Deteksi Kurkumin dan Bisdemetoksikurkumin dengan Teknik Voltammetri Menggunakan Elektrode Boron-Doped Diamond

Abstract

Pada penelitian ini metode deteksi kurkumin dan bisdemetoksikurkumin dikembangkan dengan teknik voltammetri siklik menggunakan elektrode boron-doped diamond. Voltammogram siklik kurkumin dan bisdemetoksikurkumin dalam larutan elektrolit tetrabutilamonium heksafluorofosfat (TBAPF₆)-asetonitril masing-masing menunjukkan 2 puncak oksidasi, yaitu pada potensial +0,4 V dan +1,9 V vs. Ag/AgCl untuk kurkumin, serta +0,6 V dan +2,0 V vs. Ag/AgCl untuk bisdemetoksikurkumin. Hubungan linear diperoleh antara konsentrasi kurkumin maupun bisdemetoksikurkumin dengan arus puncak oksidasinya. Hubungan linear  yang diperoleh adalah I(µA) = 8619,9C (M) + 0,7285 (R²=0,9995) dan I(µA) = 14658C (M) + 16,388 (R²=0,9299) berturut-turut untuk kurkumin puncak pertama dan kedua, serta I(µA) = 7953,2C (M) + 5,3977 (R²=0,9871) dan I(µA) = 5807,7 C (M) + 7,7616 (R²=0,9981) untuk bisdemetoksikurkumin puncak pertama dan kedua. Aplikasi metode yang dikembangkan terhadap sampel buatan yang mengandung campuran kurkumin dan bisdemetoksikurkumin menghasilkan 3 puncak oksidasi pada potensial +0,3 V, +1,2 V, dan +2,0 V vs Ag/AgCl mengindikasikan terjadinya tumpang tindih antara puncak kurkumin dan BDMC serta pergeseran puncak oksidasi. Nilai presisi pengukuran dengan metode yang dikembangkan ialah 15,86 dan 15,15% untuk kurkumin, serta 9,85 dan 31,47% untuk bisdemetoksikurkumin. Sementara nilai akurasi pengukuran ialah sebesar 96,69 dan 125,36% untuk kurkumin, serta 97,95 dan 127,54% untuk bisdemetoksikurkumin masing-masing berdasarkan puncak 1 dan 2. Hasil yang diperoleh menunjukkan performa analitik metode yang dikembangkan masih perlu ditingkatkan sebelum diaplikasikan untuk analisis kuantitatif.

Detection of Curcumin and Bisdemetoxycurcumin by Voltammetric Technique using a Boron-Doped Diamond Electrode.  This study develops a cyclic voltammetry method for simultaneous detection of curcuminoid by using boron-doped diamond electrode. Curcumin and bisdemethoxycurcumin (BDMC) in tetrabutylammonium hexafluorophosphate (TBAPF₆)-acetonitrile as electrolyte solution showed two oxidation peaks at +0.4 V and +1.9 V for curcumin, while those for BDMC appeared at +0.6 V and +2.0 V. Reduction peaks of both standards were not observed. In the optimum conditions, this method showed linear correlation between concentration of curcumin and BDMC with it’s oxidation peak current. The equations of I(µA) = 8619.9(C) (M) + 0.7285 (R²=0,9995) and I(µA) = 14658(C) (M) + 16.388 (R²=0.9299) were obtained for curcumin, I(µA) = 7953.2(C) (M) + 5.3977 (R²=0,9871) and I(µA) = 5807.7(C) (M) + 7.7616 (R²=0.9981) for BDMC. Meanwhile, the measurement of the artificial samples containing a mixture of curcumin and BDMC showed three oxidation peaks at +0.3 V, +1.2 V, and +2.0 V. This result indicated an overlapping between curcumin and BDMC peaks and peak shifting. Precision of the developed method was expressed as percent RSD, giving value of 15.86 and 15.15% for curcumin, and 9.85 and 31.47% for BDMC. The accuracy was 96.69 and 125.36% for curcumin, meanwhile for BDMC was 97.95 and 127.54% for peak 1 and 2. The result indicated that the method required further improvement before applied for quantitative analysis.