Author(s)

Germán Velásquez^1,2*, Anastassia Y. Borisova^3,4, Sandrine Baron⁵, Luc Robbiola⁵

¹Advanced Mining Technology Center (AMTC), FCFM, Universidad de Chile, Santiago, Chile.
²Universidad Central de Venezuela, Instituto de Ciencias de la Tierra, Caracas, Venezuela.
³Géosciences Environnement Toulouse, Université de Toulouse, UPS OMP-CNRS, Toulouse, France.
⁴Geological Department, Lomonosov Moscow State University, Moscow, Russia.
⁵Université de Toulouse, CNRS, Laboratoire TRACES (UMR 5608), Toulouse, France.

Direct analysis of copper-base alloys using laser ablation techniques is an increasingly common procedure in cultural heritage studies. However, main discussions remain focused on the possibility of using non-matrix matched external reference materials. To evaluate the occurrence of matrix effects during in situ microanalysis of copper-base materials, using near infrared femtosecond laser ablation techniques (NIR fs-LA-ICP-MS), two bronzes, i.e., (Sn-Zn)-ternary and (Sn)-binary copper-matrix reference materials, as well as a reference synthetic glass (NIST-SRM-610) have been analyzed. The results have been compared to data obtained on a sulfide-matrix reference material. Similar values in relative sensitivity averages of ⁶³Cu, ¹¹⁸Sn and ⁶⁶Zn, as well as in ¹¹⁸Sn/⁶³Cu and ⁶⁶Zn/⁶³Cu ratios were obtained, for all analyzed matrix types, i.e., copper-base-, silicate-, and sulfide-reference materials. Consequently, it is possible to determinate major and minor element concentrations in copper alloys, i.e., Cu, Sn and Zn, using silicate and sulfide reference materials as external calibrators, without any matrix effect and over a wide range of concentrations (from wt.% to ppm). Equally, Cu, Sn and Zn concentrations can be precisely determined in sulfides using homogeneous alloys (reference) materials as an external calibrator. Thus, it is possible to determine Cu, Sn and Zn in copper-base materials and their ore minerals, mostly sulfides, in a single analytical session, without requiring specific external calibrators for each matrix type. In contrast, immiscible elements in copper matrix, such as Pb and Fe show notable differences in their relative sensitivity values and ratios for different matrix-materials analyzed, implying that matrix-matched external calibrations remain to be applied for their trace quantification.

Copper Alloys, Reference Material, Matrix Effect, In-Situ Metal Determinations, Near-Infrared Femtosecond Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (NIR fs-LA-ICP-MS)

Velásquez, G. , Borisova, A. , Baron, S. and Robbiola, L. (2018) In Situ Analysis of Copper Alloys by Femtosecond Laser Ablation Inductively Coupled Plasma Mass Spectrometry: Constrains on Matrix Effects. American Journal of Analytical Chemistry, 9, 150-161. doi: 10.4236/ajac.2018.93013.