Table 6.

Comparison of chromium (Cr) concentrations of spiked rumen fluid samples containing high (0.50 g/L), medium-high (0.25 g/L), medium-low (0.10 g/L), or low (0.005 g/L) concentrations of Cr as measured using an external calibration curve or the internal calibration of an energy dispersive X-ray fluorescence analyzer. The percent difference of the resulting concentration as extrapolated from an external calibration curve or internal calibration to determine which calibration method was more accurate

	Cr concentration, g/L				Percent difference		Recovery, %	Intra-assay CV	Inter-assay CV
	External calibration curve	Internal calibration	SEM1	P-value	External calibration curve	Internal calibration
High, 0.50 g/L	0.474	0.492	0.0001	<0.001	3.59	1.08	94.8 ± 5.64	3.32	5.83
Medium-High, 0.25 g/L	0.233	0.246	0.0003	<0.001	4.75	1.08	114.9 ± 22.80	2.63	2.45
Medium-Low, 0.10 g/L	0.109	0.120	0.0001	<0.001	5.66	11.76	108.6 ± 18.08	4.69	15.30
Low, 0.005 g/L	0.003	0.013	0.0006	<0.001	36.36	51.61	64.6 ± 11.23	11.02	10.21

¹Standard error of the mean (n = 60).