New CGSP Carbonate Matrix Reference Materials for LA‐ICP‐MS Analysis

Four CGSP (Chinese Geological Standard Powders) carbonate matrix element reference materials were prepared by a coprecipitation method. The major and trace elements were dissolved from natural rare earth carbonate raw materials in strong acid and precipitated with ammonium bicarbonate or ammonia to form carbonate matrix phases. The carbonate reference materials were ground and pressed into tablets for microanalysis. The element homogeneity and stability in CGSP reference materials were tested by LA‐ICP‐MS using a calibration strategy without an internal standard element and evaluated mainly following ISO Guide 35: 2017 and JJF 1343‐2012. Although the homogeneity of most of elements in the CGSP series were comparable to the repeatability obtained from homogeneous glasses, some elements (e.g., Mo, Se, Ga, Ge, Cd, Ni, Co, U) were found to have some degree of heterogeneity. All of elements passed the t ‐test evaluation in a 32‐month stability examination except for Mo in CGSP‐A, Na, Ge, Mo in CGSP‐B, Ni, Cd, Sn in CGSP‐C, and Al, P, Tb, Ho in CGSP‐D. The certified element mass fraction values and uncertainties were determined with the characterisation of a non‐operationally defined measurand using various bulk analysis methods in eight laboratories. GGSPs will provide a new carbonate calibration reference option for microanalysis.