Determination of Arsenic, Mercury and Barium in Herbarium Mount Paper using 5 Dynamic Ultrasound-Assisted Extraction prior to Atomic Fluorescence and Absorption 6 Spectrometries 7 8
Abstract 25 A dynamic ultrasound-assisted extraction method using Atomic Absorption and Atomic 26 Flourescence spectrometers as detectors was developed to analyse mercury, arsenic and 27 barium from herbarium mount paper originating from the herbarium collection of the 28 National Museum of Wales. The variables influencing extraction were optimised by a 29 multivariate approach. The optimal conditions were found to be 1% HNO 3 extractant solution 30 used at a flow rate of 1 mL min -1 . The duty cycle and amplitude of the ultrasonic probe was 31 found to be 50% in both cases with an ultrasound power of 400 W. The optimal distance 32 between the probe and the top face of the extraction chamber was found to be 0 cm. Under 33 these conditions the time required for complete extraction of the three analytes was 25 min. 34 2 Cold vapour and hydride generation coupled to atomic fluorescence spectrometry was 1 utilized to determine mercury and arsenic, respectively. The chemical and instrumental 2 conditions were optimized to provide detection limits of 0.01ng g -1 and 1.25 ng g -1 for 3 mercury and arsenic, respectively. Barium was determined by graphite-furnace atomic 4 absorption spectrometry, with a detection limit of 25 ng g -1 . By using 0.5 g of sample, the 5 concentrations of the target analytes varied for the different types of paper and ranged 6 between 0.4-2.55 µg g -1 for Ba, 0.035-10.47 µg g -1 for As and 0.0046-2.37 µg g -1 for Hg. 7 8
