Use of the Relaxometry Technique for Quantification of Paramagnetic Ions in Aqueous Solutions and a Comparison with Other Analytical Methods

Table 2

Linear regression parameters for relaxometry and spectrophotometry calibration curves.

	Ion	Slope	Intercept
Spinlock	Ni^2+	572 ± 3	0.404 ± 0.001	0.9998
	Cu^2+	1491 ± 8	0.402 ± 0.002	0.9998
	Cr^3+	7370 ± 158	0.420 ± 0.010	0.9978
	Mn^2+	31487 ± 282	0.405 ± 0.003	0.9993
UNMR	Ni^2+	632 ± 4	10.4 ± 0.1	0.9998
	Cu^2+	1141 ± 8	10.0 ± 0.3	0.9996
	Cr^3+	9570 ± 130	13.4 ± 0.2	0.9993
	Mn^2+	28517 ± 294	10.3 ± 0.3	0.9992
SP	Ni^2+	5.01 ± 0.01	0.0004 ± 0.0003	0.9999
	Cu^2+	12.45 ± 0.04	0.005 ± 0.002	0.9999
	Cr^3+	16.28 ± 0.29	0.0365 ± 0.0513	0.9991

Mean ± SD (); = intercept + slope[ion], where (s⁻¹) is the inverse of and the ion concentration is given in mol L⁻¹; = intercept + slope[ion], where is the absorbance in 810, 422, and 394 nm for Cu²⁺, Cr³⁺, and Ni²⁺, respectively, and the ion concentration is given in mol L⁻¹.