Ruth Ann Armitage

Direct Identification of Dyes in Textiles by Direct Analysis in Real Time-Time of Flight Mass Spectrometry

We present here a method requiring no sample preparation for direct identification of the organic dye compounds quercetin, indigotin, and alizarin in reference materials, in solution, and also in situ in dyed fibers by use of direct analysis in real time (DART) ionization and high-resolution time-of-flight mass spectrometry. Exact mass determinations on small samples of dyed textiles were completed in less than 1 min. With the ability to identify flavonoid, indigoid, and anthraquinone classes of dyes, this technique shows early promise as an additional analytical tool in the challenging analysis of organic dyes in rare cultural heritage materials and possesses the unique advantages of sensitivity and simplicity without the preparatory procedures required by other methods.

Mass Spectrometric Radiocarbon Dates from Three Rock Paintings of Known Age

Radiocarbon age determinations are presented on three hieroglyphic texts from Naj Tunich cave in Guatemala containing Maya calendar dates. The ages obtained are on average 110–140 years older than the calendar dates. Several possible reasons are discussed for this discrepancy: one that is applicable to all radiocarbon dates on charcoal, one that applies to rock paintings, and one that is specific for the tropics. Possible problems with the ages ascribed to the Maya calendar dates are also discussed. Even with the potential problems that may exist, these dates still fall within 110–140 years of the ascribed calendar dates. Caution is urged in the interpretation of dates on charcoal pigments from rock paintings; consideration of the “old wood” and “old charcoal” factors is important.

Rock-art image in Fern Cave, Lava Beds National Monument, California: not the AD 1054 (Crab Nebula) supernova

The visual manifestation of the recent Hale-Bopp comet reminds us how telling are those rare objects which suddenly flare in the sky. One can suppose ancient people living by natural light were more compellingly struck by the sight of comets and supernovae, and understandably researchers seek images of them in the shapes of rock-art motifs. An absolute dating contradicts that supposition in respect of a presumed image of the visible supernova of AD 1054.

Cueva La Conga: First Karst Cave Archaeology in Nicaragua

limestone cave in karst formation that has not only numerous pictographs in ochre and charcoal paints, but also four culturally modified natural limestone formations, called speleothems, two of which are carved and two, painted.1 Radiocarbon analyses on five charcoal samples have produced the first dates for pictographs and, indeed, the first radiocarbon dates for northern Nicaragua, which range from cal A.D. 680–905 to cal A.D. 1440–1520. The greatest intensity of painting seems to have occurred in the earlier period. Other physical data and images provide some social information about the ancient people who utilized the cave in a region about which virtually nothing else is known archaeologically. Whereas prehistoric ritual cave use, involving paintings and modified speleothems, has been widely reported in karst regions in Mesoamerica, Cueva la Conga extends southward the known distribution of sites representing ritual use of underground caverns. It is the farthest south that such a cave has been found on the Mesoamerican periphery. This discovery and accompanying radiocarbon dates are thus of considerable importance to Nicaraguan and to regional prehistory and rock art studies.

DATED ROCK PAINTINGS AT RED CLIFFS, ARIZONA

ABSTRACT This article presents radiocarbon dates for painted motifs at Red Cliffs, west of Sedona in the northeastern corner of Yavapai County, Arizona. All rock painting shields at the Red Cliffs sites have usually been attributed to the Sinagua. Black pigment from one shield motif and an overlying white dot on another motif yielded uncalibrated radiocarbon dates of 1080 and 550 years B.P., respectively. The black pigment sample dates to a time when the region was extensively used. Assuming that the two shields were painted contemporaneously, the age of the white dot sample suggests that a later cultural group altered Sinagua paintings at Red Cliffs after the Sinagua abandoned the region.

Identification of anthraquinone dye colourants in red fibres from an Ohio Hopewell mound site by direct analysis in real time mass spectrometry

AbstractAmong prehistoric native groups of North America, the Ohio Hopewell was a particularly notable cultural manifestation that prevailed during the Middle Woodland Period (ca. 2100–1500 BP). The group is defined by the construction of elaborate burial mounds, evidence of ritual burning and cremation ceremonies, and a multitude of intricately decorated objects formed from materials obtained through extensive trade networks. While relatively few textile artefacts survive, those that have been preserved reflect a comprehensive knowledge of plant and animal fibre, dye, and pigment sources, and manipulation of those materials to create complex decorated fabric structures. The research reported herein is part of a programme to understand the materials used and the processes of colouration employed prehistorically. To investigate the sources of dye colourants, we applied direct analysis in real time – time-of-flight mass spectrometry (DART-MS) to both comparative materials and archaeological fibres from thre...

