Suitability of hollow fibre liquid-phase microextraction for the determination of acidic pharmaceuticals in wastewater by liquid chromatography-electrospray tandem mass spectrometry without matrix effects

The applicability of hollow fibre liquid-phase microextraction (LPME), as an alternative to solid-phase extraction (SPE), for the extraction/enrichment of acidic drugs (e.g. ibuprofen, clofibric acid, bezafibrate, etc.) from water samples prior to the determination by LC-ESI-MS-MS has been evaluated. After LPME method optimisation, it was found that this technique can provide very clean extracts, which do not lead to signal suppression during LC-ESI-MS-MS analysis of the analytes. The limits of quantification (0.5-42 ng/L) are suitable for the analysis of these drugs in wastewater. However repeatability needs to been improved (intra-day R.S.D. = 3.4-32%), which may be expected by automation and the development of commercially available devices and fibres specially prepared for analytical purposes. The method was finally applied to wastewater samples (treated and untreated) and results comparable to SPE were obtained.     

Synthesis of fused or not β-lactam-biaryl hybrids by free radical aryl-aryl coupling of 2-azetidinone-tethered haloarenes

cis and trans-Aryl-2-azetidinone-tethered haloarenes can be stereoselectively prepared using the ketene-imine cyclization. These β-lactam-tethered haloarenes were used for the regiocontrolled preparation of β-lactam-biaryl hybrids including fused tetracyclic biaryl-2-azetidinones as well as C4-dearylated not fused biphenyl‐2-azetidinones via aryl-aryl radical cyclization and/or rearrangement. Alternatively, trans-dibenzocarbacephems could be stereoselectively prepared, both in racemic and enantiopure form, through the Staudinger reaction between phenanthridine and activated ketenes.     

A novel one-step approach for the preparation of alpha-amino acids,alpha-amino amides,and dipeptides from azetidine-2,3-diones

A remarkable reaction of azetidine-2,3-diones with primary as well as secondary amines, and water is presented. Simply by varying the nucleophile, an unprecedented one-step synthesis of alpha-amino acids, alpha-amino amides, and dipeptides, was developed in both the racemic and optically pure forms. The current mechanistic hypothesis invokes a concerted process involving CO extrusion. However, a stepwise pathway can also account for these novel transformations.     

Non-metathetic behavior patterns of Grubbs' carbene

Grubbs' carbene complex [Cl(2)(Cy(3)P)(2)Ru=CHPh] and its second-generation counterpart [Cl(2)(Im)(Cy(3)P)Ru=CHPh] have demonstrated remarkable efficiency metathesizing olefins. Furthermore, a growing number of newly discovered catalytic processes mediated by this complex broaden its synthetic utility beyond olefin metathesis. In addition, the ready availability of these stable ruthenium-based catalysts coupled with their tolerance toward a wide variety of common functional groups make Grubbs' catalysts very convenient synthetic tools. This paper presents recent advances in the non-metathetic behavior patterns of Grubbs' carbene.     

Flow-injection analysis-spectrophotometric determination of nitrite and nitrate in water samples by reaction with proflavin

A flow-injection manifold is proposed for determination of nitrite based on the reaction with 3,6-diamino acridine (proflavin sulfate) in hydrochloride acid medium. The assembly is adapted for nitrate determination by including a reductive column filled with copperized cadmium. The influence of foreign substances is also studied. The method gives a linear calibration graph over the range 0.06-4 mg 1(-1) nitrite, with an RSD <0.5%. The method was applied to nitrite and nitrate determinations in either waste water or coastal marine water samples.     

Potentiometric study of the acid-base equilibrium of loprazolam at 25 °C in 0.1M NaCl medium

The acid-base behaviour of Loprazolam has been studied using an automated potentiometric titration system. The temperature was kept constant at 25 °C and the ionic medium was 0.1 mol dm^–3 NaCl in different ethanol-water mixtures (5–20%). The values of the constants obtained at the different ethanol compositions have been extrapolated to give the corresponding stoichiometric constant in water, log = 6.39 ± 0.15     

Screening of Contaminants of Emerging Concern in Surface Water and Wastewater Effluents,Assisted by the Persistency-Mobility-Toxicity Criteria

Contaminants of emerging concern (CECs) are compounds of diverse origins that have not been deeply studied in the past which are now accruing growing environmental interest. The NOR-Water project aimed to identify the main CECs and their sources in the water environment of Northern Portugal–Galicia (located in northwest Spain) transnational region. To achieve these goals, a suspect screening analytical methodology based on the use of liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) was applied to 29 sampling sites in two campaigns. These sampling sites included river and sea water, as well as treated wastewater. The screening was driven by a library of over 3500 compounds, which included 604 compounds prioritized from different relevant lists on the basis of the persistency, mobility, and toxicity criteria. Thus, a total of 343 chemicals could be tentatively identified in the analyzed samples. This list of 343 identified chemicals was submitted to the classification workflow used for prioritization and resulted in 153 chemicals tentatively classified as persistent, mobile, and toxic (PMT) and 23 as very persistent and very mobile (vMvP), pinpointing the relevance of these types of chemicals in the aqueous environment. Pharmaceuticals, such as the antidepressant venlafaxine or the antipsychotic sulpiride, and industrial chemicals, especially high production volume chemicals (HPVC) such as ε-caprolactam, were the groups of compounds that were detected at the highest frequencies.     

Synthesis and evaluation of calystegine B2 analogues as glycosidase inhibitors.

A practical synthesis of polyhydroxylated 6-oxa-nor-tropanes incorporating the essential structural features of calystegine B(2) from 5-deoxy-5-thioureido and 5-ureido-L-idofuranose precursors is presented. The methodology relies on the ability of pseudoamide-type nitrogen atoms (thiourea, urea, and carbamate) to undergo nucleophilic addition to the masked aldehyde group of the monosaccharide. The generated hemiaminal functionality may further undergo in situ intramolecular glycosidation to give the bicyclic aminoacetal compounds, the whole process being favored by the anomeric effect. A series of derivatives bearing different substituents at nitrogen has been prepared and screened against several glycosidases in comparison with xylonojirimycin-type piperidine analogues. Interestingly, strong and highly specific inhibition of bovine liver beta-glucosidase was observed for 6-oxacalystegine B(2) analogues incorporating aromatic pseudoaglyconic groups. On the basis of these data, a 1-azasugar inhibition mode is proposed for this family of glycomimetics.