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

Table 7 Descriptive statistics of elements contents (weight%) in KACST302 CRM

Element	Average	SD	RSD%	RAD%	Skewness	Kurtosis
Al	0.146	0.0020	1.34	1.09	− 0.29	− 1.45
Br	0.021	0.0001	0.25	0.23	− 0.37	− 2.80
Ca	3.350	0.0082	0.24	0.17	0.00	− 1.20
Cl	1.147	0.0049	0.43	0.36	− 1.23	− 0.84
Cu	0.018	0.0008	4.67	3.94	− 0.14	− 1.78
Fe	0.291	0.0025	0.86	0.67	0.90	− 0.17
K	0.976	0.0042	0.43	0.38	− 0.40	− 2.31
Mg	0.240	0.0012	0.49	0.37	0.67	− 0.45
Mn	0.033	0.0048	14.6	13.3	− 0.36	− 2.77
Na	0.102	0.0005	0.48	0.40	− 1.23	− 0.84
Ni	0.017	0.0028	16.76	13.6	− 1.11	− 0.59
P	0.095	0.0014	1.51	1.28	− 0.13	− 1.97
S	0.542	0.0033	0.61	0.51	− 0.14	− 1.91
Si	6.404	0.0079	0.12	0.10	− 1.11	0.27
Sr	0.016	0.0006	4.04	3.51	− 0.55	− 1.85
Ti	0.027	0.0008	2.98	2.24	0.17	− 0.99
Zn	0.014	0.0012	8.28	7.05	− 0.30	− 1.64

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