Development of a SBSE-HPLC method using sol-gel based germania coated twister for the analysis of 4-chloro-1-naphthol in biological and water samples

In this work, 4-chloro-1-naphthol is extracted from environmental and biological samples using germania-based polydimethylsiloxane hybrid organic-inorganic coated twister, followed by high-performance liquid chromatography-ultraviolet detection. The coated twisters showed a good preparation reproducibility of 1.7% (n = 3) for one batch and 3.5% (n = 3) for different batches. The coated stir bars were successfully characterized using field emission scanning electron microscope, energy dispersive X-ray spectroscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. Sample volume, extraction time, stirring rate, desorption solvent, desorption time and ionic strength were optimized for the stir bar sorptive extraction process. Under optimized experimental conditions, the method showed linearity in the range of 0.4–800 ng mL⁻¹ with R² = 0.9992 and limit of detection (S/N = 3) as 0.034 ng mL⁻¹. The chromatographic method showed higher selectivity by having baseline separation between 1-naphthol and 2-naphthol (the expected interference) and 4-chloro-1-naphthol. This germania-based stir bar sorptive extraction-high performance liquid chromatographic method was successfully applied for 4-chloro-1-naphthol in wastewater, pool water, and human urine and showed relative recoveries between 87.4 and 141.3% with acceptable relative standard deviation i.e. 4–11%.