MWCNT-Modified Gold Electrode Sensor for the Determination of Propyl Gallate in Vegetable Oils
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MWCNT-Modified Gold Electrode Sensor for the Determination of Propyl Gallate in Vegetable Oils Anuja Elevathoor Vikraman & Zafna Rasheed & Leena Rajith & Laina Angamaly Lonappan & Girish Kumar Krishnapillai
Received: 8 May 2012 / Accepted: 20 July 2012 / Published online: 12 August 2012 # Springer Science+Business Media, LLC 2012
Abstract A differential pulse voltammetric method for the determination of the synthetic food antioxidant, propyl gallate (PG) was developed. Determination of PG was carried out using multiwalled carbon nanotube (MWCNT)-modified gold electrode (GE) in a solution of 0.1 M acetate buffer (pH 7) as supporting electrolyte. The developed sensor showed an excellent catalytic activity and stability for PG oxidation. Effect of common interfering ions, amount of MWCNT–Nafion suspension, pH of the supporting electrolyte, and scan rate were studied. Under optimized conditions, PG concentration as low as 6.3 × 10−7 M can be determined in food samples. The determination of PG in vegetable oils with the proposed sensor was in good agreement with those obtained by reported spectrophotometric method. Keywords MWCNT . Gold electrode . Propyl gallate . Vegetable oil . Sensor
Introduction Antioxidants (natural and synthetic) play a significant role in retarding lipid oxidation reactions in food products. Phenolic antioxidants are chemicals commonly added to food and pharmaceutical products to improve their stability, especially to prevent rancidness in products containing lipids or fats (Medeiros et al. 2010; Galeano Diaz et al. 1998). Propyl gallate (PG) suppresses the chain initiation or breaks the chain propagation of the peroxidation of unsaturated A. E. Vikraman : Z. Rasheed : L. Rajith : L. A. Lonappan : G. K. Krishnapillai (*) Department of Applied Chemistry, Cochin University of Science and Technology, Kochi 682 022, India e-mail: [email protected]
fatty acids. Therefore, it is commonly used as an additive in a variety of products, particularly in food, in order to prevent the oxidative damage of fats and oils. These antioxidants appear as preservatives in food stuffs like edible oils, margarine, food concentrates, cookies, etc. (Michalkiewicz et al. 2004). Various studies have shown that antioxidants could enter the human body through the intake of food, pharmaceutical, etc. Recently, people have also found that excessive use of these artificial antioxidants may cause a loss of nourishment and even produce toxic substances to harm people’s health. Therefore, the use of additives is subject to regulations which defines the permitted compounds and their concentration limits (Guan et al. 2006; Gunckel et al. 1998). PG and its related gallates have shown other effects such as inhibition of the respiratory chain of the Trypanosoma cruzi parasite, antimicrobial activity against Escherichia coli, and toxicity to rat hepatocytes due to mitochondrial dysfunction. Moreover, recent results have shown that the antimutagenic properties of some phenolic compounds such as gallates may be due to their inhibiting a
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