Between-bottle homogeneity test of new certified reference materials employing wavelength dispersive X-ray fluorescence spectrometry

Table 6 Descriptive statistics of elements contents (weight%) in KACST301 CRM

Element	Average	SD	RSD%	RAD%	Skewness	Kurtosis
Al	0.0048	0.0009	19.1	16.0	− 1.23	− 0.82
Ca	0.5953	0.0005	0.08	0.07	1.23	− 0.84
Cl	0.4019	0.0097	2.42	2.03	− 0.46	− 1.68
Cu	0.0141	0.0004	2.59	2.06	0.12	− 1.16
Fe	0.0489	0.0112	23.0	18.2	− 0.96	− 0.57
K	2.5771	0.0550	2.13	1.76	0.66	− 1.30
Mg	0.0567	0.0008	1.36	1.12	− 0.25	− 1.28
P	0.0815	0.0017	2.09	1.76	0.07	− 1.91
Rb	0.0080	0.0003	3.76	3.13	− 0.83	− 1.28
S	0.0809	0.0002	0.21	0.17	− 0.62	− 1.40
Si	0.0454	0.0145	31.9	20.6	2.58	6.75
Sr	0.0091	0.0011	11.6	9.27	0.21	− 1.03
Zn	0.0068	0.0013	18.7	14.7	0.33	− 0.74

SD standard deviation, RSD relative standard deviation, RAD relative average deviation