A Simple and Sensitive LC-MS/MS for Quantitation of ICG in Rat Plasma: Application to a Pre-Clinical Pharmacokinetic Study

A selective, sensitive, and rapid liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitation of ICG in rat plasma. The chromatographic separation was achieved using an ACE excel C18 (3 mu m, 50 x 3.0 mm) column, with a mobile phase composition of 0.1% formic acid and 0.1% formic acid in acetonitrile, using a gradient flow at a rate of 0.3 mL/min. The MS was operated at a unit resolution in the multiple reaction monitoring mode, using the precursor ion -> product ion combinations of 753.3 -> 330.2 m/z (ICG) and 747.45 -> 717.50 (Cy7.5 amine) with a run time of 5 min. The assay was linear over a concentration range of 1-1000 ng/mL with a regression coefficient (r(2)) of 0.998 or better. The inter and intra-batch precision (% relative standard deviation, %RSD) was lower than 13.5%, with accuracy (%Bias) between -10.03% and 11.56%. The ICG was stable under laboratory storage and handling conditions. The validated method was successfully applied to preclinical pharmacokinetic (PK) studies of ICG at a dose of 0.39 mg/kg in rats. PK parameters suggested the highest plasma concentration within 2 min of intravenous dosing with restricted systemic distribution and rapid clearance.