Anaesthetic concentrations of enflurane and methoxyflurane in rat brain in-vivo and in-vitro

Determination of volatile anesthetics isoflurane and enflurane in mouse brain tissues using gas chromatography-mass spectrometry

INTRODUCTION

A method for determination of the volatile anesthetics, isoflurane, and enflurane in mouse brain tissues using headspace gas chromatography-mass spectrometry (GC-MS) is described.

METHODS

Halothane was used as internal standard (I.S.). Brain samples were completely homogenized in ice-cold water and isoflurane, enflurane, and I.S. were extracted with headspace. One milliliter of headspace gas was injected onto the GC-MS and separation was achieved by using porous layer open tubular (PLOT) capillary column with a solid stationary phase (GSC). As a result, isoflurane, enflurane, and halothane were cleanly separated.

RESULTS

The method demonstrated satisfactory recovery (72% and 76% for isoflurane and enflurane, respectively) and linear calibration ranges of 0.015-2.20 and 0.0152-3.94 microg/sample for isoflurane and enflurane, respectively. Reproducibility calculated as CV% was 3.3-3.9% for all intraday and interday determinations. The procedure was applied for quantitation of isoflurane and enflurane in about 300 mouse brain samples for genetic behavioral study.

DISCUSSION

The method was achieved and shown to be effective.

Simple and rapid determination of enflurane in human tissues using gas chromatography and gas chromatography-mass spectrometry

A simple, rapid and reliable method was devised to determine the levels of enflurane in human tissues, using gas chromatography and gas chromatography-mass spectrometry. 1,4-Dioxane was used as an internal standard (I.S.). Enflurane and the I.S. were extracted from 0.25 g of body tissues using an automatic headspace sampler and 1 ml of headspace gas was injected into the gas chromatograph. Enflurane was analyzed qualitatively by gas chromatography-mass spectrometry and quantitatively by gas chromatography with a flame-ionization detector. The calibration curves in all tissues examined were linear in the concentration range 1-100 microg/0.25 g. The lower limit of detection was 200-300 ng/0.25 g. The accuracy and precision of this method were evaluated at two different concentrations, 1 and 20 microg/0.25 g. The coefficient of variation ranged from 3.4-13.4%. We used this method to determine the presence of enflurane in tissues from an autopsied individual who died suddenly during extirpation of a malignant tumor.