Sensitive determination of four general anaesthetics in human whole blood by capillary gas chromatography with cryogenic oven trapping

Four general anaesthetics, sevoflurane, isoflurane, enflurane and halothane, in human whole blood, have been found measurable with very high sensitivity by capillary gas chromatography–flame ionization detection (GC–FID) with cryogenic oven trapping upon injection of headspace (HS) vapor sample. To a 7-ml vial, containing 0.48 ml of distilled water and 20 μl of internal standard solution (5 μg), a 0.5-ml of whole blood sample spiked with or without anaesthetics, was added, and the mixture was heated at 55°C for 15 min. A measure of 10 ml HS vapor was injected into the GC in the splitless mode at −40°C oven temperature, which was programmed up to 250°C. All four peaks were clearly separated; no impurity peaks were found among their peaks. Their extraction efficiencies were about 10%. The calibration curves showed good linearity in the range of 0.5–20 μg/ml; their detection limits were 10–100 ng/ml, which are almost comparable to those by previous reports. The coefficients of intra-day and day-to-day variations were 6.5–9.8 and 7.3–17.2%, respectively. Isoflurane or enflurane was also measured from whole blood samples in which three volunteers inhaled each compound.