Study of New CGSP-P Series Phosphate Matrix Reference Materials for LA-ICP-MS

A series of three CGSP-P phosphate matrix reference materials, with variable element mass fractions, were synthesised by co-precipitation with CaCl₂ and (NH₄)₃PO₄ to form a hydroxylapatite matrix. Each powder sample was packaged into multiple bottles and pressed into tablets as replicates. The within-bottle homogeneity was evaluated by the repeatability of element mass fractions of six spots in per tablet of CGSP-Ps by LA-ICP-MS. For the between-bottle homogeneity evaluation, one approach adopted the % RSD of element mass fractions in twelve different tablets from twelve bottles in the same reference material in comparison with the repeatability field of LA-ICP-MS analyses obtained from homogeneous glasses, and the other used a one-way analysis of variance (ANOVA) approach. Most of the elements (e.g., Mg, Ca, P, Mn and REE) were homogenous within 10% RSD, and other elements (e.g., Si, Al, K, Rb, Cs and Ni) were considered heterogeneous (with > 20% RSD). All of the elements passed the t-test except Ni in CGSP-P3, and V, Cr, Ni, Zr, Gd, Dy and Th in CGSP-P4 after a 29-month period stability examination by LA-ICP-MS. The preliminary reference values and standard uncertainties for CGSP-Ps are given with a network of methods and eight laboratories by bulk analysis according to ISO Guide 35:2006 and JJF 1343-2012.