Determination of cresol isomers and phenol in human body fluids by capillary gas chromatography with cryogenic oven trapping

A new method for determination of o-, m- and p-cresols and phenol in human body fluids by capillary gas chromatography (GC) has been developed using cryogenic oven trapping. After heating a whole blood or urine sample containing the four compounds and 2,4-dimethylphenol as internal standard in a 7.5 mL-vial at 100degreesC for 10 min, 5 mL of headspace vapor was drawn into a gastight syringe. All vapor was introduced through an injection port of a GC instrument in the splitless mode into an alpha-DEX 120 middle-bore capillary column at 0degreesC of oven temperature for trapping the compounds; the oven temperature was programmed up to 170degreesC for their detection by GC with flame ionization detection. The present conditions gave sharp peaks for the compounds, a good separation of each peak and low background impurities for whole blood and urine samples. The regression equations for all compounds showed good linearity in the range of 1-10 mug 0.5 mL(-1), with r values of 0.9983-0.9998, for both samples. The detection limits (signal-to-noise ratio=3) for the compounds were 0.3-0.5 mug 0.5 mL(-1) for whole blood and urine samples. Intra- and inter-day precisions were not greater than 11.6%, for whole blood and urine samples. The data obtained from actual determination of p- and m-cresols in rat whole blood after oral administration of saponaceous cresol solution are also presented.