Chromatography on Papers Impregnated with Zinc Silicate: A New Adsorbent for Qualitative and Quantitative Separation of Amines

Abstract

Papers impregnated with zinc silicate have been used for the chromatographic studies of amines taken in the form of their hydrochlorides. R_f values of various amines have been determined and compared with its behaviour on plain papers. Quantitative separations of dimethylamine from methylamine, α-naphthylamine, o-toluidine and o-nitroaniline; o-phenylenediamine from m-phenylenediamine; diphenylamine from piperidine have also been achieved on columns loaded with zinc silicate exchanger.     

Zinc Silicate as a New Adsorbent for Paper Chromatographic Separation of Phenols

Abstract

A new adsorbent zinc silicate has been used for the paper chromatographic separations of different phenols. R_F values have been determined and compared with those obtained on plain papers. A new term R_i has been calculated for various phenols. The dependance of R_i and R_F on various factors have also been studied and discussed.     

Iron(III) Diethanolamine as a Ne Adsorbent for Chromatographic Separations of Phenols

Abstract

A new adsorbent iron(III) diethanol amine has been utilized for the chromatographic separations of phenols. R_F values of 31 phenols in ethanol and ammonia solution of four different concentrations have been studied. On the basis of difference in R_F values various analytically important qualitative separations of phenols on impregnated papers and quantitative separations on columns of iron(III) diethanolamine have been achieved.     

Thin-layer chromatographic separation and identification of some anions on copper sulphate impregnated silica gel layers

Summary Thin-layer chromatographic behaviour of thirteen anions on plain silica gel and silica gel impregnated with copper sulphate solution has been investigated in aqueous-organic solvents containing acetone, some of which have achieved reliable and reproducible separations. The effect of copper sulphate concentration on the mobility of anions has been examined. The results obtained on plain silica gel have been compared with those obtained on copper sulphate impregnated layers. The impregnated layers dramatically change the selectivity and permit separations not possible on untreated silica. Aqueous sodium chloride-acetone (9∶1) and ammonium hydroxide-acetone (9∶1) were the most effective solvent systems for differential migration of anions. Better results in terms of clarity of detection and compactness of spots were found with HCOOH-acetone as compared to HCl-acetone. The effect of anion loading on R_F values has been investigated and identification limits on impregnated layers determined.     

Metal Ion Chelation Chromatography on Complexon Sorbed Stannic Silicate

Abstract

Stannic silicate has been sorbed with complexones like xylenol orange, eriochrome black T and 1,10-phenanthroline for use as a chelate ion exchanger. The sorption capacity for different metals has been worked out. Kd values have been determined. Xylenol orange was used for the separation of Th(IV) from Cd(II) and Zn(II) and Cu(II) from Cd(II) and Zn(II), 1,10 phenanthroline for the separation of Fe(II) from Fe(III). These separations are based on the stabilities of the various complexes formed by the interaction of metal inns with complexones. By elution of metal ions which forms less stable complexes with the complexones no evidence of complexing agent in the eluate was found.     

Chromatographic behaviour of metal ions on tin(IV) and titanium(IV) antimonate papers

Summary The chromatographic behaviour of 49 metal ions has been studied on papers impregnated with Sn(IV) and Ti(IV) antimonates in aqueous HNO₃ and mixed solvent systems containing dimethyl sulphoxide. Numerous separations have been achieved and the Alberti equation, for Sn(IV) and Ti(IV) antimonate papers, in the modified form: –nloga K⁺=R_M + constant (a K⁺=activity of K⁺), has been verified. The effect of the concentration of impregnating reagents on these papers has been determined and compared with other papers. The effect of pH on R_f, R_i, log R_f and R_M values of metal ions has also been examined in aqueous systems.     

Ligand Exchange Chromatography Separations of Some Phenolic Compounds on Zinc Silicate in Fe(III) Form

Abstract

The high sorption capacity of zinc silicato for Fe(III) has been utilized for the separation of phenolic compounds on the basis of ligand exchange. The coordination of ligands with the central metal ion occurs through oxygen. Ligand sorption capacity, rate of sorption and break-through capacity have been studied. The distribution coefficients (Kd values) of 21 phenols have been determined in five different systems. Selectivity has been determined on the basis of Kd values of these phenols. On the basis of differences in Kd values various analytically important quantitative binary and ternary separations on columns of zinc silicate in Fe(III) form have been achieved.     

Thin-Layer Chromatography of Some Monothio-β-Diketonate Complexes of Nickel,Zinc and Cobalt

Abstract

A silica gel adsorbent has been successfully used to separate three series of nickel, zinc and cobalt complexes of 1,1-difluoro-4-mercapto-4-(2′-thienyl)but-3-en-2-one, 1,1,1-trifluoro-4-mercapto-4-(2′-thienyl)but-3-en-2-one, 1,1,1-trifluoro-4-mercapto-2-(2′-naphthyl)but-3-en-2-one. For comparative purposes R_F data for the protonated ligands are also included. The ZnL₂ complexes gave R_F values in single and binary solvent systems which were similiar to the R_F values of the ligands; whereas, the NiL₂ and CoL₃ complexes gave R_F values which paralled each other in most solvents.     

