Optimization of the HS-GC/MS technique for urine metabolomic profiling.

BACKGROUND

Headspace gas chromatography-mass spectrometry (HS GC-MS) traditionally has been applied to analyze samples with a high content of volatile components, such as stool samples. Nevertheless, other types of samples-for example, urine-may also contain volatile compounds and serve as valuable sources of diagnostic information. However, the content of volatile components in urine is considerably lower than in stool samples, necessitating modification of the HS GC/MS method. Such optimization could be particularly valuable for patients with inflammatory bowel disease (IBD), for whom providing a stool sample can sometimes be challenging. The aim of this work was to optimize a method for assessing volatile components in urine samples.

METHODS

Urine samples were collected from 10 patients with IBD and 10 healthy controls. Laboratory, endoscopic, and histopathological analyses confirmed the IBD diagnosis. Metabolomic profiling was performed using HS GC/MS (Shimadzu QP2010 Ultra with HS-20 extractor).

RESULTS

Volatile metabolites in urine samples suitable for analysis were acquired through optimized sample preparation procedures, including sampling vapor with a salt mixture, increasing the sample volume, adjusting the temperature regime during preparation, and fine-tuning the delay time prior to mass spectrometer activation. The most comprehensive and high-quality results were obtained using a triple extraction method with cryo-trap technology. As a result of HS GC/MS method optimization, urine metabolome analysis of IBD patients enabled the identification of biomarkers that can be utilized for the clinical detection of IBD. 2-Heptanone and pentadecane were identified as IBD-associated biomarkers.

CONCLUSIONS

Optimized preparation protocols enable HS GC/MS method to be effectively applied for the analysis of volatile components in urine samples. The modified HS GC/MS method can be scaled up for large-sample analysis to both detect identified metabolites and explore potential new biomarkers associated with IBD and other pathologies.