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.