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•We optimized a RP-HPLC-DAD-HRMS method suitable for the simultaneous analysis of acid and basic synthetic organic pigments.•We proved that the optimized method can be translated also ...to HRMS detection.•We improved the chromatographic separation of natural and synthetic acid dyes.•We paved an ultra-selective and ultra-sensitive analytical strategy able to minimise peak tailing.•We applied the optimized method to the analysis of a contemporary Persian carpet.
Acid synthetic organic pigments (SOPs), namely water-soluble anionic compounds containing acidic groups (e.g. −SO3H, –NO2, etc), were introduced into artistic materials in the late 19th century. SOPs were often combined in highly complex mixtures to achieve the desired colours, and therefore, chemical analysis requires ultra-selective and ultra-sensitive methods such as reversed-phase liquid chromatography coupled with mass spectrometric detectors. However, acid SOPs produce chromatographic tailing, leading to loss of resolution and sensitivity. To improve their detection, in this work an approach based on liquid chromatography coupled to a diode array detector and high-resolution mass spectrometry (HPLC-DAD-HRMS) was optimized. The study was carried out using standard acid SOPs (Amido naphthol red G, Cotton scarlet, and Naphthol yellow S), also assessing the effect of chromatographic parameter modification on a selection of natural dyes (Carminic acid, Alizarin, and Purpurin) and basic SOPs (Methylene blue and Methyl violet). Starting from a chromatographic gradient optimized for the analysis of tannins in iron gall inks, different flow rates and mobile phase modifier (formic acid) concentration were tested. The chromatographic efficiency (number of theoretical plates, NTP), resolution (R), symmetry factor (SF), ionisation efficiency (IE), signal-to-noise ratio (SNR), limit of detection (LOD) and limit of quantification (LOQ) were evaluated for each analyte. This enabled us to determine the optimal chromatographic conditions for the analysis of acid dye-based artistic materials (gradient with water with 1 % v/v formic acid (FA); acetonitrile with 0.3 % v/v FA; flow rate = 0.6 mL/min). Finally, the optimized method was applied for the investigation of SOP components of a Persian carpet and proved effective in improving both sensitivity and selectivity of the target analytes in a complex matrix. This study not only provides us with a chromatographic method that could be universally valid for the analysis of historical and contemporary artistic materials, but also caters to the difficult chromatographic separation of acid dyes in food, environmental, and forensic chemistry.
The separation, detection and quantitation of specific species contained in a sample in the field of Cultural Heritage requires selective, sensitive and reliable methods. Procedures based on liquid ...chromatography fulfil these requirements and offer a wide range of applicability in terms of analyte types and concentration range. The main applications of High Performance Liquid Chromatography in this field are related to the separation and detection of dyestuffs in archaeological materials and paint samples by reversed-phase liquid chromatography with suitable detectors. The relevant literature will be revised, with particular attention to sample treatment strategies and future developments. Reversed phase chromatography has also recently gained increasing importance in the analysis of lipid binders and lipid materials in archaeological residues: the main advantages and disadvantages of the new approaches will be discussed. Finally, the main applications of ion chromatography and size exclusion chromatography in the field of Cultural Heritage will be revised in this chapter.
The molecular characterization of organic materials in samples from artworks and historical objects traditionally entailed qualitative and quantitative analyses by HPLC and GC. Today innovative ...approaches based on analytical pyrolysis enable samples to be analysed without any chemical pre‐treatment. Pyrolysis, which is often considered as a screening technique, shows previously unexplored potential thanks to recent instrumental developments. Organic materials that are macromolecular in nature, or undergo polymerization upon curing and ageing can now be better investigated. Most constituents of paint layers and archaeological organic substances contain major insoluble and chemically non‐hydrolysable fractions that are inaccessible to GC or HPLC. To date, molecular scientific investigations of the organic constituents of artworks and historical objects have mostly focused on the minor constituents of the sample. This review presents recent advances in the qualitative and semi‐quantitative analyses of organic materials in heritage objects based on analytical pyrolysis coupled with mass spectrometry.
Analytical pyrolysis is experiencing previously unexplored potential, thanks to recent instrumental developments. Recent advances in the heritage field enable the investigation of several organic materials in artistic and historical objects that are macromolecular in nature, or which undergo polymerization upon curing and ageing, by strategies based on analytical pyrolysis coupled with mass spectrometry.
