Rapid and Sensitive Gas Chromatography–Mass Spectroscopy Method for the Detection of Mannitol and Sorbitol in Serum Samples

During endoscopic procedures, irrigating fluids are used for removing blood and pieces of resected tissue from the operation field. To minimize hemolysis after possible fluid absorption, these solutions always contain solutes such as mannitol and sorbitol to reduce their hypo-osmolality (1)(2). Concentrations of these polyols have been determined in blood plasma of patients undergoing transurethral resection of the prostate (3) as a measure of fluid absorption, which may lead to the feared transurethal resection syndrome, involving symptoms such as transient deterioration of mental status, nausea, vomiting, confusion, and arterial hypotension (4).For gas chromatographic analysis, polyols are better separated as n -butyldiboronate derivatives (3)(4)(5) than as trimethylsilyl derivatives, and the derivatization procedure is less time consuming than is formation of acetyl derivatives. Nevertheless, gas chromatographic methods using flame ionization detection show poor detection limits and, as an additional restriction, interference from other polyols (5).We reinvestigated the determination of mannitol and sorbitol in serum with gas chromatography–mass spectrometry by using n -butyldiboronate derivatives (5)(6). Whereas reported methods use zinc sulfate/barium hydroxide precipitation for deproteinization of samples, we found that absolute values of peak areas were <70% of those obtained by untreated samples, likely caused by analyte absorption on insoluble residues of precipitation reagents after evaporation. By contrast, with ethanol precipitation avoiding insoluble residues and reducing evaporation time, absolute values were 90–100% and recovery (related to the internal standard) was 89–103% for …