Núria Ferrer

Fourier Transform Infrared Spectroscopy Applied to the Characterisation of 17th-20th Century Calcographic and Xylographic Inks

Abstract The aim of this paper is to optimize the analytical method for the characterisation of 17th–20th century calcographic and xylographic inks. It is very important to use not only non destructive techniques, but also analytical instruments that require a minimal amount of material so as to analyze unique or valuable samples, and simultaneously to obtain as much information as possible about their composition. This study compares different ways of sample preparation for further analysis by Fourier transform infrared spectroscopy. It has been possible to analyze the most important absorptions that appear in the spectra and therefore to associate them with the compounds contained in inks. Some of the compounds identified are: hydroxyapatite (calcium phosphate), Prussian blue (ferric ferrocyanide), linseed oil, carbonates, nitrates and sulfates.

Determination of caffeine in solid pharmaceutical samples by FTIR spectroscopy

Fourier transform infrared spectroscopy has been used for the quantitative determination of caffeine in several pharmaceutical products: acetyl salicylic acid, paracetamol and propyphenazone. The method is simple, rapid and selective, and allows the determination of caffeine without sample pretreatment and without separation from the matrix. Two techniques for measuring the infrared spectra of caffeine are described: transmission through pellets and diffuse reflectance from powder (DRIFT). In both methods, samples were diluted (1%) with KBr. Caffeine in pharmaceutical matrices was recovered within 5% error in pellets and 10% by DRIFT. Relative standard deviations were generally ⩽1.5% for repeated measurements on a single pellet and ⩽ 5% for measurements on different pellets. DRIFT in the vacuum mode gave rather large RSDs. The limit of detection of the pellet technique was about 0.5% caffeine in the original sample.

Analysis of Sediments on Iron Gall Inks in Manuscripts / Analyse von Ablagerungen auf Eisengallustinten in historischen Manuskripten / Analyse de sédiments sur les encres ferro-galliques dans les manuscrits anciens

Abstract Fourier transform infrared (FTIR) is an efficient tool to analyse deposits on iron gall inscriptions that appear on historic documents. Deposits look like white powder or whitish crystals under a microscope. Crystals show cubic or needle shapes with sizes below 20 μm. Mapping infrared spectroscopy in addition allows the selective identification of mixed deposits. Selective analysis of different inorganic oxalates is possible in four regions of the mid-infrared spectrum, thus avoiding interferences with bands of other compounds present. Calcium, potassium and iron oxalates, further calcium sulphate, calcium carbonate, basic iron sulphates and iron ammonium sulphate were identified on samples taken from selected manuscripts. The results enabled to establish a correlation of ink composition and the observed intensity of ink corrosion. Zusammenfassung Eisengallustinten in historischen Dokumenten weisen haufig kristalline, aber auch nicht-kristalline Ablagerungen auf. Sie haben vielfach ein puderiges Erscheinungsbild, oder es handelt sich um weise Kristalle. Diese Ablagerungen lassen sich mit Fourier Transform Infrarotspektroskopie (FTIR) analysieren. Kristalline Ablagerungen haben eine kubische oder nadelige Morphologie bei einer Grose von weniger als 20 μm. Die angewendete Untersuchungstechnik gestattet die getrennte Identifizierung mehrerer Komponenten in den Einlagerungen. Unterschiedliche anorganische Oxalatverbindungen konnten in vier Bereichen des mittleren IR-Spektrums identifiziert werden, wobei Interferenzen mit den Banden zusatzlicher Komponenten ausgeschlossen werden konnten. Bei den identifizierten Verbindungen handelt es sich um Calcium-, Kalium- und Eisenoxalate, auserdem wurden Calciumsulfat, Calciumcarbonat, basische Eisensulfate und Eisenammoniumsulfat in Proben identifiziert, die ausgewahlten Manuskripten entnommen wurden. die erhaltenen Resultate ermoglichten eine Korrelation der Tintenzusammensetzung mit der beobachteten Schadwirkung durch die Eisengallustinten auf die Tragermaterialien. Résumé La spectroscopie infrarouge de Fourier (FTIR) est un moyen efficace pour analyser les dépôts sur les inscriptions a l’encre ferro-gallique qui apparaissent sur les documents historiques. Ces dépôts ont souvent une apparence de poudre blanche ou de cristaux blanchâtres lorsqu’on les étudie au microscope. Les dépôts cristallins ont souvent une morphologie cubique ou se présentent sous forme d’aiguilles avec une taille inférieure à 20 microns. La technique d’analyse utilisée permet d’identifier une sélection de différents composants dans les sédiments déposés. Différentes combinaisons anorganiques oxalates ont pu être identifiées dans quatre régions du spectre infrarouge moyen tout en excluant les interférences possibles avec les bandes d’autres composants. Parmi les combinaisons identifiées trouvées dans les manuscrits sélectionnés il s’agit d’oxalate de calcium, de kalium et de fer ; par ailleurs on a pu identifier aussi dans des échantillons du sulfate de calcium, du carbonate de calcium, des sulfates de fer basiques et du sulfate d’amonium de fer. Les résultats obtenus permettent d’établir une corrélation entre la composition de l’encre et les effets dommageables observes sur les documents comportant de l’encre ferro-gallique.

Quantitative analysis of caffeine applied to pharmaceutical industry

Abstract The direct determination of some compounds like caffeine in pharmaceutical samples without sample pretreatment and without the separation of these compounds from the matrix (acetyl salicylic acid, paracetamol,…) is very worthwhile. It enables analysis to be performed quickly and without the problems associated with sample manipulation. The samples were diluted directly in KBr powder. We used both diffuse reflectance (DRIFT) and transmission techniques in order to measure the intensity of the peaks of the caffeine in the pharmaceutical matrix. Limits of detection, determination, relative standard deviation and recovery using caffeine in the same matrix as in the pharmaceutical product are related. Two methods for the quantification of caffeine were used: calibration line and standard addition techniques.

Quantitative Analysis of Alkylbenzenesulphonates in Water Solution by ATR/FT-IR Spectroscopy

Fourier-transform infrared spectroscopy has been used for the determination of dodecylbenzenesulphonate in commercial samples of liquid detergents. Analyses have been performed without sample treatment. Attenuated total reflectance with use of a ZnSe crystal allows measurement of the bands of the detergent together with the water spectrum. The precision, recovery and accuracy obtained by use of calibration line and standard additions have been optimized.

Quantification of dodecylbenzenesulfonate and tripolyphosphates in solid commercial samples of detergents

Abstract Fourier transform infrared spectroscopy has been used for the quantitative determination of dodecylbenzenesulfonate and tripolyphosphate in solid commercial samples of detergents. The only sample treatment consisted of a separation with ethanol. Dodecylbenzenesulfonate was dissolved and tripolyphosphate remained in the insoluble fraction. The method consisted of transmission measurements of KBr pellets. Precision, recovery and determination using both calibration line and standard addition have been optimized. The determination of dodecylbenzenesulfonate has been compared with the UV method.

FT-IR Spectroscopy and Microscopy with a Diamond Cell Applied to Forensic and Industrial Samples

Fourier-transform infrared spectroscopy, using the diamond cell technique, has been shown to be a useful tool for the analysis of small samples. The diamond cell can be used both in an infrared microscope and in a microbeam compartment. In our laboratory both techniques have been applied to forensic and industrial analysis and some examples are reported. Sample preparation normally consists of physical separation with the help of tungsten needles, microtoming techniques after embedding the samples in paraffin blocks, or the use of solvents to extract some compounds before evaporation on different kinds of plate. The diamond cell technique seems to provide good results for all samples analysed.