Marek Ślebioda

Dynamic ligand-exchange chiral stationary phases derived from N-substituted (S)-phenylglycinol selectors

Abstract Six chiral stationary phases based on N-substituted ( S -phenylglycinol were synthesised and dynamically loaded onto octadecyl-silica gel column. The effect of the alkyl (C 7 , C 9 , C 12 ) and aryl (methoxybenzyl, naphtylmethyl, anthrylmethyl) anchor moieties and influence of various chromatographic conditions (concentration of copper(II) ions, pH of the mobile phase, column temperature and organic modifier addition) on retention and enantioselectivity of the chiral columns toward selected α-amino acids were studied. The surface concentrations of chiral selectors, determined using the breakthrough method, were found to be in the range of 0.66–0.88 μmol/m 2 . The order of elution of α-amino acid enantiomers was found to be R S on the N-C 12 -( S )-phenylglycinol and all N-aryl-( S )-phenylglycinol phases but a reversed elution order ( S R ) was observed on the N-C 7 - and N-C 9 -( S )-phenylglycinol phases.

Polycyclic aromatic hydrocarbons as test probes to investigate the retention behavior of 1,3-alternate calix[4]arene silica-bonded stationary phases

A series of polycyclic aromatic hydrocarbons (PAHs) of different size and shape has been used to characterize the chromatographic behavior of five calix[4]arene stationary phases in 1,3-alternate conformation synthesized in our laboratory. The selection of linear, four-ring nonlinear, and five-ring PAHs gave data on selectivity changes across range of the calix[4]arene columns. Retention of the 12 aromatic solutes has been evaluated at various methanol contents in the mobile phase (70-100% v/v) and column temperatures (20-45°C). The thermodynamic parameters underlying the retention mechanisms revealed that each of the five calix[4]arene columns exhibited variation in selectivity and retention of PAHs caused by enthalpy and entropy effects. The calixarene stationary phases substituted with electron-withdrawing groups exhibit enhanced selectivity toward PAHs in comparison to the rest of the investigated columns. The observed divergences are due to differences in solute-stationary phase interactions and originate in π-π and π-electron transfer specific to the analytes and the type of calix[4]arene functionalization at the upper rim, as well as steric and sorption phenomena.

Substituent effect in reaction of dicyclohexylcarbodiimide with substituted benzoic acids

Abstract A curved Hammett relationship was observed for the reaction of substituted benzoic acids with dicyclohexylcarbodiimide in buffered solution. The reaction is promoted by electon-withdrawing substituents because of larger concentration of the acid anion present in the reaction mixture. On the other hand, electron-donating substituents encourage nucleophilic attack of the acid anion on the protonated carbodiimide.

Identification and characterization of the Indian Yellow dyestuff and its degradation products in historical oil paint tube by liquid chromatography mass spectrometry

An analytical protocol for identification of dyes using reversed phase liquid chromatography-mass spectrometry with atmospheric pressure electrospray ionization (LC-ESI/MS) is presented. The developed method has been successfully applied in identification of euxanthic acid and euxanthone, the main components of the Indian Yellow dye in a historical oil paint tube produced by Richard Aines, a recognizable French company supplying art materials. The paint tube from which the sample has been taken belonged to a famous Polish painter from the 19th century – Jan Matejko. Various methods of extraction of the Indian Yellow dyestuff from the oil paint were systematically investigated. Efficiencies of the nine extraction procedures (based respectively on use of: HCl, HF, acetylacetone, and formic, tartaric, oxalic, trifluoroacetic and citric acids) were compared on the basis of euxanthic acid to euxanthone chromatographic peak areas ratio. It was found that use of HF, acetylacetone and the organic acids ensures a non-destructive recovery of intact acid-labile components, while the strong HCl mineral acid not only allowed extraction of the colorant from the binding medium, but also decomposes the glycosidic dye into the parent aglycon and causes a formation of methyl euxanthonate and numerous products which may hinder the proper identification of the dye. The Indian Yellow was fully characterized with the use of spectrochromatographic techniques for the first time. The fragmentation pathways of the identified colorant ions and their degradation products were proposed.

