HPLC‐UV+AMS analysis for bile samples
two‐step
The pooled bile string extract solution was spiked with nonradiolabeled standards, mixed and injected (100 μL), then chromatographed by HPLC. The HPLC column eluate was fractionated (12‐s intervals between 15 and 55 min) and collected into prebaked small quartz tubes containing copper oxide wire.Additionally, replicate aliquots of the injection solution of the spiked pool (4 × 10 μL) were separately pipetted into the same type of quartz tubes as stated above for the determination of HPLC column recovery of injected radioactivity.Analysis by AMS requires conversion of samples via a two‐step process of oxidation to carbon dioxide (CO