•We applied liquid chromatography-tandem mass spectrometry to the analysis of historical iron gall ink recipes.•We characterised ageing markers of iron gall inks by HPLC-ESI-Q-ToF.•We highlighted ...different degradation trends depending on historical recipes and ageing conditions.•We proved that it is possible to use 15 µg as minimum amount of sample for the HPLC-ESI-Q-ToF analysis of iron gall inks.
Several manuscripts and drawings of our historical and artistic heritage have been produced with iron gall inks. To obtain an iron gall ink, ancient treatises cite the addition of ferrous sulphate and gum Arabic to a decoction of oak galls as a basic procedure. Owing to the development of synthetic chemistry, iron gall ink recipes were improved with new materials and procedures in the late 19th and early 20th century. Notably, many conservation issues arise from the interaction between iron gall inks and the paper support of manuscripts and drawings. To date, most of the research on the topic are focused on paper preservation by non-destructive analytical methods, which provide only limited information on degradation process trends and minor components, representative of iron gall ink's recipes. In the present work, three historical recipes of iron gall inks (alizarine ink, Reid ink, modern gall ink), dated to 19th-20th century and differing for the preparation method and additives, were characterized. The molecular markers of iron gall inks and of gallic acid degradation were detected by an optimized protocol based on high performance liquid chromatography coupled to high resolution mass spectrometry (HPLCHRMS). Furthermore, by performing ageing tests on reference materials in different indoor conditions (natural light and stored in the dark), two degradation mechanisms were observed: hydrolysis of poly-galloyl glucose species and auto-oxidation of gallic acid. Thus, different chemical profiles and ageing trends were revealed depending on the starting recipe. The procedure Limit of Detection (LOD) was estimated, improving the approaches reported so far in the literature. Finally, the strategy was successfully applied for the characterisation of the ink employed in a very degraded 16th century manuscript, granting access to the complete molecular profile of an iron gall ink with just 15 µg of sample.
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Historical and archaeological textiles are among the most crucial and vulnerable records of our social and cultural history. Analysis of organic colorants found in these materials is unquestionably ...one of the most powerful tools to understand historical developments, cultural exchanges, and progress in science and technology. Natural anthraquinones represent the most commonly used natural colorants for textile dyeing until the late 19th century. The identification of anthraquinones in cultural heritage objects is a challenging task due to the small size of historical samples, diversity of potential dye sources, variable extraction procedures and dyeing methods, complex chemical constitution, structurally analogous chromophores, and possible presence of degradation products and contaminants. Developments in dye analysis of historical interest have originated and expanded along with the general advances in analytical science. In the last few decades, a close cooperation between science and cultural heritage disciplines contributed enormously to this field. The topic of historical dyes and their analysis in textiles, artworks, archaeological objects and cultural heritage materials has been reviewed several times in the last fifteen years. However, no review has been published to-date exclusively on the analysis of anthraquinone colorants in historical and archaeological textiles. Overall, liquid chromatography (LC)-based techniques have been the most widely used method for anthraquinone dye analysis. Owing to increasing demand of minimally invasive/non-invasive techniques, recent developments of novel techniques have resulted in the availability of many alternative/complementary methods to LC-based analysis. This review begins with a short overview of sources, chemistry and importance of natural anthraquinone dyes found in historical textiles before turning to a detailed discussion on developments involving established and emerging analytical techniques of anthraquinone dye analysis for textile cultural heritage materials. To illustrate the state-of-the-art, representative examples of analytical techniques highlighting their advantages, limitations and applicability are also presented.
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•Critical review of anthraquinone dye analysis methods for historical textiles highlighting advantages, limitations and applicability.•Aspects of sampling, extraction and analysis are critically discussed.•HPLC-based techniques are still the most widely used.•New trends include minimized sample needs and non-destructive methods.