A multi-analytical approach to the characterization of natural organic dyestuffs and inorganic substrates present in the 19th-century artistic oil paints manufactured by a French art materials supplier Richard Ainès

This paper presents a comprehensive analysis of artistic paints produced in the 19th century by a French art materials supplier Richard Aines. Improved mild extraction with hydrofluoric acid enabled the observation of intact organic dyes. Reversed-phase liquid chromatography with diode-array and mass spectrometry detection was utilised for the identification of 35 dyes present in yellow and red paint samples, and in selected plant extracts. The developed analytical method allowed more efficient separation of several isomeric flavonoid and anthraquinone dye components of the paint samples. Persian berries and weld were identified as the dye sources in the yellow paint samples. The red oil paint had been coloured with the madder lake-type plant. Studies of dye extracts of the historical samples show the presence of uncommon dye components (quercetin-O-rhamnoside-glucuronide and rhamnasin-O-rhamnoside-glucoside) that could enhance this identification. The paint samples were additionally analyzed by X-ray fluorescence (XRF) and scanning electron microscopy with energy dispersive X-ray analysis (SEM-EDX). Aluminum, Sn, Zn, Ca, Cu, S, Si, and K were detected confirming the presence of aluminium hydrate and tin salts as carriers, as well as chalk, and other components used during the production of these paints. The SEM with the BSE detector images revealed the homogenous texture of finely ground lake pigments.

Chromatographic determination of citric acid for monitoring the mould process

Abstract A reliable method for monitoring the mould citric acid production process is presented. The method is based on in-line sample work-up and high-performance liquid chromatographic determination of citric acid with ultraviolet detection. It provides good precision (better than 1% in the range of 0–150 g dm −3 ) and requires no special equipment.

Chromatographic and Spectroscopic Identification and Recognition of Natural Dyes, Uncommon Dyestuff Components, and Mordants: Case Study of a 16th Century Carpet with Chintamani Motifs

A multi-tool analytical practice was used for the characterisation of a 16th century carpet manufactured in Cairo. A mild extraction method with hydrofluoric acid has been evaluated in order to isolate intact flavonoids and their glycosides, anthraquinones, tannins, and indigoids from fibre samples. High-performance liquid chromatography coupled to spectroscopic and mass spectrometric detectors was used for the identification of possible marker compounds with special attention paid to natural dyes present in the historical samples. Weld, young fustic, and soluble redwood dye were identified as the dye sources in yellow thread samples. Based on the developed method, it was possible to establish that red fibres were coloured with lac dye, whereas green fibre shades were obtained with indigo and weld. Tannin-containing plant material in combination with indigo and weld were used to obtain the brown hue of the thread. Hyphenation of high-performance liquid chromatography (HPLC) with quadrupole time-of-flight mass spectrometry (QTOF MS) and triple-quadrupole mass spectrometry (QqQ MS) enabled us to recognise four uncommon and thus-far unknown dye components that were also found in the historical samples. These compounds probably represent a unique fingerprint of dyed threads manufactured in a Turkish workshop. Scanning electron microscopy with energy-dispersive X-ray detector (SEM-EDS) and Fourier transform infrared spectroscopy (FT-IR) were used for the identification and characterisation of substrates and mordants present in the historical carpet. Carbon and oxygen were detected in large quantities as a part of the wool protein. The presence of aluminium, iron, and calcium indicated their usage as mordants. Trace amounts of copper, silica, and magnesium might originate from the contaminants. FT-IR analysis showed bands characteristic for woollen fibres and SEM micrographs defined the structure of the wool.

Application of polarimetric detector for the high-performance liquid chromatographic determination of the optical purity of 5(4H)-oxazolones

An HPLC procedure for monitoring one of the reactive intermediates in peptide synthesis, 5(4H)-oxazolone, was developed. The reversed-phase mode made it possible not only to monitor the formation and consumption of oxazolone, but also to determine the concentration of other components of the reaction mixture. Moreover, with polarimewtric and UV detectors coupled in series it was possible to determine the content of both oxazolone enantiomers in the reaction mixture. Hence with the achiral chromatographic system employed, the enantiomeric excess of the crucial component of the mixture could be monitored.

Simple and precise high-performance liquid chromatographic method for the investigation of carbodiimide-mediated peptide synthesis

A simple HPLC method for the determination of intermediates, products and by-products of peptide synthesis is described. The mean errors of the quantitative determination of all components of the reaction mixture at any stage of peptide synthesis were found to be low (1.3–2.1%). The sensitivity was good enough to detect a 0.05% yield of the products. The method was successfully used to determine the effects of the reaction conditions on optical purity and yield of the synthesised peptide and amino acid derivatives.