Table 4.
Phosphorus determination in certified materials compared with ICP-OES and Molybdenum blue colorimetric method using dry digestion procedure

Temperature (°C)	CRMs	Molybdenum blue colorimetric method		Dry ashing method (ICP-OES)
		Measured (mg/kg, mean±SD)	Recovery (%)	Measured (mg/kg, mean±SD)	Recovery (%)
		350°C	SRM 1849a	3,517.43±98.78	88.16	4,295.83±22.26	107.66
SRM 1546	1,246.81±34.68		81.49	1,325.48±60.53	86.63
LGC 7105	408.51±145.50		118.07	369.08±8.44	106.67
LGC 7104	825.62±36.68		100.32	942.23±22.41	114.49
450°C	SRM 1849a	3,794.25±113.68	95.09	4,555.51±64.11	114.17
	SRM 1546	1,465.49±68.67	95.78	1,761.79±41.80	115.15
	LGC 7105	347.30±66.26	100.38	362.14±6.76	104.66
	LGC 7104	863.78±35.57	104.96	992.03±41.91	120.54
550°C	SRM 1849a	3,936.61±9.88	98.66	4,096.96±36.30	102.68
	SRM 1546	1,527.54±29.17	99.84	1,613.39±15.22	105.45
	LGC 7105	393.16±10.16	113.63	348.19±1.18	100.63
	LGC 7104	885.97±13.48	107.65	848.93±13.91	103.15
650°C	SRM 1849a	3,456.76±36.18	86.64	4,479.12±21.10	112.26
	SRM 1546	1,498.93±57.95	97.97	1,718.19±47.56	112.30
	LGC 7105	317.64±13.07	91.80	359.67±7.61	103.95
	LGC 7104	757.86±12.02	92.09	897.30±10.26	109.03
t-test				-0.45 (2.05)