Enantioselective separation of amino acids as biomarkers indicating life in extraterrestrial environments

Traces of prebiotic amino acids, i.e., the building blocks of proteins, are excellent biomarkers that could pro-vide evidence of extinct or extant life in extra-terrestrial environments. In particular, characterization of the enantio-meric excess of amino acids gives relevant information about the biotic or abiotic origin of molecules, because it is generally assumed that life elsewhere could be based on eitherLorDamino acids, but not both. The analytical pro-cedures used in in-situ space missions for chiral discrimina-tion of amino acids must meet severe requirements imposed by flight conditions: short analysis time, low energy con-sumption, robustness, storage for long periods under extreme conditions, high efficiency and sensitivity, automation, and remote-control operation. Such methods are based on gas chromatography, high-pressure liquid chromatography, and capillary electrophoresis, usually coupled with mass spec-trometry; of these, gas chromatography–mass spectrometry (GC–MS) is the only such combination yet used in space missions. Preliminary in-situ sample derivatization is required before GC–MS analysis to convert amino acids into volatile and thermally stable compounds. The silylation reagent most commonly used,N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide, isunsuitable for detection of homochirality, and alternative derivatization techniques have been developed that preserve the stereochemical configuration of the original compounds and are com-patible with spaceflight conditions. These include the reagent N,N-dimethylformamide dimethylacetal, which has already been used in the Rosetta mission, a mixture of alkyl chloroformate, ethanol, and pyridine, a mixture of perfluorinated anhydrides and perfluoro alcohols, and hexafluoroacetone, the first gaseous derivatizing agent. In all the space instruments, solvent extraction of or-ganic matter and chemical derivatization have been combined in a single automatic and remote-controlled procedure in a chemical reactor. Liquid-based separation systems have been used in space missions. In particular, microchip capillary electrophoresis, based on microfluidic lab-on-a-chip systems, enables high-performance chemical analysis of amino acids with low mass and volume equipment and lowpower and reagent consumption. Couplingwith laser-induced fluorescence detectors results in ultra-low limits of detection. This critical reviewdescribes applications of the on-board instruments used in the Rosetta mission to comets and in the more recent Mars exploration program, i.e., the Mars Science Laboratory and ExoMars missions

Progetto Lauree Scientifiche Chimica

Il Progetto Lauree Scientifiche è stato realizzato presso il Dipartimento di Chimica dell’Università di Ferrara nell'anno scolastico 2009-2010. Si tratta di un progetto nazionale promosso dal Ministero dell’Istruzione, dell’Università e della Ricerca con la collaborazione di Confindustria e della Conferenza nazionale dei presidi delle facoltà scientifiche. Gli obiettivi del progetto sono: • elaborare una serie di azioni per affrontare la disaffezione dei giovani nei confronti delle cosiddette “scienze dure”, Matematica, Fisica, Chimica; • incrementare il numero degli immatricolati ai corsi di laurea di matematica, chimica e fisica, mantenendo un alto standard di qualità degli studenti. Avvalendosi della positiva esperienza acquisita negli anni precedenti, si sono sviluppate 3 azioni principali: -attività di stage, -conferenze su argomenti di ricerca sviluppati al Dipartimento di Chimica, -laboratori e workshop rivolti ad insegnati e studenti delle Scuole Superiori

Gas Chromatography in Space Exploration

Gas chromatography (GC) has proved to be the best analytical technique for the in situ search for organic molecules in extraterrestrial environments since it meets the severe requirements imposed by flight conditions: short analysis time and low energy consumption, robustness, storage for long durations under extreme conditions, high in efficiency and sensitivity, automation, remote control operations. Exploration of our solar system has been fundamentally motivated by the search for chemical biomarkers for evidence of extinct or extant life. GC instruments have been successfully installed on probes of in situ space exploration: the payload also included pyr-GC/MS system composed of a pyrolyzer (pyr) device for analyzing organic compounds in atmosphere and soil at ppb concentration levels. This chapter describes three relevant applications concerning the on-board GC instruments for Cassini–Huygens mission to Titan, Rosetta to Comet P/Churyumov-Gerasimenko and to Mars space exploration program

Progetto Lauree Scientifiche per il Corso di Laurea in Chimica

IL Progetto Lauree Scientifiche è stato realizzato presso il Dipartimento di Chimica dell’Università di Ferrara nell'anno scolastico 2011-2012. Si tratta di un progetto nazionale promosso dal Ministero dell’Istruzione, dell’Università e della Ricerca con la collaborazione di Confindustria e della Conferenza nazionale dei presidi delle facoltà scientifiche. Gli obiettivi del progetto sono: • elaborare una serie di azioni per affrontare la disaffezione dei giovani nei confronti delle cosiddette “scienze dure”, Matematica, Fisica, Chimica; • incrementare il numero degli immatricolati ai corsi di laurea di matematica, chimica e fisica, mantenendo un alto standard di qualità degli studenti. Avvalendosi della positiva esperienza acquisita negli anni precedenti, si sono sviluppate 3 azioni principali: -attività di stage, -conferenze su argomenti di ricerca sviluppati al Dipartimento di Chimica, -laboratori e workshop rivolti ad insegnati e studenti delle Scuole Superiori

