Fundamental studies on the ablation behaviour of carbon in LA-ICP-MS with respect to the suitability as internal standard

Abstract

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is considered a mature technique for the quantitative analysis of various soft and solid materials but is still lacking suitable calibration standards, in particular, for biological and medical applications. Therefore, most quantification strategies rely on in-house prepared standards. Due to its availability and apparent homogeneity in biological and medical matrices carbon is frequently used as an internal standard. Although the applicability of carbon as internal standard has already been in dispute over years its behaviour during LA is not well-understood. This work deals with the analysis of twelve common carbon matrices using a gas exchange device (GED) to investigate the formation of carbon-containing gaseous species (CCGS) during LA. A matrix-dependent partitioning of carbon into CCGS and carbon containing particles (CCP) was observed while trace element analytes are exclusively transported as the particulate phase. The production of CCGS was also found to critically depend on the presence or absence of oxygen (matrix or gas impurities) and the affinity of matrix constituents towards oxygen.