Paper-based solid-phase microextraction for analysis of 8-hydroxy-2'-deoxyguanosine in urine sample by CE-LIF.

An easy-to-do paper-based solid-phase microextraction (p-SPME) was developed for determination of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in urine sample by CE-LIF. Small piece of filter paper was used as a solid phase to extract 8-OHdG from urine sample. Its primary mechanism is based on the hydrogen-bonding interaction between 8-OHdG and cellulose molecules. The effects of the pH of the sample solution, extraction time, and temperature on the peak area of the analyte were investigated in order to obtain the optimal p-SPME conditions. Comparing with the untreated sample, the p-SPME can significantly reduce the interference to the separation of 8-OHdG by CE-LIF. Meanwhile, the p-SPEM can provide more than three times concentrated effect. The developed method was evaluated according to an FDA guideline for biological analysis. The precisions (RSD%, n = 5) of the peak area and migration time of the analyte at three different concentrations were within 3.02-5.82% and 0.92-1.58%, respectively. The limit of identification of the method is about 5 nM according to the significant difference between two sets of the samples with and without spiking the standard (Student's t-test, p < 0.05). Good linearity was obtained in the range of 10-1000 nM (R2 >0.99) based on the standard addition. The recoveries at three different concentrations were within 99.8-103.5%. The results of the real sample analysis are consistent with those reported in our previous paper (Electrophoresis 2014, 35, 1873-1879).