. 2014 May 13;53(16):8311–8321. doi: 10.1021/ic5006083

Table 4. Proton Exchange Rate Constants of ParaCEST Agents in Different Media.

complex	buffer^a (s^–1)	rabbit serum^a (s^–1)	egg white^a (s^–1)	agarose^a (s^–1)
[Co(L)]²⁺	240 ± 70	1600 ± 650	860 ± 160	850 ± 70
[Ni(L)]²⁺	240 ± 20	3200 ± 300	1700 ± 400	890 ± 190
[Fe(L)]²⁺	500 ± 50	630 ± 200	760 ± 180	520 ± 30

Exchange rate constants obtained for solutions containing 10 mM complex in 20 mM HEPES pH 7.3–7.4 and 100 mM NaCl, rabbit serum, egg white or 4% agarose gel (w/w) at 11.7 T. B₁ varied between 8 and 24 μT, with an radio frequency presaturation pulse applied for 4 s at 37 °C.