Development of gold nanoparticles modified screen-printed carbon electrode for the analysis of thiram, disulfiram and their derivative in food using ultra-high performance liquid chromatography Kanokwan Charoenkitamorn a , Orawon Chailapakul a,c,n , Weena Siangproh b,nn a Electrochemistry and Optical Spectroscopy Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Patumwan, Bangkok 10330, Thailand b Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukhumvit 23, Wattana, Bangkok 10110, Thailand c National Center of Excellent of Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand article info Article history: Received 16 July 2014 Received in revised form 10 September 2014 Accepted 11 September 2014 Available online 30 September 2014 Keywords: Dithiocarbamates Fungicides Screen-printed carbon electrode Gold nanoparticles Simultaneous determination Ultra-high performance liquid chromatography abstract For the first time, gold nanoparticles (AuNPs) modified screen-printed carbon electrode (SPCE) was developed as working electrode in ultra-high performance liquid chromatography (UHPLC) coupled with electrochemical detection (UHPLC-ED) for simultaneous determination of thiram, disulfiram, and N,N-diethyl-N’,N’- dimethylthiuram disulfide, their derivative compound. The separation was performed in reversed-phase mode using C18 column, mobile phase consisting of 55:45 (v/v) ratio of 0.05 M phosphate buffer solution (pH 5) and acetonitrile at a flow rate of 1.5 mL min À1 . For the detection part, the amperometric detection was chosen with a detection potential of 1.2 V vs. Ag/AgCl. Under the optimal conditions, the good linear relationship was obtained in the range of 0.07–15, 0.07–12, and 0.5–15 mg mL À1 (correlation coefficient more than 0.9900) for thiram, N,N-diethyl-N’,N’-dimethylthiuram disulfide, and disulfiram, respectively. The limits of detection (LODs) of thiram, N,N-diethyl-N’,N’-dimethylthiuram disulfide, and disulfiram were 0.022, 0.023, and 0.165 mg mL À1 , respectively. Moreover, this method was successfully applied for the detection of these compounds in real samples (apple, grape and lettuce) with the recoveries ranging from 94.3% to 108.8%. To validate this developed method, a highly quantitative agreement was clearly observed compared to standard UHPLC–UV system. Therefore, the proposed electrode can be effectively used as an alternative electrode in UHPLC-ED for rapid, selective, highly sensitive, and simultaneous determination of thiram, disulfiram, and N,N-diethyl-N’ ,N’- dimethylthiuram disulfide. & 2014 Elsevier B.V. All rights reserved. 1. Introduction Nowadays, the designing of electrochemical sensor has been developed in the field of electrochemistry to improve the analytical efficiency in the terms of sensitivity, selectivity, reliability, ease of fabrication and use, and low cost. Screen printing is the technology used for fabrication of biosensors and chemical sensors instead of using large-scale electrode. Their various advantages such as miniatur- ization, versatility, and low cost of production are really attractive [1]. In addition, many laboratories use the screen-printing for in-house production of sensors. Screen-printed carbon electrode (SPCE) is an alternative material used instead of using the traditional electrodes based on economic substrate. Recently, SPCE have been successfully used as the electrochemical sensor for various researches due to the simplicity to produce and still give the rapid responses [2]. Moreover, the main advantage of SPCE is able to use only once and then is discarded. This advantage can be used to solve the problems of surface fouling compared with those of conventional electrodes. However, the limitation of SPCE is small surface area of working electrode leading to the lack of sensitivity [3]. Therefore, electrode modification is neces- sary to solve this problem. For electrode modification, metal-nanoparticles modified SPCE is focused to improve the electrochemical efficiency. Metal-nanoparticles are attractive catalyst in the electrochemical applications. Transition metals, especially precious metals, show very high catalytic abilities for catalyzing the redox process of some interested molecules, making the use of electroanalytical techniques for applications are extended [4]. Particularly, gold nanoparticles (AuNPs) have received significant attention in recent years. AuNPs are widely used in many fields due to their unique optical and physical properties, such as surface plasmon oscillations for labeling, imaging, and sensing [5]. For the electrochemical fields, AuNPs have been widely used for modification of electrode because of their benefits including catalysis, mass Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/talanta Talanta http://dx.doi.org/10.1016/j.talanta.2014.09.020 0039-9140/& 2014 Elsevier B.V. All rights reserved. n Corresponding author. Tel.: þ662 218 7615. nn Corresponding author. Tel.: þ662 249 5000x18208. E-mail addresses: corawon@chula.ac.th (O. Chailapakul), weenasi@hotmail.com (W. Siangproh). Talanta 132 (2015) 416–423