Nanofibers comprising polystyrene and zinc acetate for extraction of salivary histidine prior to its determination by HPLC-DAD.

Abstract

Anovel nanofiber-based solid phase extraction(NFSPE)coupled with HPLC-DAD was developed for the determination of salivary histidine, a new potential index of physiological events. Thetreatment of the samplewas based on a coupling reaction of histidinewith the diazotization products of sulfanilic acid and sodium nitritein a slightly alkaline medium,followed byNFSPE.Nanofibers comprising polystyrene and zinc acetate were used as a novelsolid-phasesorbent to extract derived histidine via the chelation of Zn2+with the imidazole group in the analyte. The eluted target compound was analyzed by HPLC-DAD. Goodlinearity was achieved with the concentrations of histidine ranging from 0.645 to 64.5µM; the detection limit was 0.193µM. Theintra-day and inter-day coefficients of variation were less than 8.0%.The method was successfully applied tothe determination of salivary histidine in the subjects exposed to a public speaking stress.