| Summary: | 碩士 === 靜宜大學 === 化粧品科學系 === 104 === The study demonstrated the application of pre-anodized screen-printed carbon ring-disk electrode coupled with a flow injection analysis (FIA) system to determine two cosmetic ingredients: hydroquinone (HQ) and zinc phenolsulfonate (ZPS). This study divided into two parts, the first part is quantity of hydroquinone. From the results of the voltammogram, it was observed that pre-anodized could improve detection hydroquinone either oxidized or reduced sensitivity, and it can detect HQ both oxidation and reduction signals at the same time when HQ flowing through the electrode surface. Additionally, the interference experiments were also verified by calculating redox ratio. The analytical results indicated that the linear range between 0.25 mgL-1 to 160 mgL-1 with a correlation coefficient (R2) of 0.999, and the limit of detection (LOD, S/N = 3) was 0.024 mgL-1. At the same time, real samples were also tested, appreciable recovery was obtained and ranging from 97.76 % to 103.74 %. The second part of this study is the analysis of zinc phenolsulfonate, ZPS at 1.5 V has oxidation current, but found that the detection of oxidation signal showed matrix interferences at a high oxidation potential (1.5 V). Therefore, it can be successfully applied to detect intermediate product reduction signal at a low reduction potential (0.1 V). The results showed that the linear range was from 1 mgL-1 to 160 mgL-1 with a correlation coefficient (R2) of 0.9997, and the detection limit was 0.076 mgL-1 (S/N = 3). Finally, on the real samples were tested, the recovery ranging from 99.54 % to 104.37 %. The above two methods are able to meet the high sensitivity and stability. At the same time it can also be applied to detection of a commercially available product samples and it gives excellent recovery.
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