Synergistic and Antagonistic Effects of Aerosol Components on Its Oxidative Potential as Predictor of Particle Toxicity

Quantifying the component-specific contribution to the oxidative potential (OP) of ambient particle matter (PM) is the key information to properly representing its acute health hazards. In this study, we investigated the interactions between the major contributors to OP, i.e., transition metals and quinones, to highlight the relative effects of these species to the total OP. Several synergistic and antagonistic interactions were found that significantly change the redox properties of their binary mixtures, increasing or decreasing the values computed by a simple additive model. Such results from the standard solutions were confirmed by extending the study to atmospheric PM2.5 samples collected in winter in the Lombardia region, a hot spot for air pollution in northern Italy. This work highlights that a solid estimation of oxidative properties of ambient PM requires an interaction-based approach accounting for the interaction effects between metals and quinones

Gas Chromatography in Space ExplorationReference Module in Chemistry, Molecular Sciences and Chemical Engineering

Gas chromatography (GC) instruments have been successfully installed on the spatial probes for in situ chemical analyses of planetary atmospheres or surfaces, for searching for chemical biomarkers that could provide evidence of extinct or extant life in space. GC instruments and analytical procedures have been developed in order to meet the severe requirements imposed by flight conditions: short analysis time and low energy consumption, robustness, high efficiency and sensitivity, automation, and remote control operations. The instrument payloads include devices that provide different sample handling and pretreatment prior to GC analysis, such as pyrolysis for thermal volatilization of volatiles or solvent extraction of polar organic compounds. This article describes three recent space missions: Cassini–Huygens to Titan, Rosetta to comet 67P/Churyumov–Gerasimenko, and the Mars space exploration program. The technical data of the onboard GC instruments are given; the results provided by in situ GC analyses are discussed to give information on the chemical composition of the extraterrestrial atmospheres and soils

Review of PM Oxidative Potential Measured with Acellular Assays in Urban and Rural Sites across Italy

This work is an overview of the oxidative potential (OP) values up to date measured in Italy, with the aim to provide a picture of the spatial and seasonal variability of OP in the various geographical areas across Italy. The summarized works used the common acellular assays‐based dithiothreitol (OPDTT), ascorbic acid (OPAA), glutathione (OPGSH), and 2ʹ,7ʹ‐dichlorodfluorescein (OPDCFH) assays. The paper describes the association of OP responses with PM chemical composition, the sensitivity of various acellular OP assays to PM components and emission sources, and PM size distribution of the measured OP values. Our synthesis indicates that crustal and transition metals (e.g., Fe, Ni, Cu, Cr, Mn, Zn, and V), secondary ions and carbonaceous components (elemental carbon, EC, organic carbon, OC and water soluble carbon, WSOC) show significant correlations with OP across different urban and rural areas and size ranges. These chemical species are mainly associated with various PM sources, including residual/fuel oil combustion, traffic emissions, and secondary organic aerosol formation. Although the OP assays are sensitive to the same redox‐active species, they differ in the association with PM chemical components. The DDT assay is mainly sensitive to the organic compounds that are mostly accumulated in the fine PM fraction, i.e., tracers of burning sources, and redox active organics associated with other markers of photochemical aging. In contrast, OPAA and OPGSH were mostly responsive to metals, mainly those related to non‐exhaust traffic emissions (Cu, Zn, Cr, Fe, Ni, Mn, Sn, Cd, Pb), that are mainly accumulated in the coarse PM. Among the investigated sites, our synthesis shows larger OP values in Trentino region and the Po Valley, that may be explained by the high density of anthropogenic sources, and the orographic and meteorological characteristics, that favor the pollutants accumulation and aerosol photo‐oxidative aging

