[Simultaneous determination of seven naphthalenediols in cosmetics by reversed-phase high performance liquid...

A novel analytical method for the simultaneous determination of seven naphthalenediols (2,6-naphthalenediol, 1,5-naphthalenediol, 1,6-naphthalenediol, 2,7-naphthalenediol, 1,7-naphthalenediol, 1,3-naphthalenediol and 2,3-naphthalenediol) in cosmetics by reversed-phase high performance liquid chromatography (RP-HPLC) with a diode array detector was established. The moisturizer, cream, emulsion and water-like cosmetic samples were extracted with 95% ethanol (v/v), and the powder-like cosmetic samples were extracted with 95% ethanol-0.1% acetic acid (3: 2, v/v), then the extracts were centrifuged, filtrated, and analyzed by RP-HPLC using a C18 column, employing methanol-0.1% acetic acid aqueous solution as the mobile phases under the condition of gradient elution. The naphthalenediols were qualitatively determined by retention times, and confirmed by ultraviolet spectra. The external standard method was applied for the quantification. The results indicated that the limits of quantification (LOQs) of the seven naphthalenediols were ranged from 0.5 mg/kg to 1.2 mg/kg (S/N = 10); meanwhile, the linear correlation coefficients of them were all no less than 0.999 0 within the linear ranges. Their recoveries in spiked samples at the levels of 5.0 - 50 mg/kg were ranged from 84.0% to 102% with the relative standard deviations (RSDs) of 1.3% - 5.7% (n = 6). The method is simple, precise and suitable for the determination of naphthalenediols in cosmetic samples.