Giuseppe Giorgio Bombi

Mathematical functions for the representation of chromatographic peaks

About ninety empirical functions for the representation of chromatographic peaks have been collected and tabulated. The table, based on almost 200 references, reports for every function: (1) the most used name; (2) the most convenient equation, with the existence intervals for the adjustable parameters and for the independent variable; (3) the applications; (4) the mathematical properties, in relation to the possible applications. The list includes also equations originally proposed to represent peaks obtained in other analytical techniques (e.g. in spectroscopy), which in many instances have proved useful in representing chromatographic peaks as well; the built-in functions employed in some commercial peak-fitting software packages were included, too. Some of the most important chromatographic functions, i.e. the Exponentially Modified Gaussian, the Poisson, the Log-normal, the Edgeworth/Cramér series and the Gram/Charlier series, have been reviewed and commented in more detail.

Aluminium toxicity and metal speciation: established data and open questions

Histopathological findings in humans and extensive toxicological investigation in vivo and in vitro point to an unambiguous neurotoxic potency of AI(III). Experimental toxicology with aqueous AI(III) is very difficult owing to the complex and somewhat uncontrollable aqueous chemistry of the metal centre in the neutral range. The choice of neutral, hydrolytically stable synthetic toxins makes possible both the control of metal speciation and of analytical metal concentration down to about 1 mM in neutral buffered solutions. The employment of less stable complexes like Al2(citrate)2(H2O)6 and AI(lactate)3 or of ordinary salts is unavoidably complicated by the precipitation of Al(OH)3 under the same conditions. In spite of this, the choice of a carefully designed protocol, based on ensuring well defined steps, enables one to successfully control the analytical metal concentration down to 10 μM AI(III). The control of the metal speciation at these concentration levels remains an open question.

Complexation of 2-hydroxynicotinic and 3-hydroxypicolinic acids with zinc(II). Solution state study and crystal structure of trans-diaqua-bis-(3-hydroxypicolinato)zinc(II)

Abstract The interactions between zinc(II) and the two ligands 2-hydroxynicotinic acid (HNic) and 3-hydroxypicolinic acid (HPic) have been investigated by means of potentiometric titrations in aqueous 0.6 m (Na)Cl at 25 °C. In both cases, only mononuclear complexes are formed. The qualitative and quantitative results obtained have been confirmed in part by UV–Vis spectrophotometry and 1H NMR spectroscopy. The complex trans-diaqua-bis-(3-hydroxypicolinato)zinc(II) was obtained as a crystal and examined by X-ray crystallography. The thermodynamic results allow drawing some conclusions regarding the extent of Zn(II) interference in a hypothetical chelation therapy treatment of aluminium or iron overload with these two ligands.

Application of electrochemical methods to iodatometric titrations

SummaryThe application of biamperometry and bipotentiometry to the titration of HgI, SCN−, SbIII and TlI with iodate has been investigated, Probable errors range from 0.16% for SbIII to 0.96% for SCN−, for quantities between 10−5 and 2×10−4moles.ZusammenfassungEs wird über die Verwendung von biamperometrischen und bipotentiometrischen Methoden bei jodatometrischen Titrationen von HgI, SCN−, SbIII und TlI berichtet.Die wahrscheinliche Abweichung des Verfahrens beträgt 0,16% (SbIII) bis 0,96% (SCN−) für Mengen von 10−5 bis 2 · 10−4 Mol.