Pigment analysis authentication

Microscopists in every technical field use the microscope to characterize, compare, and identify a wide variety of substances, eg, protozoa, bacteria, vimses, and plant and animal tissue, as well as minerals, building materials, ceramics, metals, abrasives, pigments, foods, dmgs, explosives, fibers, hairs, and even single atoms. In addition, microscopists help to solve production and process problems, control quaUty, and handle trouble-shooting problems and customer complaints. Microscopists also do basic research in instmmentation, new techniques, specimen preparation, and appHcations of microscopy. The areas of appHcation include forensic trace evidence, contamination analysis, art conservation and authentication, and asbestos control, among others. 

Anthocyanins are water-soluble pigments which impart the red, purple, and blue coloration of many fruits, vegetables, and cereal grains. Their analysis is useful for commodity identification since the anthocyanin fingerprint pattern is distinctive for different commodities. The authors laboratory has demonstrated how HPLC anthocyanin analyses can be effectively applied to determine the authenticity of various anthocyanin containing fruit juices (Wrolstad et al., 1994). 

X-ray fluorescence analysis had been used for composition studies of various materials. Probably among the most important applications are research on metals and on inorganic pigments. Analyses similar to the ones I quoted are very helpful in authenticity studies and can aid the cosmetic industry, metallurgy, and so on. The demands archaeological chemistry made (nondestructiveness, small sample size, quick analysis, sensitivity) has helped significantly to develop x-ray fluorescence instrumentation. 

Washall [566] has reviewed analytical pyrolysis of cationic alkylammonium halide surfactants and has shown that analytical pyrolysis is a technique that works well even with trace quantities (low ppm level). For applications which require protection of sample integrity, as in forensic science and in art conservation, analytical pyrolysis is an obvious analytical tool. Bart [563] has reviewed polymer/additive analysis by flash pyrolysis techniques and Challinor [567] the applications of analytical pyrolysis in forensic science. Paints, varnishes, glues, pigments, waxes, organic binder formulations have been studied from the aspects of both conservancy and authentication. 

Analysis has also uncovered at least one forgery. The date of fabrication of Ms 972 from the University of Chicago Special Collections, familiarly known as the Archaic Mark, had been tentatively attributed to the twelfth century. Analysis showed that an iron blue [42] was ubiquitous in this manuscript, raising doubts about its authenticity. The iron blues are the first of the artificial pigments with a known history and an estabhshed date of first preparation. The color was made by the Berlin color makers Johann Jacob Diesbach and Johann Konrad Dippel (1673-1734) in or around 1706 [44,45]. Moreover, according to Gettens and Stout [31, 32], the material is so complex in composition and mediod of manufacture that there is practically no possibility that it was invented in other times and places. This fact, in addition to other evidence [46]—radiocarbon dating of the parchment... 

Another major application of the technique is in the analysis of ancient paints used in a particular period of history or a particular place. This is essential not only for the study of the pigments and materials used by different civilisations, but also for authenticating works of art, restoration work and in lawsuits involving damaged works of art. 

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