α-Lipoic acid is a natural environmentally benign chemical that is integral to all plants and mammals and is patented as an agent for the cure of many diseases. It has also been demonstrated that α-lipoic acid acts in-vivo for the detoxification of both arsenic and mercury in biochemical studies dating back to the late 1950’s (Reiss et al (1958); Reiss et al (1958); Grunert (1960); and Wagner (1956)). It is known that α-lipoic acid does not require reduction to bind to mercury (Brown, 1968), however, the literature does not indicate whether reduction is required for binding to arsenic. It has been demonstrated that reduced α-lipoic acid binds strongly to arsenic in water (Spuches et al, 2005). Thus, due to the attributes of α-lipoic acid as a natural healing and detoxification agent and its known ability to react with arsenic and mercury, it is deemed to be the most appropriate cleaning agent for artifacts.
In this study, aqueous α-lipoic acid solutions were developed and reduced using natural sunlight and laboratory ultra violet lamps. The solubility in various organic and inorganic solutions were examined, and variables that may impact the reduction and solubility, such as pH and temperature, were examined. Arsenic and mercury on natural materials such as cotton, wool, paper and feathers were studied using a Niton handheld X-ray Fluorescence Spectrometer (XRF) to monitor contamination levels. A processing sequence that optimized decontamination was developed by running a series of full factorial experiments, which were analyzed using analysis of variance (ANOVA) techniques.
This research was made possible through Grant MT-2210-05-NC-06 from the National Center for Preservation Technology and Training (NCPTT).