The study and characterization of organic dyes in textiles, wastewaters, food, cosmetics and forensic specimens is an increasingly important field of research and a challenge for analytical ...chemistry. Sensitive and specific methods are required to determine molecular markers at very low concentrations and to detect and identify their relative degradation products. In this field, the present paper deals with the development of an extremely sensitive analytical strategy able to identify synthetic organic dyes even after ageing, such as photo-oxidation resulting in severe fading, by identifying specific stable markers. Rhodamine B (C.I. 45,170), belonging to the class of xanthenes, was chosen as representative of fugitive dyes of high commercial and historical importance, in the frame of a research promoted by the European platform IPERION-CH. The behaviour of Rhodamine B used as a dyestuff for wool yarns, subjected to accelerated photo-ageing, was investigated by chromatographic, spectroscopic and high resolution mass spectrometric techniques. The ultra-sensitive analytical method developed, based on core shell reverse phase analytical column separation, allowed us to characterize Rhodamine B oxidation products investigating their mass fragmentation and rationalizing the resulting ageing pathway. These degradation compounds, characterized in artificially aged reference wool yarns, confirmed to be valuable markers for the identification of Rhodamine B even in a complex historical textile matrix as a red Florentine velvet cope subjected to restoration in the 20th century.
•Development of an ultra-sensitive HPLC-DAD-FD and HPLCMS method for the analysis of Rhodamine B and its degradation products•Study of the photo-ageing process of Rhodamine B in artificially aged reference wool yarns and in an historical velvet cope•Characterization of the intermediates of Rhodamine B fading•Outline of the degradation process on the base of the concentration trend of the different identified compounds in relation to accelerated ageing time
We propose a new analytical method using reverse phase High performance liquid chromatography (HPLC) coupled through an electrospray source with a tandem quadrupole-time-of-flight (ESI-Q-ToF) mass ...spectrometric detector for the full characterization and quantitation of the different classes of fatty acids and acylglycerols in lipid samples in a single chromatographic run. In this work, we optimized the derivatization reaction for free fatty acids with 2-hydrazinoquinoline, which is a low-cost approach, using a full factorial design. This reaction does not involve transesterification, thus enabling the free fatty acids to be separated and successfully quantified in the presence of mono-, di- and triacylglycerols without altering the whole glyceride profile. This new analytical method provides a full profile of fatty acids, mono-, di- and triglycerides within a relatively short chromatographic run (less than 40 min), with low operating back-pressure (less than 110 bar). The derivatization of the free fatty acids allows their detection in positive mode, with limits of detection in the range of 0.2–1.9 ng/g, and a dynamic range of two orders of magnitude. The figures of merit of the procedure are competitive with respect to the literature.
The method was validated by characterizing two different types of olive oils. Free fatty acid content was quantified, and the results are consistent with literature data. The method was applied to the characterization of cow milk and an infant formula, after the precipitation of proteins and phospholipids, and proved suitable for the detection of short chain fatty acids, free fatty acids and glycerides highlighting differences in the composition of the two milks.
The proposed procedure improves the current methods for the analysis of acylglyceride based materials, such as olive oil, and proved promising for the characterization of lipids in complex matrices, such as milk.
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•A derivatization procedure for fatty acids (FFAs) with 2-hydrazinoquinoline is proposed.•The HPLC-MS procedure detects FFAs and acylglycerides in a single chromatographic run.•The procedure displays outstanding performances in terms of LOD and LDR.•The validation of the procedure through the analysis of oil samples is successful.•The application to the characterization of milk samples is promising.
The biological electron transfer reactions play an important role in the bioactivity of drugs; thus, the knowledge of their electrochemical behavior is crucial. The formation of radicals during ...oxidation or reduction, the presence of short-living intermediates, the determination of reaction mechanisms involving electron and proton transfers, all contribute to the comprehension of drug activities and the determination of their mode of action and their metabolites. In addition, if a drug is encapsulated in the cyclodextrin cavity, its electrochemical properties can change compared to a free drug molecule. Here we describe the combination of cyclic voltammetry, UV-Vis spectroelectrochemistry, GC-MS, HPLC-DAD, and HPLC-MS/MS as techniques for evaluating the oxidation mechanism of a drug encapsulated in the cavity of a cyclodextrin. The cavity of cyclodextrin plays a significant role in increasing the stability of the encapsulated products; therefore the identification of oxidation intermediates as semiquinone and benzofuranone derivatives of quercetin is possible in these conditions. The differences in oxidation potentials of the bioactive flavonol quercetin and its cyclodextrin complex relating to its antioxidant activity and the oxidation mechanism are herein discussed.
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