Sergio Zappoli

Inorganic, organic and macromolecular components of fine aerosol in different areas of Europe in relation to their water solubility

A chemical mass balance of fine aerosol (<1.5 μm AED) collected at three European sites was performed with reference to the water solubility of the different aerosol classes of components. The sampling sites are characterised by different pollution conditions and aerosol loading in the air. Aspvreten is a background site in central Sweden, K-puszta is a rural site in the Great Hungarian Plain and San Pietro Capofiume is located in the polluted Po Valley, northern Italy. The average fine aerosol mass concentration was 5.9 μg m-3 at the background site Aspvreten, 24 μg m-3 at the rural K-puszta and 38 μg m-3 at the polluted site San Pietro Capofiume. However, a similarly high soluble fraction of the aerosol (65–75%) was measured at the three sites, while the percentage of water soluble organic species with respect to the total soluble mass was much higher at the background site (ca. 50%) than at the other two sites (ca. 25%). A very high fraction (over 70%) of organic compounds in the aerosol consisted of polar species. The presence of water soluble macromolecular compounds was revealed in the samples from K-puszta and San Pietro Capofiume. At both sites these species accounted for between ca. 20–50% of the water soluble organic fraction. The origin of the compounds was tentatively attributed to biomass combustion.

Study of humic-like substances in fog and interstitial aerosol by size-exclusion chromatography and capillary electrophoresis

Abstract Recently, there have been implications that the bulk of the organic carbon in the atmospheric aerosol and fog is contained in an “air polymer” whose chemical nature is poorly understood. Since several properties (e.g. acidity, UV–VIS absorbance, fluorescence) of this polymer were found to be very similar to those of humic substances the term humic-like substances (HULIS) was proposed. In this work size-exclusion chromatography and capillary electrophoresis are used to obtain new information about some properties of the HULIS found in fog water and aqueous extract of interstitial aerosol. Retention and migration behaviour as well as mass spectra are investigated and compared to those of reference humic substances. The capillary electrophoresis is applied for the determination of the range of protonation constants of the HULIS, as well. Scavenging ratio for the HULIS is calculated and found to be about the same as those of ammonium and sulphate. The results imply that such compounds may play a role in cloud condensation.

Polychlorinated biphenyl degradation activities and hybridization analyses of fifteen aerobic strains isolated from a PCB-contaminated site.

Fifteen bacterial strains using biphenyl as sole carbon and energy source, obtained from different positions and depths of a polychlorinated biphenyl (PCB)-contaminated area, were analyzed for their basic metabolic phenotypes and subjected to genomic DNA hybridization screening for the presence of well characterized bph operons such as those of Pseudomonas pseudoalcaligenes KF707 and Rhodococcus globerulus P6. Most of the isolates belonged to the gamma-subdivision (Pseudomonas stutzeri, P. plutida, P. fluorescens and Vibrio logei species) and to the beta-subdivision (genera Alcaligenes, Comamonas, Ralstonia) of the Proteobacteria. All the isolates were able to cometabolize different low chlorinated PCB congeners. Among the dichlorinated biphenyls tested, a lower degradation capacity was observed for the di-ortho substituted congeners, whereas high levels of degradation were observed for the di-meta and di-para isomers, whether they were chlorinated on one or on both rings. The PCB congeners nonsubstituted in the 2,3 or 2,3 and 3,4 positions were also degraded by most of the isolated strains, which were, however, unable to significantly metabolize PCBs with more than 3 chlorine atoms. Five of the isolated strains were also able to degrade some of the tri- and tetrachlorobiphenyls tested. Southern hybridization analysis showed a strong homology between four of the fifteen isolated strains and the bph operon obtained from P. pseudoalcaligenes strain KF707. Conversely, none of the isolates here examined showed homology with the bph operon of R. globerulus strain P6. In line with this, the KF707 bph probe strongly hybridized with DNA of a significant number of bacterial colonies obtained from selected locations in the contaminated area using biphenyl-supplemented minimal medium agar plates.

