Automated determination of mercury and arsenic in extracts from ancient papers by integration of solid-phase extraction and energy dispersive X-ray fluorescence detection using a lab-on-valve system

A method to detect the presence and determine the concentration of mercury and arsenic in extracts of ancient papers, based on an approach which allows integration of solid-phase concentration of the target analytes and their detection, is proposed. Automation of the overall process (viz. swelling and conditioning of the sorbent, sample introduction for analytes retention, drying of the sorbent by air for proper measurement, elution and conditioning of the sorbent prior to introduction of the next sample) is achieved by on-line connection of a lab-on-valve system to a laboratory-made methacrylate cell for concentration-measurement. After optimization of the variables influencing the method, characterization of the method provided LODs and LOQs of 0.006 and 0.02 μg g−1 of paper, respectively, for Hg; and 0.007 and 0.027 μg g−1, respectively, for As, with repeatability of 6.37% for Hg and 5.62% for As, and reproducibility of 8.13% and 7.46% for Hg and As, respectively.