Pier Giorgio Desideri

The mechanism of ion exchange with algenic acid

Abstract The exchange mechanism which determines the retention capacity of alginic acid has been investigated. Chromatographic, pH, and viscosity measurements, performed with several metal ions, have permitted us to show that ion exchange is not the only mechanism but that the influence of the two vicinal hydroxyl groups on the retention capacity of alginic acid is also important.

Soap thin-layer chromatography of some primary aliphatic amines

Abstract The chromatographic characteristics of nine primary aliphatic amines have been studied using soap thin-layer chromatography. The influence of the type of detergent and its concentration, of the organic solvent and of the acid concentration on the chromatographic behaviour of these amines was investigated. Many separations that cannot be effected with either ion-exchange or reversed-phase chromatography have been effected.

Alginic acid, a new thin layer material : Part I

Abstract Alginic acid is proposed as a new stationary phase for TLC. The effects of the distance moved by the solvent front, temperature, hydrogen ion concentration of the eluents and the thickness of the layers on the R F values of some common elements have been extensively investigated. Characteristic R F values of some common elements are reported. The chromatographic properties of alginic acid and carboxymethylcellulose were compared.

Reversed-phase and soap thin-layer chromatography of peptides.

Abstract The chromatographic behaviour of 38 peptides on layers of silanized silica gel alone and impregnated with anionic and cationic detergents has been investigated. On the basis of the comparison with the amino acid constituents, it has been possible to predict the sequence of the affinities of the peptides with the different solvents. Many separations have been carried out on layers impregnated with 4% dodecylbenzenesulphonic acid solution.

Soap thin-layer chromatography of sulphonamides and aromatic amines

Abstract Using soap thin-layer chromatography, we investigated the behaviour of sulphonamides and many primary aromatic amines. The influence on the chromatographic behaviour of the kind of detergent, the organic solvent percentage in the eluent in the presence and absence of acids, and the apparent pH of the eluent has been widely investigated. Many separations that cannot be effected on ion exchangers have been carried out.

Analysis of organic compounds in Antarctic snow and their origin

Organic compounds extractable with n-hexane were identified and quantitatively determined in pack, surface and deep snow samples taken at different depths and collected at several altitudes above sea level from Antarctica during the 1993/94 Italian expedition. The comparison between the composition of organic compounds in snow and the ones in pack and sea-water samples pointed out that the three matrices substantially contain the same biogenic and anthropogenic organic compounds. The contribution of marine aerosol to organic content in the snow is confirmed by the enrichment ratios calculated for the more representative classes of identified compounds (n-alkanes, phthalates and low molecular weight alkylbenzenes). The changes in the composition of organic compounds in snow as the altitude increases seem to depend on the dimensional spectrum of the aerosol. Thus, smallest particles, richest in surfactant material, reach the highest altitudes.

Soap thin-layer chromatography of primary aromatic amines

Abstract The chromatographic behaviour of 35 primary aromatic amines was investigated by soap thin-layer chromatography, the amount of detergent on the layer and the concentration of methanol and hydrochloric acid in the eluent being varied. The RMversus pH trends of the different amines on layers of silanized silica gel, alone and impregnated with 2% and 4% triethanolamine dodecylbenzenesulphonate solutions, are discussed. Several interesting separations that cannot be effected by either ion-exchange or reversed-phase chromatography were carried out.

Reversed-phase and soap thin-layer chromatography of amino acids

The chromatographic characteristics of 33 amino acids have been studied using soap thin-layer chromatography (TLC). The influence of the type of detergent, the organic solvent and the acid concentration in the eluent on the chromatographic behaviour of the amino acids was investigated. Many interesting separations that cannot be effected by ion-exchange TLC have been performed.

High-performance thin-layer chromatography of 2,4-dinitrophenyl-amino acids on layers of RP-a8, RP-18 and ammonium tungstophosphate

Abstract The chromatographic characteristics of eighteen DNP-amino acids, of dinitrophenol and dinitroaniline were studied on RP-18 and RP-18 plates eluted with aqueous—organic solutions and with mixtures of organic solvents. The optimum conditions for the separation of the highest number of compounds were studied and a two-dimensional chromatogram is reported. On home-made layers of ammonium tungstophosphate, water, aqueous solutions of ammonium nitrate and nitric acid and water—methanol mixtures were used as eluents to separate the pairs of DNP-amino acids which exhibit the same chromatographic behaviour on RP-8 and RP-18 plates.

Electrochemical behavior of aniline in alkaline solutions

Summary The electrochemical behavior of aniline in aqueous alkaline solutions on smooth platinum, platinized platinum, graphite, and gold electrodes has been investigated. The influence of pH, aniline concentration, and scanning potential rate on the electrode poisoning has been studied. The coulometric data have shown that the oxidation products of aniline are: azobenzene and N-phenylquinonediimine. The possibility of the formation of benzidine and of reaction products between N-phenylquinonediimine and aniline is discussed.