Screen-printed carbon electrodes modified with cobalt phthalocyanine for selective sulfur detection in cosmetic
Pei-Yen Chen1, Chin-Hsiang Luo, Mei-Chin Chen
1Department of Cosmetic Science, Providence University 200 Chungchi Rd., Taichung 43301, Taiwan; E-Mails: pychen2@pu.edu.tw (P.-Y.C.); s9624065@pu.edu.tw (M.-C.C.); tftsay@pu.edu.tw (F.-J.T.); nfchang@pu.edu.tw (N.-F.C.).
Abstract:
Cobalt phthalocyanine (CoPc) films were deposited on the surface of a screen-printed carbon electrode using a simple drop coating method. The cyclic voltammogram of the resulting CoPc modified screen-printed electrode (CoPc/SPE) prepared under optimum conditions shows a well-behaved redox couple due to the (Co(I)/Co(II)) system. The CoPc/SPE surface demonstrates excellent electrochemical activity towards the oxidation of sulfur in a 0.01 mol·L(-1) NaOH. A linear calibration curve with the detection limit (D(L), S/N = 3) of 0.325 mg·L(-1) was achieved by CoPc/SPE coupled with flow injection analysis of the sulfur concentration ranging from 4 to 1120 mg·L(-1). The precision of the system response was evaluated (3.60% and 3.52% RSD for 12 repeated injections), in the range of 64 and 480 mg·L(-1) sulfur. The applicability of the method was successfully demonstrated in a real sample analysis of sulfur in anti-acne creams, and good recovery was obtained. The CoPc/SPE displayed several advantages in sulfur determination including easy fabrication, high stability, and low cost.
