Ultrasensitive and selective spectrofluorimetric determination of S-nitrosothiols by solid-phase extraction

This present work describes the ultrasensitive and selective spectrofluorimetric determination of S-nitrosothiols by solid-phase extraction based on a novel adsorbent TiO(2)-graphene nanocomposite. 1,3,5,7-Tetramethyl-2,6-dicarbethoxy-8-(3,4-diaminophenyl)-difluoroboradiaza-s-indacence is used as fluorescent probe for S-nitrosothiols label. The procedure is based on the fluorescent probe selective reaction with S-nitrosothiols to form highly fluorescent product, its extraction to the TiO(2)-graphene-packed SPE cartridge and spectrofluorimetric determination. The experimental variables affecting the extraction procedure, such as the type of the eluent and its volume, sample pH, and sample volume, have been studied. Under the optimized extraction conditions, the method showed good linearity in the range of 0.5-100 nM. The limit of detection was 0.08 nM (signal-to-noise ratio=3). Relative standard deviation was 2.5%. The developed method was applied to the determination of S-nitrosothiols in human blood samples with recoveries of 92.0-104.0%. This work revealed the great potentials of TiO(2)-graphene as an excellent sorbent material in the analysis of biological samples.