Ion-exchange resins in non-aqueous solvents-I Sorption rates of p-nitroaniline and the effects of small amounts of water

The rates of sorption of p-nitroaniline onto three hydrogenform resins in methanol, ethanol, n-propanol, isopropanol, n-butanol, acetonitrile, benzene, acetic acid and dioxan are reported. Two of the resins are typical gel-type, microreticular, sulphonated resins and the third is a new, highly porous and rigid, macroreticular, sulphonated resin, Amberlyst 15. There appears to be a correlation between viscosity or dielectric constant and the time for maximum sorption or maximum distribution coefficient when the alcohols are used, but no correlation for all the solvents is apparent. The macroreticular resin still functions when dry, even in the presence of non-polar solvents, but the microreticular resin does not. Small amounts of water present in the solvent or resin aid the sorption of the amine onto both types of resin. The effect of mesh size and cross-linkage are examined.     

The photometric titration of mercury with trien

A mercury(II) solution containing copper ion can be titrated photometrically at pH 4.7 with triethylenetetramine solution (trien) after the addition of iminodiacetic acid (IDA) ; IDA causes a reversal of the effective formation constants of Hg-trien and Cu-trien and permits the titration. Copper-trien which absorbs at 580 mμ serves as the indicator for the titration. Mercury can be determined in presence of many other metals with an accuracy of about 1%; the main interferences are iron-(III), nickel, bismuth and chloride ion.     

Observation of a narrow resonance near the pp threshold

Annihilation and elastic cross-sections of $\text{p}$p have been measured between 400 and 850 MeV/c. In both cross-sections a resonance is observed at a mass of 1939 ± 3 MeV. For its natural width τ ? 4 MeV is obtained.     

Inelastic hadron-nucleus interactions at 20 and 37 GeV/c

The experiment studies charged particle production for π^?, K^?, and $\text{p}$ interactions on nuclei at 20 and 37 GeV/c at the CERN SPS. A non-magnetic detector, consisting of CsI(Tl) scintillation and lucite ?erenkov counters, distinguishes between fast particles, mainly pions, and slow particles, mainly nucleons, with a cut at velocity β ≈ 0.7. Angular distributions, multiplicity distributions and correlations of slow and fast particles were analysed. It is shown that the measurement of the correlations can provide a critical test for different theoretical models of the hadron-nucleus interaction. At the energies studied so far a systematic deviation from KNO scaling is observed. This gives further support to the “standard picture” of the hadron-nucleus interaction and it contrasts with predictions of the coherent-tube model. The regularity observed for the angular distribution of fast secondaries as a function of the number of slow particles can only be explained by combining features predicted by different models.     

Untersuchung von57Co mit der Reaktion57Fe(p,n)57Co

A neutron time-of-flight investigation of the⁵⁷Fe(p, n)⁵⁷Co reaction performed at bombarding energies of 4.9, 5.6 and 6.2 MeV results in new energy levels of⁵⁷Co. In addition, gamma spectra andn-γ-coincidence spectra were taken to complete the decay scheme of⁵⁷Co up to an excitation energy of 4 MeV.     

A thermodynamic study of struvite+water system

Equilibrium analysis of the system with MgNH₄PO₄·6H₂O (struvite) is taken as an interesting example of two-phase system where a change in solid phase composition (conversion) is affected by hydrolytic phenomena. The problem is presented in a comprehensive manner, based on results obtained from calculations made according to iterative computer program. The complex nature of phenomena occurred, with side effects resulting from presence of carbonate species, is explained. The analytical and physicochemical aspects of the matter are considered.     

Separation and indirect detection of small-chain peptides using chromophoric mobile phase additives

Ruthenium(II) 1,10-phenanthroline, Ru(phen)3(2+), and ruthenium(II) 2,2'-bipyridyl, Ru(bipy)3(2+), salts were evaluated as mobile phase additives for the liquid chromatographic separation of small-chain peptides on a polystyrene-divinylbenzene copolymeric (Hamilton PRP-1) stationary phase. In a basic mobile phase peptides are anions, and retention, resolution and detection occur because of the interactions between the stationary phase, the RuII complex and the peptide anion. Since the RuII complex concentration changes in the analyte band relative to the background eluent RuII complex concentration, the peptide can be detected by indirect photometric detection using the wavelength where the RuII complex absorbs. Peptide analyte peaks may be positive or negative depending on the counter-anion and its concentration. Small-chain peptides that do not contain chromophoric side-chains are detected without derivatization at about 0.1 nmol injected at a 3:1 signal-to-noise ratio. Factors that affect retention, resolution and indirect photometric detection are the RuII complex, its mobile phase concentration, mobile phase pH and solvent composition, and the type and concentration of the mobile phase counter-anion and/or buffer anion.     

Anion-exchange separation and determination of bisphosphonates and related analytes by post-column indirect fluorescence detection

Bisphosphonic acids and their salts can be detected after their liquid chromatographic separation by post-column indirect fluorescence detection (IFD). After separation the analyte is combined with the highly fluorescent Al³⁺–morin (2′,3,4′,5,7-pentahydroxyflavone) solution and fluorescence decreases because of the formation of the nonfluorescent Al³⁺–bisphosphonate complex. The decrease in fluorescence is proportional to the amount of bisphosphonate present. Separation of the multivalent anionic bisphosphonate analytes from other anions and sample matrix is achieved on a strong base anion-exchange column with a strong, basic eluent. The post-column reaction variables, which influence IFD, are identified and optimized for the detection of the bisphosphonates after separation on the anion exchanger. The method is selective, since only a few anions will undergo a reaction with the Al³⁺–morin solution, and sensitive, detection limit for difluoromethylene bisphosphonate, F₂MDP, is 4 ng for S/N=3. The separation–IFD method can be applied to the determination of bisphosphonates, such as F₂MDP, ethane-1-hydroxy-1,1-bisphosphonic acid, dichloromethylene bisphosphonic acid, 4-amino-1-hydroxybutane-1,1-bisphosphonic acid, in biological samples. The separation–IFD method is also applicable to the detection of inositol phosphate anions.