Inorganic–organic hybrid coating material for the online in‐tube solid‐phase microextraction of monohydroxy polycyclic aromatic hydrocarbons in urine

An inorganic–organic hybrid nanocomposite (zinc oxide/polypyrrole) that represents a novel kind of coating for in‐tube solid‐phase microextraction is reported. The composite coating was prepared by a facile electrochemical polymerization strategy on the inner surface of a stainless‐steel tube. Based on the coated tube, a novel online in‐tube solid‐phase microextraction with liquid chromatography and mass spectrometry method was developed and applied for the extraction of three monohydroxy polycyclic aromatic hydrocarbons in human urine. The coating displayed good extraction ability toward monohydroxy polycyclic aromatic hydrocarbons. In addition, long lifespan, excellent stability, and good compression resistance were also obtained for the coating. The experimental conditions affecting the extraction were optimized systematically. Under the optimal conditions, the limits of detection and quantification were in the range of 0.039–0.050 and 0.130–0.167 ng/mL, respectively. Good linearity (0.2–100 ng/mL) was obtained with correlation coefficients larger than 0.9967. The repeatability, expressed as relative standard deviation, ranged between 2.5% and 9.4%. The method offered the advantage of process simplicity, rapidity, automation, and sensitivity in the analysis of human urinary monohydroxy polycyclic aromatic hydrocarbons in two different cities of Hubei province. An acceptable recovery of monohydroxy polycyclic aromatic hydrocarbons (64–122%) represented the additional attractive features of the method in real urine analysis.