Identification of Ritual Blood in African Artifacts Using TOF-SIMS and Synchrotron Radiation Microspectroscopies

Abstract

A new protocol is implemented to demonstrate the presence of blood in the patina of African art objects from Mali. Divided into three steps, the protocol first consists in demonstrating the presence of proteins and localizing them in the sample's cross sections using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and synchrotron-based infrared microspectrometry (µFT-IR). In a second time, TOF-SIMS is used to investigate heme, which is a blood marker. If heme is missing, which could mean that it is too degraded to be detected, X-ray microfluorescence (µXRF) and X-ray absorption near-edge microspectroscopy (µXANES) are used to prove the presence of iron in the protein area and to get a fingerprint of its chemical environment. This permits us thus to demonstrate that iron is indeed linked with proteins and not with mineral phases of the sample. Coupled with the ritual context of the objects, this constitutes a proof of the use of blood. Thanks to this protocol, which has the major advantage of avoiding false positive results, the presence of blood has been demonstrated in seven out of the eight studied samples.African art objects collected in the course of colonial or ethnological expeditions during the 20th century represent unique and very precious material testimony of values and practices, which have in some cases totally disappeared today. Numbers of these objects, which are now parts of the collections of art or ethnologic museums, are partially or completely covered with a so-called "patina". Indeed, different substances were spread out on the objects during religious and ritual ceremonies. 1 Various examples of such patinas in African statuary come from different ethnic groups like the Baoule in Ivory Coast, 1 Lobi in BurkinaFaso, 2 Fang in Gabon, but also Bambara and Dogon in Mali. 3,4 Some of these patinas are constituted by materials which have become solid on the object's surface, like a more or less thick crust.The bibliographic references come from ethnologic studies, such as the very important work of Marcel Griaule 5,6 who has collected a large number of ritual objects associated with very precious accounts about traditional beliefs of the Dogon. A better understanding of these patinas could explain details of the practices used during centuries throughout ceremonies. An important challenge is to extract unequivocal information about the original constituents of these patinas and the techniques used for their applications on ritual objects. Many substances are used, each product having its religious meaning and importance. Among these, blood is often reported in different religious contexts, 7,8 linked to animal sacrifices. Confirmation of the presence of blood would be very meaningful.In a previous paper, we described an original analytical protocol based on chemical imaging techniques to study patinas from African statues. 9 The protocol permitted us to study both the mineral and the organic parts of a sample without extraction of

Hemoglobin-derived porphyrins preserved in a Middle Eocene blood-engorged mosquito

“…2 D and E). Comparison of the exact masses of analyzed peaks with the hemoglobin control and calculated masses of porphyrin derivatives (Table S1), as well as previous ToF-SIMS studies on heme, strongly indicate that the iron is still part of the porphyrin structure (25,(28)(29)(30). The most significant difference between the spectra of the female mosquito abdomen and the spectra of the purified pig hemoglobin is the absence of the peak for the intact heme ion [M] + at m/z 616.18 and the fragment ions centering at m/z 557.14, [M-CH 2 COOH] + .…”

Imaging Mass Spectrometry for Visualization of Drug and Endogenous Metabolite Distribution: Toward In Situ Pharmacometabolomes

“…Studies describing detection and imaging of complex lipids (e.g., glycerophospholipids and glycosphingolipids) and simple lipids (e.g., cholesterol, acylglycerides, and fatty acids) have been reported. In addition, other metabolites with superior ionization efficiency such as heme, which is a prosthetic group consisting of an iron atom contained in the center of a porphyrin ring, have also been investigated, even in an African ritual art object (Mazel et al 2007; summarized in Table 2). …”

ToF‐SIMS Study of Organic Materials in Cultural Heritage: Identification and Chemical Imaging

“…However, ToF-SIMS can also be used, with a different approach [Mazel et al 2007]. Different objects, Dogon and Bamana, presenting thick patina were studied to prove whether or not blood was employed for making the patina.…”