Post-derivatization procedure for determination of hippuric acid after extraction by an automated micro solid phase extraction system and monitoring by gas chromatography

A rapid, simple and high sensitive method is described here for extraction of hippuric acid (HA) from human urine samples by using an automated micro solid phase extraction system (μ-SPE). However in order to increase sensitivity of gas chromatography with flame ionization detector, a post derivatization procedure was developed. In this work, a polypyrrole was synthesized by chemical oxidation of the pyrrole monomer in non-aqueous solution and applied as an excellent and efficient sorbent for μ-SPE. The calibration curves were linear in the range of 0.018–8.95 μg mL−1 for HA, in both water and urine samples with correlation coefficients 0.9973 and 0.9946, respectively; limits of detections were 12.1 ng mL−1 and 16.5 ng mL−1, respectively. This method was successfully used to analyze trace amounts of HA in human urine samples without any interference from coexisting substances.