Identification of derivatives of bisphenol A diglycidyl ether and novolac glycidyl ether in can coatings by liquid chromatography/ion trap mass spectrometry

A reversed-phase liquid chromatographic method combined with fluorescence and multiple mass spectrometric detection in series is presented for the separation and structure elucidation of bisphenol A diglycidyl ether (BADGE) and novolac glycidyl ether (NOGE) derivatives. Atmospheric pressure chemical ionization in the positive ion mode and collision induced fragmentation in the ion trap allowed identification of BADGE- and NOGE-related compounds originating from reactions of the glycidyl ethers with bisphenols, solvents, and chain stoppers. Two extracts from food-can coatings were investigated in detail. It was possible to elucidate the structures of many substances and consequently to draw conclusions about the production of the lacquers.     

Comparison of three types of mass spectrometers for HPLC/MS analysis of perfluoroalkylated substances and fluorotelomer alcohols

The performance of three different types of mass spectrometers (MS) coupled to high performance liquid chromatography (HPLC) was compared for trace analysis of perfluoroalkylated substances (PFAS) and fluorotelomer alcohols (FTOHs). Ion trap MS in the full scan and product ion MS2 mode, time-of-flight (TOF) high resolution MS and quadrupole MS in the selected ion mode as well as triple quadrupole tandem MS were tested. Electrospray ionisation in the negative ion mode [ESI-] was best suited for all instruments and compounds. PFAS could only be separated by a buffered mobile phase, but the presence of buffer suppressed the ionisation of FTOHs. Therefore, two independent chromatographic methods were developed for the two compound classes. Mass spectra and product ion spectra obtained by in-source and collision induced dissociation fragmentation are discussed including ion adduct formation. Product ion yields of PFAS were only in the range of 0.3 to 12%, independent from the applied MS instrument. Ion trap MS2 gave product ion yields of 20 to 62% for FTOHs, whereas only 4.1 to 5.8% were obtained by triple quadrupole tandem MS. Ion trap MS was best suited for qualitative analysis and structure elucidation of branched isomeric structures of PFAS. Providing typical detection limits of 5 ng injected in MS2 mode, it was not sensitive enough for selective trace amount quantification. TOF high resolution MS was the only technique combining high selectivity and excellent sensitivity for PFAS analysis (detection limits of 2 to 10 pg), but lacked the possibility of MS-MS. Triple quadrupole tandem MS was the method of choice for quantification of FTOHs with detection limits in the low pg range. It is also well suited for the determination of PFAS, though its detection limits of 10 to 100 pg in tandem MS mode are about one order of magnitude higher than for TOF MS.     

Analyticity of effective coupling and propagators in massless models of quantum field theory

For massless models of quantum field theory, some general theorems are proved concerning the analytic continuation of the renormalization group functions as well as the effective coupling and the propagators. Starting points are analytic properties of the effective coupling and the propagators in the momentum variablek ², which can be converted into analyticity of - and -functions in the coupling parameter . It is shown that the -function can have branch point singularities related to stationary points of the effective coupling as a function ofk ². The type of these singularities of () can be determined explicitly. Examples of possible physical interest are extremal values of the effective coupling at space-like points in the momentum variable, as well as complex conjugate stationary points close to the realk ²-axis. The latter may be related to the sudden transition between weak and strong coupling regimes in quantum chromodynamics. Finally, for the effective coupling and for the propagators, the analytic continuation in both variablesk ² and is discussed.On leave from the Max-Planck-Institut für Physik und Astrophysik, D-8000 München, Federal Republic of Germany     

Catalysis of O-(para-nitrophenyl) O,O-dimethyl thiophosphate decomposition by chromonic mesophases based on polymerized ionic amphiphiles

The formation of a nematic chromonic mesophase in aqueous solutions of quaternized poly(ethylene imine) has been found using polythermal polarization microscopy. The reaction kinetics of O-(para-nitrophenyl) O,O-dimethyl thiophosphate hydrolysis has been studied by spectrophotometry, and a comparative analysis of the effects of lyotropic liquid crystals constructed as hexagonal and chromonic mesophases on this kinetics has been performed. It has been found that the hydrolysis of the substrate in a nematic chromonic mesophase is accelerated due to the concentration of the reactants.     

