Application of packed-fiber solid-phase extraction coupled with GC-MS for the determination of short-chain fatty acids in children's urine.

BACKGROUND: Autism spectrum disorder (ASD) is a complex disorder involving interactions between genetic, epigenetic and environmental factors. Gastrointestinal (GI) disorders are prevalent in the cohort of children with ASD and they have been recognized as a comorbid condition recently. It is of value to monitor GI issues in individuals, and to help further characterize factors that may contribute to GI disorders (in individuals with and without ASD). Due to the biological relevance of short-chain fatty acids (SCFAs) to GI disorders, it is important to develop a rapid and selective detection method capable of identifying and quantifying SCFAs in complex biological samples. Because of low concentration and hydrophilicity of SCFAs, the pretreatment of sample becomes the key step to detection method. We erected and verified a packed-fiber solid-phase extraction (PFSPE) based on Polypyrrole (PPY) nanofibers coupled with gas chromatography-mass spectrometry (GC-MS) to determine SCFAs in urine. The proposed method was applied to detect SCFAs in urine from children with and without ASD, and the results between the 2 groups was compared.

METHODS: PFSPE method was utilized for the direct pretreatment of SCFAs in urine from children. The SCFAs extracted on nanofibers was subsequently eluted with hydrochloric acid ethanol solution and detected by GC-MS.

RESULTS: Intraday and interday assay CVs were ≤10%, and the recoveries was 82.6%-110.5%. Limit of detection (LOD) and limit of quantification (LOQ) were 0.25-2.67ng/ml and 0.85-8.97ng/ml, respectively. The level of SCFAs in urine from children with ASD were significantly higher than that from control group.

CONCLUSION: The proposed method improves the simplification of sample treatment and displays sufficient analytical sensitivity and selectivity. The assay offers a potential to monitor the SCFAs in urine in clinical and experimental investigation of ASD.