The presence and distribution of heavy metals in municipal solid waste incinerators

Heavy metals are both a hazard to human health and a risk to the environment. Among the different sources, it seems interesting to study the waste incineration process for the increasing number of composite materials which are disposed by this method. This paper will focus mainly on the processing of heavy metals in municipal solid waste (MSW) incineration plants. In particular, the study will be concerned with analyzing, on the basis of established methodologies, the amount and type of heavy metals in both input waste and each incineration effluent. The data from this kind of analysis is essential for optimizing as much as possible incinerator working conditions and for being able to correctly choose the most appropriate effluent treatment technique.

Electrocatalytic oxidation of salicylic acid by a cobalt hydrotalcite-like compound modified Pt electrode

In this paper a study of the electrocatalytic oxidation of salicylic acid (SA) at a Pt electrode coated with a Co/Al hydrotalcite-like compound (Co/Al HTLC coated-Pt) film is presented. The voltammetric behaviour of the modified electrode in 0.1M NaOH shows two different redox couples: Co(II)/Co(III) and Co(III)/Co(IV). The electrocatalysis occurs at the same potential of the latter couple, showing that Co(IV) centers act as the oxidant. The CV investigation demonstrates that the process is controlled both by mass and charge transfer and that the Co(IV) centers involved in the oxidation are two for each SA molecule. The estimated value of the catalytic constant is 4×10(4) M(-1) s(-1). The determination of salicylic acid was performed both by DPV and chronoamperometry. The linearity ranges and the LOD values resulted 1×10(-5) to 5×10(-4), 5×10(-7) to 1×10(-4), 6×10(-6) and 2×10(-7) M, respectively. The Co/Al HTLC electrode has been used for SA determination in BAYER Aspirina® and the obtained results are consistent with an independent HPLC analysis.

A new approach for the fractionation of water-soluble organic carbon in atmospheric aerosols and cloud drops

A novel approach is described for the fractionation of water-soluble organic carbon (WSOC) in atmospheric aerosols and cloud drops. The method is based on the preliminary adsorption of the sample, acidified at pH 2, on a polymeric styrene-divinylbenzene resin (XAD-2) and subsequent elution with a series of solvents, which leads to the fractionation of the sample into three classes of compounds. The method was set up using synthetic mixtures of organic compounds and then applied to selected samples of atmospheric aerosols and cloud drops. All samples and collected fractions were analysed using size exclusion chromatography (SEC). This method proved particularly useful both in providing information on the organic content of the samples and for the characterisation of the macromolecular compounds (MMCs) in the samples. Synthetic samples were prepared using humic, fulvic and tannic acid to simulate naturally occurring MMCs. In the first fraction, eluted with HCl, only the most soluble organic compounds (oxalic acid, formic acid and acetic acid) were collected. In the second fraction, eluted with methanol, the major part of the organic material was collected together with the more hydrophilic constituents of the humic substances. In the third fraction, it was possible to separately recover the more hydrophobic component of the humic substances. A large number of atmospheric samples (fog, aerosol, cloud) were then analysed using SEC. Most of these samples evidenced a noteworthy chromatogram at 254 nm. Moreover, the chromatographic area evidenced a clear linear correlation with the total organic carbon (TOC) values. The fractionation method on XAD-2 was finally applied to selected atmospheric samples, yielding three classes of organic compounds. In each sample, a non-negligible amount of compounds with dimensional and chemical properties similar to humic substances were collected in the third fraction. The carbon content in this latter fraction was estimated both by TOC and by means of the correlation between TOC and SEC area.

