Determination of Guan-Fu Base A, a new anti-arrhythmic, in human plasma by gas chromatography and electron–capture detection

A gas chromatographic–electron capture detection (GC–ECD) method has been developed for determining Guan-Fu Base A (GFA), an experimental anti-arrhythmic, in human plasma. The method was based on one-step liquid–liquid extraction with toluene and chemical derivatization with pentafluoropropionic anhydride followed by GC–ECD. The derivatives of GFA and metoprolol (Met, internal standard) were confirmed by gas chromatography–mass spectrometry (GC–MS) to be dipentafluoropropionyl-GFA and dipentafluoropropionyl-Met. The method was linear over the concentration ranges of 0.1–20.0 and 1.0–30.0 μg/ml with the detection limit of 0.05 μg/ml at S/N=5. The intra- and inter-assay precisions were less than 6 and 10%, and accuracy 99.70±3.30 and 97.60±5.99%, respectively. The absolute recoveries were 81.88, 77.35, 80.79 and 83.85% for GFA at concentrations of 0.5, 1.0, 5.0 and 14.0 μg/ml and 88.24% for Met at 3.0 μg/ml, respectively.