Development and validation of an HPLC-UV method for iodixanol quantification in human plasma

Iodixanol is a widely used iso-osmolar contrast medium agent. Similar to iohexol, it can also be a good exogenous marker for the measurement of glomerular filtration rate (GFR). This article describes the development and validation of an HPLC-UV method for quantification of iodixanol in human plasma. Internal standard, iohexol (20 μl, 1 mg/ml), and perchloric acid (30 μl, 20%, v/v) were added to plasma samples (300 μl), followed by neutralization with 10 μl potassium carbonate (5 M). Samples were centrifuged and 10 μl of the supernatant was injected onto a C18 EPS analytical column (3 μm particle size, 150 mm × 4.6 mm). The extraction method yielded >95% recovery for both iodixanol and iohexol. The mobile phase consisted of 0.1% (w/v) sodium formate buffer and acetonitrile. Iohexol and iodixanol peaks were eluted at ∼5 and 9 min, respectively using a fast gradient method. The assay lower limit of detection was 2.0 μg/ml and lower limit of quantification was 10 μg/ml. The calibration curves, assessed in six replicates, were linear over an iodixanol concentration range of 10–750 μg/ml. Intra- and inter-day accuracy was >95% and precision expressed as % coefficient of variation was <10%. This method is simple, accurate, precise and robust and can potentially be used for iodixanol quantification in large-scale clinical studies.