Chromatographic behaviour of alkaloids on thin layers of cation exchangers. II. Alginic acid, Rexyn 102, Dowex 50-X4 and CMCNa.

The chromatographic behaviour of 48 alkaloids on cation exchangers with cellulose, paraffin and polystyrene matrices in both the acid and sodium salt forms has been investigated. Water-organic solvent mixtures, aqueous buffer solutions and organic and mineral acid solutions in both water and in aqueous-organic solvents have been used as eluents. The retention mechanisms of these compounds on alginic acid, Rexyn 102 (Hplus) and Dowex 50-X4 (Hplus) thin layers are discussed. Interesting separations of the alkaloids were carried out on alginic acid and Rexyn 102 (Hplus).     

Chromatographic behaviour of phenols on thin layers of cation and anion exchangers. II. Dowex 50-X4 and Rexyn 102.

The chromatographic characteristics of 58 phenols on Rexyn 102 and Dowex 50-X4 thin layers in both the acidic and sodium salt forms have been studied, using elution with water, water-alcohol mixtures and aqueous salt solutions at different pH values. The influence of the percentage of alcohol, the pH and the ionic strength on the chromatographic behaviour of these phenols was investigated. The validity of the relationships among the RF values, the pH of the eluent and the pKa of the phenol has been verified on Dowex 50-X4 (Na+) thin layers. It has been shown that from the RFac, RFalk and pKa values of the different phenols, it is possible to predict their behaviour over the whole pH range and therefore to select the best conditions for their chromatographic separation.     

Chromatographic and electrophoretic behaviour of primary aromatic amines on anion-exchange thin layers

The use of polystyrene-based anion exchangers with aqueous eluents for the separation of primary aromatic amines has been investigated, and extended with satisfactory results to microcrystalline cellulose, cellulose-based anion-exchangers and sodium CM-cellulose layers.Interesting separations of the amines have also been effected electrophoretically on AG 1-X4 layers.The use of water-organic solvent mixtures on polystyrene-based cation exchangers is discussed.     

Behaviour of Mo,Al, As,Cs, Sn,Sb, Pd,Rh, Ru,Ge, Se and Te on the macroporous resin AG MP-1 in alkaline medium

The behaviour of Mo and some other elements on Ag MP-1 in alkaline medium was investigated. Equilibrium distribution coefficients, K_d, are presented for Mo on the anion exchangers AG 1-X2, AG 1-X4, AG 1-X8 and AG MP-1, and for some elements on AG MP-1 in alkaline medium. An anion exchange chromatographic separation of Mo from some of these elements is described and some results obtained with this method are reported.     

Thin Layer Chromatographic Study of Bauxite and Quantitative Estimation of Co-Existing Al3+, Fe2+ and Ti4

 Thin layer chromatography in combination with spectrophotometry and titrimetry has been used to evaluate chromatographic characteristics of bauxite constituents. The retention behaviors of four major constituents (Al3+, Fe2+, Ti4+, Si4+) in bauxite mineral have been examined on plain and modified layers of silica gel G, silica gel H and cellulose with mobile phases containing aqueous sodium chloride, formic acid and hydrochloric acid. Ternary separation of Al-Fe-Ti was achieved on chromatographic plates made of silica gel H. The pH effect and presence of impurity elements in samples, nature of stationary phases on the ternary separation and detection limits of bauxite constituents were studied. Silicon in bauxite was detected on cellulose plates. Quantitative determinations of Al3+, Fe2+ and Ti4+ on silica gel H impregnated with sodium formate layers were achieved by titrimetry and spectrophotometry.     

Organic acid solutions in the chromatography of inorganic ions. V. Thin-layer chromatography in tartrate-water-ethanol media

Summary We present a study of the chromatographic behaviour of sixty inorganic ions on cellulose thin layers, employing acidic solutions of tartaric acid-water-ethanol at its own pH and basic solutions of tartaric acid-water-ethanol-NH₄OH at about pH 9 as eluents. Generally the ions show a decreasing migration rate with increasing percentage of ethanol, at constant tartrate molarity, in acidic and basic solutions. For some ions the decrease in migration rate is the same in acidic and basic media, for others with a complexing capacity it is greater in basic than in acidic media. Some interesting separations are shown.This work has been in part supported by C.N.R. of Italy.     

Thin-layer chromatography of a number of inorganic ions on sulfoethyl cellulose in acetic acid and in acetic acid-ammonium acetate media

Summary The thin-layer chromatographic behaviour of 51 inorganic ions has been studied on a strongly acidic cation exchanger, sulfoethyl cellulose, using acetic acid and acetic acid-ammonium acetate media. Feasibilities for effective separations of analytical interest are demonstrated on the cellulose layer (0.50mm thick) in both media.     

