Review of Relevant Work

October 29, 2022

To avoid major interferences such as Argon-40 in measuring carbon in dripwaters and plate calcite, minor isotopes of calcium have been chosen. By measuring Calcium-43, Calcium-44, and Calcium-46, an average concentration of Calcium-40 will be able to be calculated as Argon-40 is a significant interference at mass 40. By utilizing the Agilent 7500ce’s collision/reaction cell in helium mode, interferences at those minor isotopes will be effectively eliminated. Table 1 outlines some potential interferences for the chosen analytes. Ideally, these interferences will be eliminated using helium mode in the ICP-MS.

Table 1: Each analyte and its potential interferences during ICP-MS runs. 

Below 200 ppm, calcium has been demonstrated to have a negligible effect on the TE ratios that we are investigating (Yu et al., 2005). Compared to Yu et al. (2005), decreasing the calcium concentration to 60 ppm has been shown to reduce matrix effects even further (Tremaine and Froelich, 2013). We will be using NIST 1643e as a standard in dripwaters, and in plates using two carbonate standards (USGS MACS-3 and FEBS-1). In order to eliminate cross-calibration efforts between modes, all analytes will be measured in pulse mode, as adapted from Yu et al. (2005). This will enable greater sensitivity and accuracy of the data.