A New Protocol for the Removal of Dimethoxytrityl Ether Groups Derived from Primary Alcohols

Abstract: A range of primary alcohol dimethoxytrityl ethers were deprotected by using ultrasound at ambient temperature (yields 69-100%). The new procedure may find utility in the synthesis of materials of biological interest, such as oligonucleotides.     

Investigation of the quantitative properties of the quadrupole orthogonal acceleration time-of-flight mass spectrometer with electrospray ionisation using 3,4-methylenedioxymethamphetamine

This paper describes the investigation of the potential of a quadrupole orthogonal acceleration time-of-flight mass spectrometer (Q-TOF) equipped with an atmospheric pressure ionisation interface for quantitative measurements of small molecules separated by reversed phase liquid chromatography. To this end, the detection limits and linear dynamic range in particular were studied in an LC/MS/MS experiment using 3,4-methylenedioxymethamphetamine standards and 3,4-methylenedioxyethylamphetamine for internal standardisation. In a second phase, the experiment was repeated with real biological extracts (whole blood, serum, and vitreous humour). A calibration for 3,4-methylenedioxymethamphetamine and its metabolite 3,4-methylenedioxyamphetamine was prepared in each of these matrices again using 3,4-methylenedioxyethylamphetamine as internal standard. The resulting quantitative data were compared with those obtained by liquid chromatography with fluorescence detection for the same extracts. The Q-TOF results revealed excellent sensitivity and a linear dynamic range of nearly four decades (2-10 000 pg on-column, r(2) = 0.9998, 1/x weighting). Furthermore, all the calibration curves prepared in biological material were superimposable, LC/MS/MS and LC-fluorescence, and the quantitative results for actual samples compared very favourably. It was concluded that the Q-TOF achieves a linear dynamic range for quantitative LC/MS/MS work exceeding that of fluorescence detection and at much better absolute sensitivity. Copyright 1999 John Wiley & Sons, Ltd.     

Solar Water Disinfection to Produce Safe Drinking Water: A Review of Parameters,Enhancements, and Modelling Approaches to Make SODIS Faster and Safer

Solar water disinfection (SODIS) is one the cheapest and most suitable treatments to produce safe drinking water at the household level in resource-poor settings. This review introduces the main parameters that influence the SODIS process and how new enhancements and modelling approaches can overcome some of the current drawbacks that limit its widespread adoption. Increasing the container volume can decrease the recontamination risk caused by handling several 2 L bottles. Using container materials other than polyethylene terephthalate (PET) significantly increases the efficiency of inactivation of viruses and protozoa. In addition, an overestimation of the solar exposure time is usually recommended since the process success is often influenced by many factors beyond the control of the SODIS-user. The development of accurate kinetic models is crucial for ensuring the production of safe drinking water. This work attempts to review the relevant knowledge about the impact of the SODIS variables and the techniques used to develop kinetic models described in the literature. In addition to the type and concentration of pathogens in the untreated water, an ideal kinetic model should consider all critical factors affecting the efficiency of the process, such as intensity, spectral distribution of the solar radiation, container-wall transmission spectra, ageing of the SODIS reactor material, and chemical composition of the water, since the substances in the water can play a critical role as radiation attenuators and/or sensitisers triggering the inactivation process.     

The identification and determination of cationic dyes in dye liquors for acrylic fibre and extracted from finished products

Summary High performance mode TCL on silica gel followed by scanning densitometry has been shown to be a satisfactory method for the identification and for the quantitative prior analysis of dye liquors to be used for acrylic fibres and also for dyes extracted from finished products. The preferred extractant is pyridine-acetic acid-water (20:5:75 v/v). Formerly at Montifibre UK Ltd, Coleraine, BT51 3QA, Northern Ireland, UK     

Analysis of Titan tholin pyrolysis products by comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry

The reddish brown haze that surrounds Titan, Saturn's largest moon, is thought to consist of tholin-like organic aerosols. Tholins are complex materials of largely unknown structure. The very high peak capacity and structured chromatograms obtained from comprehensive two-dimensional GC (GC x GC) are attractive attributes for the characterization of tholin pyrolysis products. In this report, GC x GC with time-of-flight MS detection and a flash pyrolysis inlet is used to characterize tholin pyrolysis products. Identified pyrolysis products include low-molecular-weight nitriles, alkyl substituted pyrroles, linear and branched hydrocarbons, alkyl-substituted benzenes and PAH compounds. The pyrolysis of standards found in tholin pyrolysate showed that little alteration occurred and thus these structures are likely present in the tholin material.