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

Table 5 Descriptive statistics of elements contents (weight%) in KACST403 CRM

Element	Average	SD	RSD%	RAD%	Skewness	Kurtosis
Al	1.756	0.0098	0.56	0.44	− 0.28	0.04
Br	0.004	0.0004	9.90	6.71	− 1.68	3.37
Ca	22.57	0.0488	0.22	0.18	− 1.23	− 0.84
Cl	1.042	0.0185	1.77	1.26	0.15	0.03
Cr	0.048	0.0039	8.19	6.38	− 0.68	− 0.07
Fe	1.026	0.0335	3.26	2.09	2.54	6.55
K	0.818	0.0021	0.25	0.22	− 0.17	− 2.10
Mg	1.199	0.0069	0.58	0.41	0.17	0.34
Mn	0.030	0.0010	3.24	2.85	− 0.37	− 2.13
Na	1.121	0.0121	1.08	0.91	0.41	− 1.53
Ni	0.014	0.0012	8.56	6.77	0.42	− 1.36
P	0.026	0.0012	4.79	3.62	− 0.45	− 1.22
Rb	0.004	0.0002	6.12	4.93	− 0.12	− 0.77
S	0.198	0.0034	1.72	1.48	− 0.20	− 2.20
Si	11.57	0.0488	0.42	0.35	− 1.23	− 0.84
Sr	0.308	0.0011	0.36	0.29	− 0.25	− 0.94
Ti	0.190	0.0008	0.43	0.30	0.00	− 1.20
Zn	0.003	0.0007	20.7	16.9	0.16	− 1.76

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