Separation Studies of Metal Ions in Sodium Thioglycolate Medium by Thin Layer Partition Chromatography

Abstract

A thin layer partition chromatographic method has been developed for separation of Fe(III), Ni(II), Zn(II), Cu(II), Pb(II) and Mn(II) on thin layers of silica gel-G as an adsorbent. The R_f values were determined using 0.01–0.2 aqueous solution of sodium thioglycolate as a mobile phase. The dependence of R_f values on the migration time, pH and concentration of mobile phase has been studied. The optimum conditions for possible 3-component separation have been determined. Metal ions have been separated, detected, eluted and quantitatively determined by atomic absorption spectroscopy. The present method was applied to the separation and determination of zinc in forensic samples.     

The chromatography of a number of metals on cellulose phosphate layers in sulfuric acid and ammonium sulfate media

Summary The thin-layer chromatographic behavior of 58 metals on an intermediately acidic cation exchanger, cellulose phosphate (P-cellulose), has been surveyed systematically in sulfuric acid and ammonium sulfate media (0.01–2.0 M). The R_f values for many bivalent and univalent metal ions on P-cellulose plates increase with increasing concentration of sulfate ions. Howerver, manganese (II), arsenic (III) and selenium (IV) are not adsorbed on the cellulose to any great extent. Beryllium (II) and other metals, which form either strong phosphate complexes or insoluble sulfate precipitates, are strongly retained on the P-cellulose. The thin-layer chromatographic separations of various metal ions of analytical interest were accomplished to demonstrate the use of R_f measurements for predicting separations in the acid and the sulfate media.     

Synthesis, electrochemistry and metal binding properties of monosubstituted ferrocenoyl peptides with thioether-containing sidechains

Ferrocenoyl peptides incorporating thioether functionality respond more strongly to mercury(II) than to other heavy metal ions in solution. Compounds reported previously in this context are all 1,1′-disubstituted, and all include two or more sulfur-containing amino acids. To test whether two thioether groups are required for effective mercury binding by these systems, we have prepared a series of singly-substituted ferrocenoyl peptides from ferrocenecarboxylic acid and l-methionine, S-methyl-l-cysteine or S-trityl-l-cysteine, and tested them as electrochemical probes for mercury(II). Nine ferrocenoyl peptides have been synthesised using a Boc-protecting group strategy and HBTU-mediated peptide coupling. The electrochemical properties of these compounds have been determined using cyclic voltammetry, and all show fully reversible one electron oxidation steps. Forward sweep half wave peaks (E_F), reverse sweep half wave peaks (E_R), peak separations (ΔE_P) and half wave potentials (E_1/2) are reported. Changes in the potential of the iron(II)/iron(III) redox couple of the ferrocene core have been used to quantify heavy metal-peptide interactions, revealing that these monotopic systems also respond more strongly to mercury(II) than to zinc(II), cadmium(II), silver(I) and lead(II). NMR experiments to characterise the peptide-mercury interaction implicate the thioether sulfur as the site of mercury binding and indicate 1:1 stoichiometry. The crystal structure of ferrocenoyl-S-methyl-l-cysteine methyl ester is also reported. The greater responsiveness of these systems to mercury(II) makes them interesting leads for the development of biologically inspired sensors for this toxic heavy metal.     

A simple molecular model of adsorption chromatography XIV. RF or RM? Secondary retention effects in thin-layer chromatography

Summary It is demonstrated that although the R_F values are directly related to the separations obtained, the R_M values are more convenient in the theory of optimization of chromatograpohic systems. Graphs for direct plotting of R_F values in the R_M scale are shown in both logarithmic and linear solvent composition scale. The effects of preadsorption of the solvent vapours and of simultaneous partition betwen the mobile and the stagnant developing solvent on the retention vs. compostion plots are illustrated. Examples are shown for crossing retentions vs. solvent composition plots.Part XIII: ref [1].     

