Accurate Reporting of Key Trace Elements in Ruby and Sapphire Using Matrix-Matched Standards

Abstract

To improve the accuracy and efficiency of trace element analysis in ruby and sapphire, standards sets containing matrix-matched corundum with targeted levels of beryllium, magnesium, silicon, titanium, vanadium, chromium, iron, and gallium were created. Ultra-high-purity corundum was also incorporated as a “true matrix zero.” To our knowledge, these sets contain the most accurate standards for the key trace elements in corundum today. The standards were designed to cover the optimal range of the main trace elements typically characterized in natural ruby and sapphire. Additionally, we were able to accurately quantify silicon in corundum by successfully resolving the ^(28)Si^+ peak from the ^(27)Al^1H^+ peak using the superior mass resolving power of secondary ion mass spectrometry (SIMS) as compared to laser ablation–inductively coupled plasma–quadrupole mass spectrometry (LA-ICP-QMS).