Synthesis of Cellulose Tris (4-Methylbenzoate) as Gas Chromatographic Stationary Phase and its Characterization

Cellulose (MC) is the most accessible optically active polymer. Its benzoate and phenylcarbamate derivatives exhibit a high chiral recognition ability for a variety of racemic compounds as chiral stationary phases (CSPs) for high performance liquid chromatography1-3. However, the application of cellulose derivatives in gas chromatography has seldom been reported except that Zou reported cellulose tribenzoate (CTB) which was used as a stationary phase for gas chromatography 4. Cellulose and…     

Rapid and quantitative separation of nicotinamide and its N1-methylated metabolite by Dowex AG50-X4 chromatography.

The use of column chromatography with Dowex AG50-X4 resin has allowed the quantitative separation of nicotinamide from its primary metabolite, N1-methylnicotinamide. Although the sensitivity is similar to earlier high-performance liquid chromatographic methods, this procedure allows multiple assays to be carried out simultaneously in a matter of minutes. This method should be useful to study nicotinamide methyltransferase activity in either whole cells or extracts, and is particularly well suited to screen column fractions for enzyme purification purposes.     

Matrix separation of palladium and iridium by the cellulose anion exchanger Cellex T and the subsequent determination of palladium at theμg/g-level

The preconcentration and separation of palladium and iridium from base metals is studied with cellulose (Cellex T) and styrene-divinylbenzene (Varion AT 400) anion exchangers. In spite of lower capacity of Cellex T to chloride complexes of Pd and Ir, it allowed to get a higher preconcentration factor. Yields of 92–99% are achieved for Pd and 96–97% for Ir from the solutions containing great excess of base and heavy metals. Graphite furnace atomic absorption spectrometry is used for the final measurements. The procedure has been applied to the determination of palladium in natural samples.     

Comparative study of chromatography on thin layers impregnated with organic stationary phases. Chromatographic separation of nitrophenols.

The chromatographic behaviour of nitrophenols on thin layers of silica gel and cellulose was compared, both without impregnation and impregnated with non-aqueous polar stationary phases (formamide, dimethylformamide) and less polar stationary phases (liquid paraffin, octan-1-ol, 1-bromonaphthalene). Cellulose is preferred when using formamide or dimethylformamide if a pure partition process is required. For each particular analyte a certain amount of the stationary phase is always required to suppress the adsorption activity of silica gel. Separation by reversed-phase thin-layer chromatography is strongly affected by the type of stationary phase (the possibility of forming charge-transfer complexes with 1-bromonaphthalene) and its support (the acidic properties of silica gel and its adsorption activity), the mobile phase (content of organic modifier, pH, presence of salts) and the properties of the solutes (polarity, ionizability).     

New method of automatic photometric determination of proteins in whole milk. II. Linearity, selectivity, and specificity

A new procedure for the preconcentration of p.p.b. concentrations of chromate from aqueous solutions has been developed. Water samples containing chromate are acidified to pH 5 and passed through an anion-exchange resin bed (AG1-X4, 100–200 mesh. Cl^? form) in ascending flow, so that the chromate is adsorbed in a narrow zone at the lower end of the resin bed. The chromate is eluted rapidly with small volumes of an acidic reductant solution which reacts with chromate on the column to form chromium(III) during the actual elution step, thus producing very high concentration factors.     

Thin-layer chromatography of homopyrimidazole derivatives.

The chromatographic behaviour of 14 homopyrimidazole derivatives has been studied on thin layers of silica gel, aluminium oxide and ammonia-saturated silica gel. The relationships between structure and chromatographic behaviour, as well as the most suitable systems for separating the individual derivatives, are discussed on the basis of RF values. The delta RMg values, showing the effect on the polarity, are given for certain functional groups.     

Investigation of the usefulness of NTA, EDTA and DTPA in separation of some platinum metals on cellulose exchangers

The possibility of using NTA, EDTA and DTPA as complexing agents for separation of some platinum group ions on cellulose ion-exchangers has been investigated. The greatest differences in the affinities of Pd(II) and Pt(IV) toward the cellulose ion-exchangers are obtained in the presence of DPTA, Cellex D (as ion-exchanger) in hydroxide form. The column separation of Pd(II) from Pt(IV), Rh(III) from Pd(II) and of a Rh(III)Pd(II)Pt(IV) mixture can be achieved with DPTA and chloride solutions. The method can be for determination of the components of RhPdPt alloys.     

