Comparative Study of the Determination of Parabens in Shampoos by Liquid Chromatography with Amperometric and Coulometric Detection |
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Authors: | Kazuo Murakami Hayaki Watanabe Tsuyako Tateno Jean‐Michel Kauffmann |
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Institution: | 1. Tokyo Kasei University, Faculty of Domestic Science, 1‐18‐1, Kaga, Itabashi, Tokyo 178‐8602, Japan;2. Université Libre de Bruxelles, Pharmaceutical Institute, Campus Plaine, CP 205/6, Boulevard du Triomphe, 1050 Bruxelles, Belgium tel.:+32?2?6505215;3. fax+32?2?65055225 |
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Abstract: | The simultaneous determination of four para‐hydroxybenzoic acid esters (parabens) in shampoos was studied by liquid chromatography (LC) with amperometric (LC‐AD) and coulometric (LC‐CD) detection. The parabens were separated on an ODS C18 reversed column by isocratic elution with a mobile phase based on methanol‐0.1 M acetic acid (60 : 40%, v/v) with 0.02 M NaClO4 at a flow rate of 0.8 mL min?1. The limit of detection (S/N>3) for the analytes was in the 15–25 pg (injected mass) range at an applied potential of 1.20 V vs. Ag/AgCl using the LC‐AD and in the 2–3 pg range at a potential of 0.790 V vs. Pd using the LC‐CD. The peak ratio of the internal standard peak (IS: 4‐hydroxybenzoic acid sec‐butyl ester) versus the analyte peak was found to be related to the amount injected from 0.1 ng to 100ng (r=0.996–0.999) with the LC‐AD and from 0.050 ng to 100 ng range (r=0.999–1.000) with the LC‐CD. The relative standard deviation (RSD, n=10) was comprised between 1.8 to 3.5% by LC‐AD ( 5 ng injected) and between 2.0 to 2.4% by LC‐CD (0.5 ng injected). The determination of four most used parabens in ten different shampoos was successfully realized. |
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Keywords: | 4‐Hydroxybenzoic acid esters Shampoos Parabens Electrochemical detection Liquid chromatography |
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