New functionalizable alkyltrichlorosilane surface modifiers for biosensor and biomedical applications

We report herein three unprecedented alkyltrichlorosilane surface modifiers bearing pentafluorophenyl ester (PFP), benzothiosulfonate (BTS), or novel β-propiolactone (BPL) functionalizable terminal groups. Evidence is provided that these molecules can be prepared in very high purity (as assessed by NMR) through a last synthetic step of Pt-catalyzed alkene hydrosilylation then directly employed, without further purification, for the surface modification of quartz and medical grade stainless steel. Subsequent on-surface functionalizations with amine and thiol model molecules demonstrate the potential of these molecular adlayers to be important platforms for future applications in the bioanalytical and biomedical fields.     

Correlation between biological activity and energies of electronic transitions in benzodiazepines. Negative ion mass spectrometry and ultraviolet absorption spectroscopy study of some derivatives

A correlation between the energies of electronic singlet transitions in benzodiazepines and their biological activity, which was revealed earlier by means of negative ion mass spectrometry with resonance electron capture, has been verified with a UV absorption spectroscopy investigation. Also, it has been noted that the energies of electronic singlet transitions in benzodiazepines are close in value to the ionization energies of atoms Cs, Rb, K, Na, Li and Tl, the cations of which are known to play an important role in nerve cell excitation processes. Copyright 1999 John Wiley & Sons, Ltd.     

Electropolishing of medical-grade stainless steel in preparation for surface nano-texturing

The purpose of this work is to investigate the electropolishing of medical-grade 316 L stainless steel to obtain a clean, smooth, and defect-free surface in preparation for surface nano-texturing. Electropolishing of steel was conducted under stationary conditions in four electrolyte mixtures: (A) 4.5 M H₂SO₄ + 11 M H₃PO₄, (B) 7.2 M H₂SO₄ + 6.5 M H₃PO₄, (C) 6.4 M glycerol + 6.1 M H₃PO₄, and (D) 6.1 M H₃PO₄. The influence of electrolyte composition and concentration, temperature, and electropolishing time, in conjunction with linear sweep voltammetry and chronoamperometry, on the stainless steel surface was studied. The resulting surfaces of unpolished and optimally polished stainless steel were characterized in terms of contamination, defects, topography, roughness, hydrophilicity, and chemical composition by optical and atomic force microscopies, contact angle goniometry, and X-ray photoelectron spectroscopy. It was found that the optimally polished surfaces were obtained with the following parameters: electrolyte mixture A at 2.1 V of applied potential at 80 °C for 10 min. This corresponded to the diffusion-limited dissolution of the surface. The root mean square surface roughness of the electropolished surface achieved was 0.4 nm over 2 × 2 μm². Surface analysis showed that electropolishing led to ultraclean surfaces with reduced roughness and contamination thickness and with Cr, P, S, Mo, Ni, and O enrichment compared to untreated surfaces.     

Simultaneous determination of triazines and their main transformation products in surface and urban wastewater by ultra-high-pressure liquid chromatography–tandem mass spectrometry

This work describes the optimization, validation and application of an ultra-high-pressure liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) method for the quantification and confirmation of 11 compounds (atrazine, simazine, terbuthylazine, terbumeton, terbutryn and their main transformation products) in surface and wastewater samples. Several of these analytes are included in the list of priority substances in the framework on European Water Policy. The application of this method to water samples reveals that the most relevant transformation products (TPs) should be incorporated into current analytical methods to obtain a more realistic knowledge of water quality regarding pesticide contamination. TPs are generally more polar and mobile than parents and can be transported to the aquatic environment more easily than their precursors. This can explain their concentrations found in water, which in many cases are much higher than intact triazines. To efficiently combine UHPLC with MS/MS, a fast-acquisition triple quadrupole mass analyser was used. Working in selected reaction monitoring mode, up to three simultaneous transitions per compound were acquired, allowing a reliable quantification and confirmation at nanogram per litre levels. The method developed includes a pre-concentration step based on solid-phase extraction (OASIS HLB cartridges). Satisfactory recoveries (70–120%) and relative standard deviations (<20%) were obtained for all compounds in different water sample types spiked at two concentrations (0.025 and 0.1 μg/L in surface water; 0.25 and 1.0 μg/L in effluent wastewater; 0.5 and 2.0 μg/L in influent wastewater). The optimized method was found to have excellent sensitivity with instrumental detection limits as low as 0.03 pg. In addition, the influence of the matrix constituents on the ionization efficiency and the extraction recovery was studied in different types of Italian and Spanish surface and urban wastewater. Signal suppressions were observed for all compounds, especially for influent wastewater. The use of isotope-labelled internal standards was found to be the best approach to assure an accurate quantification in all matrix samples.