Direct enantiomeric high performance liquid chromatographic separation of aminoglutethimide and its major metabolite on a series of Chiralcel OD and Chiralcel OJ columns and its application to biological fluids

A direct, isocratic, sensitive and precise liquid chromatographic method is presented for the enantiomeric separation of aminoglutethimide (AG) and its acetylated metabolite (AcAG) using cellulose tris-3,5-dimethyl phenyl carbamate (Chiralcel OD) and cellulose tris(4-methylphenyl benzoate) ester (Chiralcel OJ) columns in series. The enantiomeric elution order is determined by separate chromatography of the racemate AG and racemate AcAG and of their separate enantiomers under similar conditions. This method has been used to determine and identify the enantiomers of AG and AcAG in the urine sample collected from a metastatic breast cancer patient after administration of AG for 24 h. Large amounts of (+)-R-AG are excreted unchanged in the urine together with smaller quantities of (+)-R-AcAG, while most of the (-)-S-AG is metabolically converted into (-)-S-AcAG.     

Dipolar aprotic solvents in thin-layer chromatography of inorganic substances

Summary The potential of dimethyl sulphoxide (DMSO) as a mobile phase for chromatography on ready-for-use, thin-layers of silica gel, cellulose, and alumina has been examined with ferro- and ferricyanide anions, applied alone or as a mixture, as systems to be separated. The most satisfactory results, with very compact spots, are observed with silica gel thin-layers. The behaviour on cellulose layers is similar to that on paper, but the chromatographic spots are more compact in the former case, and therefore the separation there is much cleaner and more rapid. On alumina layers both the anions are highly adsorbed at the point of application, and ferrocyanide is rapidly oxidized to ferricyanide in the presence of DMSO. Alumina layers are therefore unsuitable for chromatography in the present system. The differentiative behaviour of DMSO towards the two closely similar anions is explained by considering the semipolar nature of the S–O bond, the molecular and electronic structure of DMSO, and the difference in ionic volume and ionic charge of the two anions.     

Thin layer chromatography of 57 metal ions on an inorganic ion-exchanger in mixed solvent systems

Summary Thin layers of stannic arsenate have been used to study the chromatographic behaviour of 57 metal ions in different mixed solvents. Au³⁺, Hg²⁺, UO ₂ ²⁺ , Be²⁺ and Al³⁺ and others can be easily separated from numerous metal ions. Fast quaternary, ternary and binary separations have been also achieved. Important separations are discussed. The effect of pH, duration of heating of ionexchanger plates and layer thickness on the R_f values has been studied and discussed. It is shown that Lederer's equation is also obeyed by thin layers of stannic arsenate, if instead of concentration of Na⁺ ion its activity is taken into consideration.     

Hold-up time in gas chromatography. V. Dependence of the retention of n-alkanes on the chromatographic variables in isothermal gas chromatography

The chromatographic behaviour of n-alkanes and other homologous series in isothermal gas chromatography has been shown to depart from the "linear" representation of the logarithms of the adjusted retention times vs. carbon number. One of the expressions proposed to describe this behaviour is tR(z)=A+exp(B+CzD). In this paper, a regression analysis shows that three of the parameters of the equation depend on different chromatographic variables such as hold-up time, average linear gas velocity, volume and polarity of the stationary phase and temperature of the column. The fourth parameter (D), responsible for the departure from the "linearity", does not depend on any chromatographic variable, and represents a gradual decrease of the contribution of the methylene groups to the general properties of n-alkanes, with no relation to the chromatographic phenomenon.     

Identification and Separation of Some Anions on Plain and Mixed Adsorbent Layers Using Water as Eluent

The analytical potential of water as an eluent in thin layer chromatographic separation of various anions on plain adsorbent layers (silica gel "G" alumina, and cellulose) as well as on beds containing different combinations of silica gel, alumina, or cellulose has been investigated. In addition to some important separation of anions, microgram separation of IO⁻₄ from milligram quantities of IO⁻₃, Bro⁻₃, MoO²⁻₄, and Fe (CN)³⁻₆ has been realized. The effect on pH of the sample in the separation of IO⁻₄ from accompanying ions has also been studied. The limits of detection and dilution limits of anions on alumina thin layers have been determined. NO⁻₂ in artificial seawater has been detected. The effect of CaCl₂, MgCl₂, and NaHCO₃ on some ternary separations of analytical importance has been examined.     

Application of radioisotopes in column chromatography on substituted celluloses--II. The separation of gold from silver, iron and other metals

The chromatographic behaviour of several metals has been studied on columns of natural and substituted celluloses, by using radioisotopes. It has been found that gram and nanogram amounts of gold are not adsorbed on natural cellulose, and consequently gold can be separated from nanogram amounts of silver, iron, zinc, cadmium, chromium, manganese and cobalt. Gold has a limited tendency to form complexes with the functional groups of the celluloses, but the other metals mentioned formed very stable complexes. The results have also been compared with those obtained for mercury.