Synchronous fluorescence determination of urinary 1-hydroxypyrene, β-naphthol and 9-hydroxyphenanthrene based on the sensitizing effect of β-cyclodextrin

Abstract

A novel method for the simultaneous determination of 1-hydroxypyrene (1-OHP), β-naphthol (β-NAP) and 9-hydroxyphenanthrene (9-OHPe) in human urine has been established by using synchronous fluorescence spectrometry. It was based on the fact that synchronous fluorescence spectrometry can resolve the broad-band overlapping of conventional fluorescence spectra, which arise from their similar molecular structures. Only one single scan is needed for quantitative determination of three compounds simultaneously when Δ λ = 15 nm is chosen. The signals detected at these three wavelengths, 369.6, 330.0 and 358.0 nm, vary linearly when the concentration of 1-OHP, β-NAP and 9-OHPe is in the range of 2.16 × 10 −8–1.50 × 10 −5 mol L −1, 1.20 × 10 −7–1.10 × 10 −5 mol L −1 and 1.07 × 10 −7–3.50 × 10 −5 mol L −1, respectively. The correlation coefficients for the standard calibration graphs were 0.994, 0.999 and 0.997 ( n = 7) for 1-OHP, β-NAP and 9-OHPe, respectively. The limits of detection (LOD) for 1-OHP, β-NAP and 9-OHPe were 6.47 × 10 −9 mol L −1, 3.60 × 10 −8 mol L −1 and 3.02 × 10 −8 mol L −1with relative standard deviations (R.S.D.) of 4.70–6.40%, 2.80–4.20%, 3.10–4.90% ( n = 6), respectively. The method described here had been applied to determine traces of 1-OHP, β-NAP and 9-OHPe in human urine, and the obtained results were in good agreement with those obtained by the HPLC method. In addition, the interaction modes between β-cyclodextrin (β-CD) and 1-OHP, β-NAP or 9-OHPe, as well as the mechanism of the fluorescence enhancement were also discussed.