Organic acid solutions in the chromatography of inorganic ions

Summary We present a study of the chromatographic behaviour of sixty ions on thin layers of cellulose, employing as eluents aqueous solutions of tartrate, at various molarities (from 0.1 to 1.0 mol dm^–3 and pH values (from 2.0 to 10.0 obtained with aqueous ammonia). The ions migrate, whether they are complexed with the tartrate or not, with high R_F values and are not influenced by variation of the tartrate concentration. The pH variations, owing to the formation of partial hydrolysis or precipitation products or possibly ammonia complexes, have a greater effect on the rate of ion migration and cause a decrease in the R_F values. We show interesting separations obtained with these eluents.This work has been in part supported by C.N.R. of Italy     

Chromatographic studies of some cephalosporins on thin layers of silica gel G–zinc ferrocyanide

A simple, selective and precise thin‐layer chromatographic method has been developed for the analysis of eight cephalosporin antibiotics, namely cephadroxil, cephalexin, cefixime, cefaclor, cefpodoxime proxetil, cefuroxime axetil, cefotaxime sodium and ceftriaxone sodium. The hR_F values of these cephalosporins were investigated on silica gel G–zinc ferrocyanide layers. Mixing of zinc ferrocyanide with silica gel G resulted in a decrease in hR_F values, removal of tailing and better resolutions. The influence of silica gel G–zinc ferrocyanide ratio and mobile phases on the chromatographic behavior of cephalosporins on thin layers was investigated. Cephalosporins were selectively separated in their binary and ternary synthetic mixtures and pharmaceutical formulations. Quantitative separations of cephalosporins from their synthetic mixtures were also achieved with good recoveries (97.8–100.3%). Copyright © 2010 John Wiley & Sons, Ltd.     

Paper chromatography of inorganic cations part II

The R_F values of some metals were measured in ethyl isopropyl butyl, and amyl alcohols containing hydrochloric acid.The R_F value increase in most cases with a decrease in the number of carbon atoms of the alcohol. Specific separations were obtained for thallium and zirconium.     

Anion-exchange behaviour of a number of metal ions on DEAE-cellulose in hydrobromic and hydriodic acid media

Summary The adsorption behaviour of 48 metal ions on DEAE-cellulose layers has been investigated in aqueous hydrobromic and hydriodic acid media. R_F values are given as a function of the hydrobromic and hydriodic acid concentration over the ranges 0.01–6 mol dm^–3 and 0.01–3 mol dm^–3, respectively, and are compared with those obtained with Avicel SF. R_F spectra are comparatively simple in both media, reflecting the strong affinity of the bromide and iodide ions to the DEAE-cellulose phase. Pd, Pt, Re, Au and Hg are distributed chromatographically in either system, while most other metal ions exhibit rather extreme R_F values of near unity or zero. Therefore, the selectivity of the systems is particularly high for Pd, Pt, Re, Au and Hg, providing the possibility of their excellent selective separations.     

The chromatographic examination of metallic ions,I

Using as solvent, butanol saturated with aqueous solutions of various organic acids, the R_F values of a number of metal ions have been determined by paper partition chromatography. The results obtained may be applied to the qualitative separation of some cation mixtures and the possibility of quantitative separations is indicated in some cases.     

The lipophilicity of parabens estimated on reverse phases chemically bonded and oil‐impregnated plates and calculated using different computation methods

The chromatographic behaviour of the parabens has been investigated on RP‐18F_254S, RP‐18WF_254S, CNF_254S, Diol F_254s and silica gel 60F₂₅₄ plates impregnated with different oils (paraffin, olive, sunflower and corn) using methanol–water mixtures in different volume proportions as mobile phases, the regression determination coefficients being excellent (higher than 0.98 for the majority of compounds). Moreover, highly significant correlations were obtained between different experimental indices of lipophilicity (R_M0, b and scores corresponding to the first principal component (PC1)) and computed log P values. All types of stationary phases investigated appear to be highly suited for estimating the lipophilicity of the parabens.     

Resolution of PTH-amino Acids in Three New Solvents on Zn,Cd, Hg Impregnated Silica Plates

Abstract

A ten component mixture of PTH-amino acids has been resolved by TLC using impregnated silica plates. Three new solvent systems, CHCl₃ -H₂O-EtOAc(28:1:1), CCl₄-AcOH(19:1) and CHC₃-MeOH-Benzene(19:1:5) were developed and used. The effect of 0.1, 0.2 and 0.5 % concentrations of each of the impregnant (Zn⁺⁺, Cd⁺⁺, Hg⁺⁺ ions) on R_F values was studied.     

Synthesis and Chemistry of Novel Perhalogenated Imines,Oxaziridines, and Oxazolidines

Imines have been prepared using three different methods. The thermal addition of tetrafluoroethylene to N‐bromoperhalo‐1‐alkanimines (R_fCF=NBr) to give imines of the type R_fCF=NCF₂CF₂Br, the Lewis acid cleavage of perfluorinated amines to give imines of the type R_fN=CFR_f′ and the one pot reaction between hexafluoroacetone and perfluoroamides. Reactions of these imines with m‐chloroperoxy benzoic acid (MCPBA) lead to the corresponding cis‐perfluoro‐2, 3‐dialkyloxaziridines R_f R_F′. The oxaziridines undergo cycloadditions with olefins to give the corresponding oxazolidines. A preliminary investigation was done on the synthesis and reaction chemistry of complex formed between activated zinc and the 4‐iodo and 4‐bromo‐perhalooxazolidines.