A new approach for determination of urinary 8-hydroxy-2′-deoxyguanosine in cancer patients using reinforced solid/liquid phase microextraction combined with HPLC-DAD

The concentration level of urinary 8-hydroxy-2′-deoxyguanosine (8-OHdG), an oxidative stress biomarker for various diseases especially cancer, has been attracted as a pathway suitable for diagnostic purposes. Determination of urinary 8-OHdG is challenging due to its low level within a complex matrix. In this study, a new approach of solid/liquid phase microextraction technique prior to high-performance liquid chromatography diode-array detection (HPLC-DAD) analysis was developed for the determination of trace levels of 8-OHdG in urine samples. The solid/liquid phase microextraction device was constructed by reinforcement of multi-walled carbon nanotubes into the pores of a short segment 2.5 cm of hollow fiber microtube with two ends heat sealed. Based on the optimized procedure, the selected analyte was extracted from an acidic sample solution (10 mL adjusted at pH = 5) into the five extraction devices. After the extraction period (30 min), the 8-OHdG was eluted from the extraction device using methanol (350 µL) under ultrasonication for 5 min. The analytical performance of the method in synthetic urine samples showed good linearity (R2 > 0.999) with the limits of detection of 0.85 ng mL−1, and extraction recovery > 92.36%. The developed microextraction technique exhibited a confident sensitivity, feasible operation, and simplicity in comparison with other published methods and was valid to determinate trace 8-OHdG in urine cancer patients' samples by using a cheap and commonly available HPLC-DAD instrument.