Laser ablation-inductively coupled plasma-dynamic reaction cell-mass spectrometry for the determination of lead isotope ratios in ancient glazed ceramics for discriminating purposes

Abstract

The potential of laser ablation-single collector-inductively coupled plasma-mass spectrometry for discrimination among Spanish antique lead-glazed ceramics according to age and workshop has been investigated. In order to obtain the required precision, pressurizing the dynamic reaction cell (DRC) with Ne proved to be a significant help. In this way, it was feasible to obtain RSD values in the range 0.15–0.25% (internal precision) for the ratios calculated using the most abundant Pb isotopes (²⁰⁶Pb, ²⁰⁷Pb and ²⁰⁸Pb), under optimized conditions. These values are 2–3 times lower than those that could be achieved in standard (vented) mode and proved to be sufficient for distinguishing between the different groups of samples under study.

The method finally proposed was demonstrated to show interesting features, such as the potential to obtain spatially resolved isotopic information in approximately 30 min measurement time per sample, with negligible (ng level) sample damage. On the other hand, it has to be mentioned that the use of the DRC results in an undesired enhancement in the mass discrimination that has to be corrected for. Only by using a perfectly matrix-matched standard (in the current work, one sample of each group that was analyzed by an alternative procedure in order to obtain a suitable reference value), accurate correction for this effect became possible. Obviously, this is somewhat inconvenient, but the possibility of analyzing the vast majority of the samples in a fast, quasi non-destructive, spatially resolved and cost-effective way (particularly when comparing with the use of dedicated techniques for isotopic analysis) may be appealing for archaeological laboratories.