Improved Sample Preparation Using Packed-Fiber Solid Phase Extraction in the Determination of Urinary P-Cresol

A high-performance liquid chromatographic method (HPLC) for the analysis of p-cresol in urine was developed. After comparing the adsorption efficiencies of three nanofibers, polystyrene nanofiber (PS), polystyrene-FeCl3 nanofiber (PS-FeCl3), and polypyrrole nanofiber (PPY), PPY was used as the sorbent packed in a little column for the extraction of p-cresol in urine. Prepared by packed-fiber solid-phase extraction (PFSPE), urinary free p-cresol was concentrated on PPY sorbents and then desorbed by methanol. The eluent was injected and analyzed by HPLC with ultraviolet detection. The linearity of the proposed method ranged from 0.2 to 300 mu g/mL (r(2) = 0.995). The limit of detection (LOD) at signal-to-noise ratio of 3 was 0.1 mu g/mL. The limit of quantification (LOQ) at signal-to-noise ratio of 10 was 0.35 mu g/mL. The intra-day imprecision and inter-day imprecision was 3.9-6.5% and 4.6-8.8%, respectively. Recoveries were 95.7-97.3%. The novel method was rapid, convenient and reliable. Its application was displayed by the determination of urinary p-cresol in autism spectrum disorder (ASD) children and typical developing children, suggesting a significant increase of urinary p-cresol in children with ASD.