Biodegradation of chlorinated biphenyls (Fenclor 42) in batch cultures with mixed and pure aerobic cultures

Abstract Two consortia of bacterial strains belonging to the genus Pseudomonas , and a pure strain of Pseudomonas cepacia were isolated from river sediments by using biphenyl and 4- chlorobiphenyl as a sole carbon source. Metabolic degradation of various polychlorinated biphenyls (PCBs) by these organisms was studied. The biodegradation products of 4-chlorobiphenyl were analyzed in Pseudomonas . Several low chlorine PCB congeners of Fenclor 42 mixture can be easily degraded by these mixed and pure cultures, especially in growing cell systems. Chlorine was not produced during the degradation of all the chlorobiphenyls tested, including 4-chlorobiphenyl.

ANALYTICAL PROFILING OF SELECTED ANTIOXIDANTS AND TOTAL ANTIOXIDANT CAPACITY OF GOJI (LYCIUM SPP.) BERRIES

&NA; Goji berries and derived products represent a relevant source of micronutrients, most of which are natural antioxidants and contribute to the high nutritional quality of these fruits. Three brands of dried goji berries have been analysed by a multidisciplinary approach to get an insight into both their content of selected antioxidants and their antioxidant capacity (AC). The former goal has been achieved by developing a liquid chromatographic method coupled to mass spectrometry and combined to a fast solid phase extraction. Several significant representative antioxidant compounds belonging to the following classes: flavonoids, flavan‐3‐ols, phenolic acids, amino acids and derivatives, and carotenoids have been taken into account. Quercetin and rutin were found to be the predominant flavonoids, chlorogenic acid was the most abundant phenolic acid and zeaxanthin was the major carotenoid. The AC of the goji berries has been evaluated by four analytical methods in order to estimate the contributions of different reactions involved in radicals scavenging. In particular, AC has been determined using 3 standardised methods (DPPH, ABTS, ORAC) and a recently proposed electrochemical method, which measures the scavenging activity of antioxidants towards OH radicals generated both by hydrogen peroxide photolysis and the Fenton reaction. The results obtained from chemical composition and antioxidant capacity assays confirm the high nutritional and commercial value of goji berries and highlight that the three brands do not exhibit significant differences. Graphical abstract Figure. No caption available. HighlightsThe nutritional features of goji berries were assessed.An original SPE‐LC–MS/MS method was developed and validated to determine 23 antioxidants.Goji berries antioxidant activity was tested by using multiple antioxidant assay strategies.Modified electrochemical sensor detecting radicals by degradation of a polyphenol film deposited on a glassy carbon electrode was implemented.A relationship between antioxidant capacity and content of antioxidants has been investigated.

Application of ion interaction chromatography to the determination of metal ions in natural water samples

Abstract The retention behaviour of Fe(III), Cu, Pb, Zn, Ni, Co, and Mn in ion interaction chromatography was investigated to optimise metal ion separation and detection in water samples. A solution of an alkanesulfonate, the ion interaction reagent (IIR), tartaric acid, and acetonitrile (or methanol) was used as eluent. Retention times were found to be accelerated by increasing the following: organic modifier concentration, tartaric acid concentration, and the pH of the eluent solution. In contrast, increasing the length of the IIR carbon chain was found effective in enhancing the retention times of metal ions. An analytical method for the determination of metals at the μg/1 level was developed and applied to the analysis of natural water samples.

Dye-coated stationary-phases: A retention model for anions in ion-interaction chromatography

SummaryThe separation of inorganic anions (NO3−, NO2−, Cl−, Br−, I−, SO42−, S2O32−) by ion-interaction chromatography mediated with a specific dye has been investigated. Chromatography was performed on a LiChrospher RP-18 colum dynamically coated with crystal violet, using acetonitrile-water buffered with phthalate as the mobile phase. The presence of the dye in the eluent enabled indirect spectrophotometric detection of the analytes, which have no significant UV absorption. Retention data were collected for the different anions by varying the composition of the mobile phase according to a full factorial experimental design. A theoretical model for the retention of singly- and doubly-charged analytes, on the basis of the two main processes of ion-exchange and ion-pair formation, has been proposed and validated with the experimental data.