Generation and intramolecular reactivity of acyl radicals from alkynylthiol esters under reducing tin-free conditions

[reaction: see text] The radical chain reaction of benzenethiol with alkynylthiol esters provides a new, valuable protocol for the tin-free generation of acyl radicals that arise from intramolecular substitution at sulfur by the initial sulfanylvinyl radicals.     

Flow injection-chemical vapor generation atomic fluorescence spectrometry hyphenated system for organic mercury determination: A step forward

Monomethylmercury and ethylmercury were determined on line using flow injection-chemical vapor generation atomic fluorescence spectrometry without neither requiring a pre-treatment with chemical oxidants, nor UV/MW additional post column interface, nor organic solvents, nor complexing agents, such as cysteine. Inorganic mercury, monomethylmercury and ethylmercury were detected by atomic fluorescence spectrometry in an Ar/H₂ miniaturized flame after sodium borohydride reduction to Hg⁰, monomethylmercury hydride and ethylmercury hydride, respectively. The effect of mercury complexing agent such as cysteine, ethylendiaminotetracetic acid and HCl with respect to water and Ar/H₂ microflame was investigated.The behavior of inorganic mercury, monomethylmercury and ethylmercury and their cysteine-complexes was also studied by continuous flow-chemical vapor generation atomic fluorescence spectrometry in order to characterize the reduction reaction with tetrahydroborate. When complexed with cysteine, inorganic mercury, monomethylmercury and ethylmercury cannot be separately quantified varying tetrahydroborate concentration due to a lack of selectivity, and their speciation requires a pre-separation stage (e.g. a chromatographic separation). If not complexed with cysteine, monomethylmercury and ethylmercury cannot be separated, as well, but their sum can be quantified separately with respect to inorganic mercury choosing a suitable concentration of tetrahydroborate (e.g. 10^? 5 mol L^? 1), thus allowing the organic/inorganic mercury speciation.The detection limits of the flow injection-chemical vapor generation atomic fluorescence spectrometry method were about 45 nmol L^? 1 (as mercury) for all the species considered, a relative standard deviation ranging between 1.8 and 2.9% and a linear dynamic range between 0.1 and 5 μmol L^? 1 were obtained. Recoveries of monomethylmercury and ethylmercury with respect to inorganic mercury were never less than 91%. Flow injection-chemical vapor generation atomic fluorescence spectrometry method was validated by analyzing the TORT-1 certificate reference material, which contains only monomethylmercury, and obtaining 83 ± 5% of monomethylmercury recovered, respectively. This method was also applied to the determination of monomethylmercury in saliva samples.     

Morphological and chemical characterization of weathering products on buried Sasanian glass from central Iraq

This paper discusses the morphological and chemical features of the weathering products on Sasanian glass finds excavated at the ancient Sasanian town of Veh Arda?īr, some 30 km south of Baghdad (Iraq), and dated from the third to the sixth century. All the considered fragments represent soda-lime glass, with MgO contents between 3% and 8%, resulting from the use of soda-rich plant ash as a flux; within this general frame, two productions can be distinguished due to their MgO to K₂O ratio. Four main alteration typologies were observed by visual examination of the excavated samples; these were studied by scanning electron microscopy, energy dispersive X-ray analysis, inductively coupled plasma-mass spectrometry, X-ray diffraction and thermal analysis. Different alteration features were generally observed for samples belonging to the two compositional groups. In particular, samples with higher MgO to K₂O ratios show definitely thinner crusts, associated with alteration plugs going down into the glass. Moreover, gray or black crusts are related to the presence of manganese at significant levels in the original glass.     

Zur quantitativen Bestimmung des Phenols im Harn

Ohne Zusammenfassung     

Determinazione e studio di superficie diS 5 le cui linee principali presentano una notevole particolarità

Sunto Ridottasi la ricerca dei 5-tessuti di curve piane di rango massimo a quella di superficie diS ₅ con 5 sistemi di linee (principali) ad iperpiano tangente fisso, la determinazione di tali superficie, già effettuata in parte dalBol e dalTerracini, riceve un nuovo contributo dal presente lavoro con la scoperta di due soluzioni particolarmente notevoli. Per tali soluzioni vengono rilevate proprietà proiettivo-differenziali dei sistemi di linee principali e proprietà topologiche dei corrispondenti 5-tessuti.     

Partial least-squares modelling of dye fastness to light

Several physicochemical properties (¹³C-n.m.r., spectrophotometric, chromatographic, calorimetric) were measured for a series of 38 azo dyes in order to test the existence of relationships between one or more of these data sets and the fastness of the dyes on polyester fabric. The partial least-squares method was applied; it had previously proved useful in establishing structure/property relationships for the same dyes. It is shown that ¹³C-n.m.r. data can be used successfully to predict dye fastness to light. These data are quickly and cheaply obtained with small amounts of compound.