| Abstract: | Concentrations of the vasodilator isosorbide dinitrate (ISDN) in human plasma can be measured with good sensitivity (about 0·2–0·5 ng ml?1) using electron-capture gas chromatography after a one-stage extraction. The mean recovery of ISDN from plasma was 83 per cent ± 9 standard deviation (S.D.). The precision of the method for the measurement of ISDN in plasma ranged from ± 14 per cent at 1 ng ml?1 to ± 7 per cent at 5 ng ml?1 to ± 4 per cent at 50 ng ml?1. The 95 per cent confidence limits of the least-squares regression calibration line forced through the origin were ± 100 per cent at 1 ng ml?1, ± 11 per cent at 10 ng ml?1, and ± 8 per cent at 30 ng ml?1. The method has been used to assay many samples withdrawn after doses of drug at therapeutic levels to normal subjects. |
