, all-trans-beta-carotene, 9-cis-beta-carotene, 13-cis-beta-carotene and 15-cis-beta-carotene. Moreover, the chromatographic conditions reported are simplified in respect of those reported up to now. The method is applied to the determination of carotenoids in a dried Dunaliella salina extract, but it could be also applied to other organic matrices such as eggs.

Carotenoids reduce the chromosomal damage induced by bleomycin in human cultured lymphocytes.

The supplementation with beta-carotene and canthaxanthin, two carotenoids with and without pro-vitamin A activity, reduced in vitro the number of micronuclei induced in human cultured lymphocytes by the chemotherapeutic radiomimetic drug bleomycin. The genotoxic activity of this substance is supposed to be mediated by a free radical mechanism. The reduction of micronucleated cells was in correlation with donors' carotenoid blood levels. It has been observed that 20 weeks are needed, following the end of carotenoid supplementation, in order to return to the high levels of micronuclei induced by bleomycin. It is suggested that this protective effect is due to the antioxidant properties of carotenoids acting against free radical-mediated genotoxic damage.

Calcium oxalate smear layer: mineralogical and crystallographic study.

Different methods to reduce dentine hypersensitivity have been tested by means of oxalate treatments. Natural material (20 teeth) and commercial oxalates have been employed. As a result the dentinal tubules are filled by small crystals preventing dental disease. Permeability measurements have been performed in order to quantify results. The composition of the synthetic smear layer produced after oxalate treatment have been investigated by powder diffraction method suggesting calcium oxalate formation.

Reduction of chromosomal damage by bleomycin in lymphocytes from subjects supplemented with carotenoids. Relevance in bleomycin tumour chemotherapy. Preliminary results.

In a one year-study, 9 healthy human donors were being supplemented with beta-carotene (BC) plus canthaxanthin (CX), to determine the effect of carotenoids on chromosomal damage (micronuclei) induced in the donors' lymphocyte cell cultures by exposure to bleomycin (BLM), an antineoplastic drug that has been shown to produce chromosomal aberrations through the production of free radicals. The first four months monitoring data, including determination of carotenoid blood levels, are here reported. These data show that carotenoid supplementation significantly decrease (up to 50%) the formation of micronuclei induced by BLM in human lymphocyte cell cultures. This decrease is in correlation with carotenoid blood levels.

Effects of propolis flavonoids on virus infectivity and replication.

The effect of five propolis flavonoids on the infectivity and replication of some herpesvirus, adenovirus, coronavirus and rotavirus strains has been studied. Experiments were performed in vitro in cell cultures using the viral plaque reduction technique. The cytotoxicity of flavonoids, including chrysine, kaempferol, acacetin, galangin and quercetin, was evaluated on uninfected monolayers to determine their effect on cell growth and viability. Chrysine and kaempferol caused a concentration-dependent reduction of intracellular replication of herpes-virus strains when monolayers were infected and subsequently cultured in a drug-containing medium. However, virus infectivity was not significantly affected. Acacetin and galangin had no effect on either the infectivity or replication of any of the viruses studied. Quercetin reduced infectivity and intracellular replication, but only at the highest concentrations tested.