Chemische Hilfsreaktionen als Mittel zur Programmerweiterung von ionensensitiven Elektroden

Zusammenfassung Werden im Zusammenhang mit der Probenvorbereitung chemische Hilfsreaktionen in die Messung mit ionensensitiven Elektroden einbezogen, so lassen sich durch ungewöhnlich große Änderungen des Meßkettenpotentials gekennzeichnete Übersteilheiten erzielen, was sich vorteilhaft in einer Erhöhung der Analysengenauigkeit bemerkbar macht. Am Beispiel der Analyse schwefelsaurer Elektrolyte zum Anodisieren von Aluminium wird das Vorgehen beschrieben. Die Säurebestimmung nimmt man mit einer üblichen Glaselektrodenmeßkette vor, wobei die Proben einer Probenvorbereitung mit einem Basengemisch sich überlappender pK-Werte unterzogen werden. Die Aluminiumbestimmung nutzt dagegen die Bildung von Fluoraluminaten verschiedener Koordinationszahl aus. Die Probenvorbereitung erfolgt mit einer fluoridhaltigen Pufferlösung. Der von der Aluminiumkonzentration abhängige Gehalt an Restfluorid wird mit einer fluoridsensitiven Meß-kette gemessen. Die Bildung von Cyanoniccolaten kann analog zur Nickelbestimmung mit einer cyanidsensitiven Meßkette herangezogen werden. Durch einen Vergleich der theoretischen und der gemessenen Potentialänderung wird für die genannten Fälle das Erreichen von Übersteilheiten und die verbesserte Analysengenauigkeit belegt.Vortrag anläßlich der Tagung Euroanalysis I, 28. 8. bis 1. 9. 1972 in Heidelberg.     

The effect of polymeric supports and methods of immobilization on the performance of an optical copper(II)-sensitive membrane based on the colourimetric reagent Zincon

A comparative study on the effect of different immobilization methods and matrix materials on the performance of copper(II)-sensitive membrane layers is presented. The indicator dye Zincon was immobilized in hydrophilic and hydrophobic polymers by various methods including: (a) physical entrapment of the Zincon-tetraoctylammonium ion pair in plasticized PVC, hydrogel, polystyrene, ethyl cellulose, poly-HEMA, AQ-polymer and in sol-gel glass; (b) electrostatic immobilization on an anion exchanger cellulose; and (c) covalent immobilization on cellulose via a sulfatoethylsulfonyl reactive group. The response to copper(II) ion was evaluated kinetically via the initial slope of the change in absorbance within 1 min. Layers made of hydrogel and PVC provide the highest sensitivity, while covalent immobilization is the most reproducible one, and sol-gel layers display the best mechanical stability.     

Reactions in micellar systems

The notion of "green chemistry" has encouraged even synthetic organic chemists to include water as a solvent. Incredible selectivities and activities can be achieved through the addition of amphiphiles with a defined structure. The morphology of supramolecular assemblies or associates formed by surfactants vary according to the temperature and concentration. As a rule, reactions are typically conducted using simple spherical aggregates, that is, micelles in the nanometer range. The strong polarity gradient present between the hydrophilic surface and the hydrophobic core of the micelle means that both nonpolar and polar reagents can be solubilized. This solubilization results in reactants becoming more concentrated within the micelle than in the surrounding water phase and leads to an acceleration of the reaction and causes selective effects. The kinetic treatment of reactions in micellar systems can be accomplished by considering them as microheterogeneous two-phase systems.     

Broken algebra of currents and the Cabibbo angle

Hadron currents are introduced which violate the chiral SU(3) × SU(3) algebra, but leave the subalgebra of SU(2) × SU(2) unchanged. The coefficient of the symmetry breaking current can be related to the Cabibbo angle and the meson mass splitting. Two models are considered which give explicit values for this angle.     

Relation between effective couplings for asymptotically free models

For asymptotically free models with two independent couplings asymptotic expansions are constructed which express one effective coupling in terms of the other. The expansions involve powers (including fractional or irrational exponents) and logarithms. All orders of the-functions are taken into account. The expansions found are complete in the sense that they represent solutions (exact to any order) which generalize all the solutions obtained with the-functions approximated to second order. It is shown that higher orders are relevant since it is not possible in general to reparametrize the system such that the-functions become polynomials of the coupling parameters. The simplifications in case of supersymmetric models are discussed.