Sequencing Analytical Methods for Small Sample Dating and Dye Identification of Textile Fibers: Application to a Fragment from Seip Mound Group, Ohio

Examination of fibers from a colored fabric fragment from Seip Mound Group, Ohio, demonstrates the utility of sequencing analytical techniques: (1) minimally destructive pretreatment to remove humic acids followed by plasma-chemical oxidation, in preparation for accelerator mass spectrometric determination of radiocarbon age and (2) direct analysis in real time mass spectrometry (DART-MS) of the pretreatment solution, for the determination of red colorants. Pretreatment followed by plasma-chemical oxidation provided the opportunity to date 3 mg of fiber using just 200 mcg of carbon. Examination of the pretreatment solution by DART-MS confirmed the composition of anthraquinones consistent with those from bedstraw root (Galium sp.). The date determined (1,805 ± 35 B.P.) places the textile in the midrange of radiocarbon dates previously obtained for the Seip earthworks; identification of the dye plant shows that the Hopewell possessed a sophisticated knowledge of plants and their uses.

Direct analysis in real time-mass spectroscopy for identification of red dye colourants in Paracas Necropolis Textiles

Abstract The Paracas Necropolis on the south coast of Peru is renowned for the elaborate funerary bundles recovered from that dry sandy region. These bundles contained the remains of male leaders within the Paracas communities surrounded by multiple layers of plain cloth and garments with embroidered designs. The methods and materials used in dyeing the yarns used to embellish these ancient fabrics are still not well understood, and the research presented herein seeks to add to that body of knowledge. To investigate the sources of dye colourants in samples from Paracas Necropolis textiles, we applied direct analysis in real time–time-of-flight mass spectrometry (DART-MS). This new methodology has both advantages (analyses are rapid and require little or no sample preparation) and disadvantages (e.g. inability to identify intact carminic acid) compared to existing ones used in the analysis of dye colourants. Direct analysis in real time mass spectra were collected on chemical standards, botanical materials and comparative reference samples prepared with Relbunium roots and cochineal insects (Dactylopius sp.), and the results are compared to red fibres obtained from several different textiles within two different funerary bundles from the Museo Nacional de Arqueología Antropología e Historia in Lima, Peru. The results from the DART-MS analysis of these red fibres show that the compounds present are consistent with the presence of dye obtained from Relbunium species, and cochineal insects were not used to colour these fibres. Statement of significance DART-MS is an efficient and effective method to identify red colourant composition in small samples of fibres removed from archaeological textiles. Of significant note is the ability to differentiate isomers present in Relbunium and other anthraquinone dyes. Colourants in Relbunium are readily distinguished. Although a component of carminic acid from cochineal is less reliably positively identified by DART-MS, it is possible to use a simple extraction and ionization method to confirm or exclude the presence of carminic acid. Relbunium and cochineal are known to have been used in Paracas textiles. Not only does DART-MS aid in identification of colourants using small amounts of material and without significant sample preparation, the information can be used to distinguish fibres that were prepared differently thus indicating past knowledge of dyeing technology. The information can also aid in separating periods of artefact manufacture, and guide development of a conservation strategy. GRAPHICAL ABSTRACT

Clinical Test Strips for Rapid Identification of Binder Materials in Rock Paintings

Clinical test strips were developed by the Bayer Corporation in the 1960s for rapid and simple analysis of urine samples. The test strips consist of a waterproof plastic strip with reagent-impregnated pads that undergo color changes to indicate pH or the presence of protein, glucose, or blood. The blood diagnostic is based on the fact that the heme iron complex catalyzes the reaction between diisopropylbenzene dihydroperoxide with 3,3′,5,5′-tetramethylbenzidine to give a green or blue color. Bayer (2003) specifies that optimal results require the use of fresh, well-mixed, uncentrifuged urine.