DETERMINATION OF OXIDATIVE POTENTIAL OF PARTICULATE MATTER BY SPECTROPHOTOMETRIC TECHNIQUES

Numerous studies have shown health effects related to exposure to ambient particulate matter (PM). In most studies effects were linked to PM mass concentrations whereas evidences indicate that the PM sources and constituents are more closely linked to the induction of toxic responses. The mechanisms of PM related health effects are still incompletely understood, but a hypothesis under investigation is that many of the adverse health effect may derive from oxidative stress. Oxidative stress results when the generations of reactive oxygen species (ROS), or free radicals, exceed the available antioxidant defenses. In light of these observations the oxidative potential (OP) has been proposed as a measure of the capacity of PM to oxidize target molecules, that may potentially serve as a biologically pertinent index of PM toxicity. Among the various assays developed for measuring OP, in this study two common kinetic methods were investigated: the ascorbate assay (AA) and the dithiothreithol (DTT) assay. In both cases the reactions were monitored spectrophotometrically and the methods were compared in terms of different sensitivity to the ROS generating compounds. The results from the two assays were compared using standard solutions of different chemical species such as transition metals, quinones and PAHs. DTT assay was found more sensitive to quinones - especially 9,10-phenanthrenequinone - compare to metals. On the contrary, the AA depletion was strongly influenced by transition metals - mainly copper - even if the assay is also sensitive to quinones. PAHs and oxo-PAHs tested showed only a slightly redox activity with these two assays. The investigated assays were applied to some real samples of PM collected in the Bologna area. Regarding the DTT assay, higher PM concentrations yield greater response, whilst ascorbate depletion was not correlated to the quantity of PM on the filter. The obtained results are very relevant to understand the relative importance of metals and organics towards ROS generation from ambient particles and highlight that other parameters as well as PM mass concentration should be taken into account to evaluate aerosol’s effects on human health

OPTIMIZATION OF A SPME/GC/MS METHOD FOR THE SIMULTANEOUS DETERMINATION OF PHARMACEUTICALS AND PERSONAL CARE PRODUCTS IN WATERS

Pharmaceuticals and Personal Care Products (PPCPs) constitute a broad class of emerging contaminants, belonging to the list of high production volume chemicals that are currently used for human and veterinary application (e.g.,pharmaceuticals, sunscreens, cosmetics, insect repellents, and soaps). In this work, a headspace solid phase microextraction (HS-SPME) method coupled with Gas Chromatography and MS detection (GC/MS) was optimized for the simultaneous determination of 21 target PPCPs in water samples. The analytes included fragrances, UV-filters, antiseptics, estrogens, anti-inflammatory drugs and pesticides. An on-fiber SPME derivatization, using silyl reagents, was performed for the analysis of more polar acidic compounds. An experimental design approach was applied to systematically investigate and optimize the operative parameters affecting the extraction recovery, namely: extraction temperature and time, derivatization time, desorption temperature and time. The optimum operating conditions were: extraction time of 125 min at a temperature of 40C; derivatization time of 30.5 min; desorption time of 2 min at a temperature of 300C. Under these conditions, good reproducibility was assessed as RDS% values lower than 10% for underivatized PPCPs and lower than 20% for derivatized compounds. The method detection limits were between 0.7 and 9.0 ng L-1, with the highest values in the range 2.5-9.0 ng L-1 for the derivatized analytes. Method accuracy was evaluated on spiked tap water samples: recoveries varied from 85 to 103% and from 75 to 110 % for non derivatized and derivatized compounds, respectively. The obtained results indicate the potentiality of the method for the determination of the investigated analytes at trace levels

SCUOLA ESTIVA DI RICERCA EDUCATIVA E DIDATTICA CHIMICA “ULDERICO SEGRE” Riflettere sulle conoscenze per favorire un apprendimento significativo

Nei giorni 10-15 Luglio 2010 è stata organizzata a Ferrara una scuola di ricerca educativa e didattica chimica “Ulderico Segre” . L'organizzazione è stata a carico della Società Chimica Italiana, divisione di Didattica della Chimica e del progetto laurre Scientifiche in collaborazione con il referente locale, prof. M.C. Pietrogrande. Alla Scuola hanno partecipato circa 20 giovani ricercatori universitari e personale non strutturato (dottorandi e assegnisti). L’obiettivo della scuola è mostrare che per migliorare la propria professionalità di docente è necessario svolgere attività di ricerca in didattica o saper adattare i risultati conseguiti da altri ricercatori. La scelta del tema di riflessione di questa edizione è stata motivata dall’importanza dei modelli per interpretare e prevedere le proprietà delle sostanze e le loro trasformazioni e dalla consapevolezza che la modellizzazione, pur essendo uno strumento molto efficace, non è tuttavia priva di insidie sul piano didattico a causa del rischio di confondere le rappresentazioni dei fenomeni con i fenomeni stessi. Il metodo di lavoro nella Scuola si basa sulla massima interazione tra tutti i partecipanti: un numero limitato di lezioni frontali, seguite da dibattiti, confronti e lavori di gruppo su contenuti di particolare rilevanza concettuale. L’obiettivo è duplice: valutare l’accessibilità dei contenuti considerati e riflettere sui diversi possibili approcci al processo di insegnamento/apprendimento