TABLE 1.

The tri-mode analytical platform for assay of urea.

System	Methods	LR (nmol/L)	Regression equation	Coefficient	DL (nmol/L)
CDFe-Urea	FL	3.33–20	ΔF405 nm = 27.5C + 28.5	0.9856	1.4
	SERS	3.33–16.65	$\Delta I_{1598{\text{cm}}^{-1}}=166.3\text{C}+221.1$	0.9946	1.3
	RRS	2.5–12.5	ΔI370 nm = 17.6C−2.9	0.9939	1.6
CDFeN-Urea	FL	3.33–20	ΔF405 nm = 22.3C + 15.7	0.9880	1.0
	SERS	1.1–16.65	$\Delta I_{1598{\text{cm}}^{-1}}=90.8\text{C}+29.1$	0.9895	0.06
	RRS	2.5–12.5	ΔI370 nm = 21.0C−6.5	0.9909	1.71