A simple method for the determination of lead isotope ratios in ancient glazed ceramics using inductively coupled plasma - Quadrupole mass spectrometry

摘要

A method for the determination of lead isotope ratios in glazes by inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) has been developed for distinguishing antique lead-glazed ceramics from different ages, workshops and geographical regions. Glazes were leached in 4% (v/v) acetic acid for 24 hours, and the leachates diluted with 2% (v/v) nitric acid to get final lead concentrations around 100 ng mL(-1) Acquisition parameters were optimized to get the highest precision attainable by ICP-QMS. Integration times of 20 seconds per isotope were selected, resulting in an analysis time per sample of less than six minutes. Relative standard deviations of the lead isotope ratios ranged from 0.2% for Pb-206/Pb-204 to 0.05% for Pb-207/Pb-206. For the lead glazes studied, it was found that the attainable precision was not a limitation because the lead-isotope-ratio variations between groups of samples were large enough, allowing classification of ceramics with respect to production workshops or glaze types, and proving that different lead raw materials were used according to the quality of the ceramics. In addition to the performance of the technique, the simplicity of the sample treatment proposed, based on the leaching of a glaze fragment with acetic acid, offers several advantages linked to cultural heritage studies, such as handling very small samples and using short analysis times necessary for dealing with a large number of samples to be analyzed.