Dioscorea Alata L anthocyanin methanol extract as a potential optical active pH sensitive compound Eka Safitri (a), Hani Humaira (a), Nazaruddin (a), Susilawati, Murniana (a) and Nor DiyanaMd Sani (b)
a) Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Syiah Kuala, Banda Aceh 23111, Indonesia *e.safitri[at]unsyiah.ac.id
b) Sanichem Resources Sdn. Bhd. No 7 & 7A Jalan Timur 6/1A Mercato Enstek, Bandar Estek 71060, Negeri Sembilan, Malaysia (b)
Abstract
Anthocyanin from Dioscorea alata L has been successfully extracted using methanol solvent and has been tested for its sensitivity towards pH change in citrate and phosphate buffer solutions using a UV-Vis spectrophotometer. The extracted anthocyanin tested positive for the presence of flavonoid and phenol. The total yield of crude extract was 1.63% corresponding to 3.34 x 10-7 M or 16.72 mg/kg dried sample. The maximum absorption against citrate buffer at wavelength 600 nm produced a linear range from pH 4 to 8, with sensitivity = 0.121 and R2 = 0.98. In addition, the maximum absorption for phosphate buffer occurs at wavelength 590 nm with a response linear range of pH 6 to 8 and sensitivity = 0.296 (R2 = 0.97) The optimum buffer concentration for both citrate and phosphate buffer solutions are 0.1M and 0.075 M respectively. The extracted anthocyanin showed a stable response against citrate and phosphate buffer for 140 minutes. Therefore, the extracted anthocyanin can be potentially used as an active substance to develop an optical pH sensor and biosensor based on pH change.
Keywords: Dioscorea alata L ; pH; pH active compound
