Inside the History of Italian Coloring Industries: An Investigation of ACNA Dyes through a Novel Analytical Protocol for Synthetic Dye Extraction and Characterization

Abstract

The introduction of synthetic dyes completely changed the industrial production and use of colorants for art materials. From the synthesis of the first synthetic dye, mauveine, in 1856 until today, artists have enjoyed a wider range of colors and selection of chemical properties than was ever available before. However, the introduction of synthetic dyes introduced a wider variety and increased the complexity of the chemical structures of marketed dyes. This work looks towards the analysis of synthetically dyed objects in heritage collections, applying an extraction protocol based on the use of ammonia, which is considered favorable for natural anthraquinone dyes but has never before been applied to acid synthetic dyes. This work also presents an innovative cleanup step based on the use of an ion pair dispersive liquid–liquid microextraction for the purification and preconcentration of historical synthetic dyes before analysis. This approach was adapted from food science analysis and is applied to synthetic dyes in heritage science for the first time in this paper. The results showed adequate recovery of analytes and allowed for the ammonia-based extraction method to be applied successfully to 15 samples of suspected azo dyes from the Azienda Coloranti Nazionali e Affini (ACNA) synthetic dye collection, identified through untargeted HPLC-HRMS analyses.

The 20th century and its new colours: Investigating the molecular structures of historical synthetic dyes using Raman spectroscopy

“…When a strong similarity with the reference spectra was observed, chromatographic analysis with mass spectrometry detection was followed, which provided further data. These results will be only mentioned, and they are the object of another paper 57 . The whole set of nomenclature and Raman data, including spectra, is provided for all the standards and sample in Supporting Information.…”

“…These results will be only mentioned, and they are the object of another paper. 57 The whole set of nomenclature and Raman data, including spectra, is provided for all the standards and sample in Supporting Information.…”

“…In this article, the Raman results of the investigation are shown. This represented the only non‐invasive spectroscopic analysis applied to the samples from ACNA, which acts as part of a three‐step protocol involving the above‐mentioned preliminary nomenclature research and confirmatory liquid chromatography 57 as a final micro‐destructive method. The aim is to illustrate the potential of standard Raman spectroscopy for non‐destructive analysis of modern synthetic textile dyes through the successful identification of many of the investigated historical samples in this case study.…”

An Introduction and Recent Advances in the Analytical Study of Early Synthetic Dyes and Organic Pigments in Cultural Heritage

“…It is mixed in an oxalic acid/MeOH/acetone/H 2 O (1:30:30:40, v/v/v/v) solution and is mainly used for mordant dyes and organic lakes [155]; it is also used in a mixture pyridine/H 2 O/1.0 M oxalic acid (45:45:10 v/v/v) [32]. • Ammonia-EDTA treatment of the sample can be followed by an ion pair dispersive liquid-liquid microextraction in chloroform using tetra-n-butylammonium bromide (TBAB) as ion pair reagent and methanol as disperser [156].…”

“…HPLC-DAD has been extensively used for the characterisation of synthetic colourants in archive materials and artworks [5,11,40,62,[171][172][173][174][175][176][177][178][179], whereas HPLC-MS is slightly less common due to the higher cost of the instrument and higher complexity of data interpretation [11,21,32,36,62,80,156,160,[171][172][173][174][180][181][182][183]. On the other hand, the straightforward identification of a compound can be more easily achieved by high-resolution tandem mass spectrometry (HR-MS/MS), whose applications have increased in heritage science in the last decade.…”