Sensitive and simple determination of mannitol in human brain tissues by gas chromatography-mass spectrometry

A simple, reliable and sensitive gas chromatographic-mass spectrometric met hod was devised to determine the level of mannitol in various human brain t issues obtained at autopsy. Mannitol was extracted with 10% trichloroacetic acid solution which effectively precipitated brain tissues. The supernatan t was washed with tert.-butyl methyl ether to remove other organic compound s acid to neutralize the aqueous solution. Mannitol was then derivatized wi th 1-butaneboronic acid and subjected to GC-MS. Erythritol was used as an i nternal standard. For quantitation, selected ion monitoring with m/z 127 an d 253 for mannitol and m/z 127 for internal standard were: used. Calibratio n curves were linear in concentration range from 0.2 to 20 mug/0.1 g and co rrelation coefficients exceeded 0.99. The lower detection limit of mannitol in distilled water was 1 ng/0.1 g. Mannitol was detected in control brain tissues, as a biological compound, at a level of 50 ng/0.1 g. The precision of this method was examined with use of two different concentrations, 2 an d 20 mug/0.1 g, and the relative standard deviation ranged from 0.8 to 8.3% . We used this method to determine mannitol in brain tissues from an autops ied individual who had been clinically diagnosed as being brain dead. Cardi ac arrest occurred 4 days later. (C) 2001 Elsevier Science B.V. All rights reserved.