Analysis of volatile organic compounds in human urine by headspace gas chromatography-mass spectrometry with a multipurpose sampler

Abstract

A multipurpose sampler (Gerstel MPS), designed for liquid large volume, gaseous and headspace samples was used for the GC-MS analysis of organic volatiles in human urine. Headspace sampling with a volume-, temperature- and speed-controlled gas-tight syringe was combined with a temperature-controlled cold injection system (CIS) for cold trapping, enrichment and focusing of analytes. Regular 2-ml GC vials filled with 1 ml acidified urine were used as headspace sampling vials. A 100-vial autosampler tray was equipped with an additional temperature and heating time controlled "preheating station" for five vials. Profiles of organic volatiles in human urine were determined and 34 components identified. Trimethylamine (TMA) and 4-heptanone as two metabolites of medical interest were quantified. Calibration curves and intra assay imprecision for 4-heptanone concentrations in the range of 40 to 800 ng/ml showed a correlation coefficient of r = 0.9980 and a relative standard deviation (RSD) between 3.0 and 3.4%. Calibration curves and intra-assay imprecision for TMA concentrations in the range of medical interest from 0.5 to 20 micrograms/ml showed a correlation coefficient of r = 0.9968 and a RSD between 4.1 and 6.8%. The high practicability of the multipurpose sampler for both gaseous and liquid samples together with the here shown good reproducibility and sensitivity make this single CIS-GC-MS system very attractive for routine clinical use in metabolic profiling of organic volatiles (headspace) and non-volatiles (liquid).