Giorgio Cevasco

Are ionic liquids a proper solution to current environmental challenges

It is well known that ionic liquids (ILs) possess extraordinary characteristics, making them greener solvents with unique properties, which allow processes that would otherwise be difficult or impossible with common solvents to be carried out. In this review, we describe and discuss, in the light of possible future large scale applications, some fundamental studies showing the efficacy of ILs in several “hot” fields, from dissolution and transformation of biopolymers to extraction and capture of important inorganic components (metals) or pollutants (CO2).

Ecotoxicity of pristine graphene to marine organisms

The ecotoxicity of pristine graphene nanoparticles (GNC1, PGMF) in model marine organisms was investigated. PGMF resulted more toxic than GNC1 to the bioluminescent bacterium Vibrio fischeri and the unicellular alga Dunaliella tertiolecta on the basis of EC50 values (end-points: inhibition of bioluminescence and growth, respectively). No acute toxicity was demonstrated with respect to the crustacean Artemia salina although light microscope images showed the presence of PGMF and GNC1 aggregates into the gut; a 48-h exposure experiment revealed an altered pattern of oxidative stress biomarkers, resulting in a significant increase of catalase activities in both PGMF and GNC1 1mg/L treated A. salina and a significant increase of glutathione peroxidase activities in PGMF (0.1 and 1mg/L) treated A. salina. Increased levels of lipid peroxidation of membranes was also observed in PGMF 1mg/L exposed A. salina.

An improved method for simultaneous analysis of aminothiols in human plasma by high-performance liquid chromatography with fluorescence detection

Altered levels of aminothiols in biological fluids are thought to be an important risk indicator for several diseases, and reliable methods for the accurate determination of aminothiols concentrations in plasma are thus required. In this paper ammonium 5-bromo-7-fluorobenzo-2-oxa-1,3-diazole-4-sulphonate (SBD-BF) is proposed as a convenient fluorogenic derivatizating reagent for the determination of aminothiols (cysteine, cysteinylglycine, homocysteine and glutathione) by HPLC with fluorescence detection. The reactions of SBD-BF with aminothiols at room temperature are about three-times faster than those of ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulphonate (the most frequently employed reagent) at 60 degrees C. The derivatives of SBD-BF with cysteine, cysteinylglycine, homocysteine and glutathione are easily separated by HPLC and their calibration curves show excellent linearity over the range 0.05-20 micromol/L with excellent r(2) values for all analytes. SBD-BF reacts with thiols under mild conditions, i.e. at 25 degrees C over about 30 min, and is proposed as a suitable fluorogenic reagent for thiol derivatization to be introduced in analytical clinical chemistry. The detection limits of Cys, Cys-Gly, Hcy and GSH at a signal-to-noise ratio of 5 were 0.1 microM for Cys, 0.01 microM for Cys-Gly and Hcy, and 0.02 microM for GSH. Furthermore, validation parameters of the proposed method are quite satisfactory. As an application of this method the determination of thiol derivatives in human plasma was carried out on a number of samples.

A facile synthesis of sulfinyl chlorides from thiolacetates

Abstract Alkyl and aryl thiolacetates are converted smoothly into sulfinyl chlorides by sulfuryl chloride in the presence of acetic anhydride.

A simple, sensitive and efficient assay for the determination of d- and l-lactic acid enantiomers in human plasma by high-performance liquid chromatography

A new method for the simultaneous determination of D- and L-lactic acid in human plasma has been developed using high-performance liquid chromatography (HPLC) with fluorescence detection. This method is based on the reaction of lactic acid with (2S)-2-amino-3-methyl-1-[4-(7-nitro-benzo-2,1,3-oxadiazol-4-yl)-piperazin-1-yl]-butan-1-one (NBD-PZ-Val) in the presence of O-(7-azobenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HATU) and N-ethyldiisopropylamine (DIEA) to produce fluorescent diastereomeric derivatives that were easily monitored fluorimetrically at λ(ex)=490 nm and λ(em)=532 nm. The separation was achieved by use of a C18 analytical column (Synergy Hydro 150 mm x 3 mm i.d., 4 μm). The calibration curve was linear over the on-column concentration range of 10-200 μmol/L for D-lactic acid and 0.5-4.0 mmol/L for L-lactic acid. The sensitivity was good with a limit of detection of 5.24 μmol/L for D-lactic acid and 0.15 mmol/L for L-lactic acid. The analytical method was successfully applied to human plasma samples from normal healthy subjects.

