Homogeneous chemiluminescent assays for free choline in human plasma and whole blood.

Choline was oxidized in the presence of choline oxidase and the hydrogen peroxide generated was detected using a chemiluminescent acridinium-9-carboxamide. The dose response for choline (0-150 microM) was established in buffer and was validated for the quantification of choline in human plasma and whole blood. This homogeneous assay was performed in a 96-well microplate format and required minimal sample volume (4 microL) and short analysis time (<5s per well). The new assay(s) correlated well (R>0.98, plasma; R>0.97, whole blood) with LC-MS/MS.