Simple analysis of naphthalene in human whole blood and urine by headspace capillary gas chromatography with large-volume injection

Abstract

A very simple method for analysis of naphthalene in human whole blood and urine by headspace gas chromatography (GC) is presented. It does not require solid-phase microextraction or cryogenic trapping devices, but needs only a conventional capillary GC instrument with flame ionization detection. The advantage of the method is that as much as 5 ml of headspace vapor can be injected into a GC instrument in splitless mode for sensitive detection. After heating a diluted whole blood or urine sample containing naphthalene and 1-methylnaphthalene (internal standard, IS) in a 7.0-ml vial at 80°C for 30 min, 5 ml of the headspace vapor was drawn with a glass syringe and injected into the gas chromatograph. Before injection, the column temperature was set at 50°C to trap the analytes, and then the oven temperature was programmed up to 300°C. Sharp peaks were obtained for both analyte and IS, and only a few impurity peaks appeared, which did not interfere with the test peaks, mainly for whole blood samples. The detection limit (signal-to-noise ratio. 3) were about 0.05 and 0.01 μg/ml for whole blood and urine, respectively. Precision and linearity were also examined to confirm the reliability. Such a simple headspace GC technique with large-volume injection will be applicable to other low-volatility compounds in biological matrices, and will be useful in forensic toxicological analysis.