A mild and convenient preparation of sulfenyl chlorides from thiolacetates

Abstract Sulfenyl chlorides are obtained easily and in good yields through the reaction of thiolesters and sulfuryl chloride.

The anionic sulphonylamine mechanism in the hydrolysis of aryl sulphamates

Evidence from studies on reactivity, linear free energy relationships, trapping with an amine, and activation data indicates that the unprecedented anionic sulphonylamine (2) is involved in the alkaline hydrolysis of aryl sulphamates.

Ammonium 5-bromo-7-fluorobenzo-2-oxa-1,3-diazole-4-sulphonate: a new fluorogenic reagent for the determination of aminothiols by HPLC.

The measurement of aminothiols such as cysteine (Cys), cysteinyl-glycine (Cys-Gly), homocysteine (Hcy), and glutathione (GSH), as well as the corresponding disulfides, has gained high interest within the biomedical community because such molecules are important biomarkers for a wide range of diseases. In particular, increased total plasma Hcy is now considered a risk factor for cardiovascular disorders(1) as well as other degenerative conditions. Although various methods for the measurement of aminothiols are available, HPLC coupled with fluorometric detection is one of the most suitable techniques for determination of minute amounts of thiols(2). Most methods require precolumn derivatization, and although different types of fluorogenic reagents for thiols have been proposed, the most commonly used and sensitive reagent is the commercially available ammonium 7-fluorobenzo-2-oxa-1,3-diazole-4-sulfonate (SBD-F)(3). With this method the completion of the reaction takes a very long time and the conditions required are quite strict, i.e., derivatization must be carried out at 60 °C for a 1-h period in a moderately alkaline medium (pH = 9.5) in the presence of excess reagent. Moreover, fast …

HPLC determination of D-3-hydroxybutyric acid by derivatization with a benzofurazan reagent and fluorescent detection: application in the analysis of human plasma.

A simple and sensitive new method for the determination of D-3-hydroxybutyric acid (D-3-HBA) in human plasma after derivatization is described. The proposed method is based on the reaction of (2S)-2-amino-3-methyl-1-[4-(7-nitro-benzo-2,1,3-oxadiazol-4-yl)-piperazin-1-yl]-butan-1-one (NBD-PZ-Val) with D-3-HBA in the presence of O-(7-azobenzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate (HATU) and N-ethyldiisopropylamine (DIEA) to produce a fluorescent derivative. The formed derivative was monitored fluorimetrically at λ(ex)=489 nm and λ(em)=532 nm. The HPLC analysis was carried out by use of a C18 analytical column (Synergy Hydro 150 mm × 3 mm, i.d., 4 μm) with a binary gradient elution program of 0.1% aqueous trifluoroacetic acid versus methanol. The method showed satisfactory linearity (r(2)=0.9997) in the range from 20 to 500 μmol/L. The limit of detection (LOD) of the method was 7.7 μmol/L, while the limit of quantitation (LOQ) was 25.8 μmol/L. The analytical method was successfully applied to human plasma samples from normal healthy subjects.

THE EFFECT OF LEAVING GROUP VARIATION ON REACTIVITY IN THE DISSOCIATIVE HYDROLYSIS OF ARYL 3,5-DIMETHYL-4-HYDROXYBENZENESULFONATES

The hydrolysis of aryl esters of 3,5-dimethyl-4-hydroxybenzenesulfonic acid in moderately to strongly alkaline aqueous solution follows a dissociative pathway with the participation of a sulfoquinone (thioquinone dioxide) intermediate. Bronsted-type correlation between log kapp and pKLG and inspection of the effective charge changes involved in the reaction further support the ElcB mechanism. From this and previous studies it appears that aryl esters of hydroxyarenesulfonic acids seem to be more inclined to hydrolyse through dissociative pathways than the corresponding hydroxyarenecarboxylic acids esters.