CHINESE JOURNAL OF ANALYTICAL CHEMISTRY Volume 43, Issue 3, March 2015 Online English edition of the Chinese language journal Cite this article as: Chin J Anal Chem, 2015, 43(3), 451–456. ________________________ Received 14 September 2014; accepted 20 November 2014 *Corresponding author. Email: xuxu3426@sina.com Copyright © 2015, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences. Published by Elsevier Limited. All rights reserved. DOI: 10.1016/S1872-2040(15)60813-1 RESEARCH PAPER Flexible Device for Direct Analysis in Real Time without Grid Electrode for Mass Spectrometric Analysis HAN Yu-Liang, ZHANG Yao-Li, YANG Yu-Hui, HUANG Yu-Yu, XU Xu* School of Chemical and Environmental Engineering, Shanghai Institute of Technology, Shanghai 201418, China Abstract: A flexible and simple direct analysis in real-time (DART) device was developed without grid electrode for mass spectrometer injection. It contained inert carrier gas, ionizer, heater and temperature-controller etc. By excluding the grid electrode and then reducing the structure units, the device could be easy to build up in low cost and flexible to connect with a variety of mass spectrometers. Under the optimum experimental conditions including argon carrier gas with a flow rate of 7.5 L min −1 , and heat tape temperature of 300 °C, the device was used to analyze benzene alcohol, linoleic acid, dichlorvos emulsion, mosquito coils, citrus peel, and sample (propranolol hydrochloride) on thin-layer plate combined with mass spectrometer. The results were accurate and showed the device was stable and reliable. Key Words: Direct analysis in real time; Device; Mass spectrometry 1 Introduction Direct analysis in real time (DART) was first developed by Cody group in 2005 [1] as a sample injection unit of mass spectrometer. DART presented the advantages including no sample pretreatment, short analysis time, no adduct ions (M+Na, M+K) produced etc, and was applied in the analysis of harmful substances in the food [2] , crops surface bacteria [3,4] , fake drugs [4] , packaging materials [5,6] , synthetic compounds in mosquito repellent products [7] , plant varieties difference [8] , in which all results were obtained in real time, and no contact and no sample loss. Marinella etc [9] detected the residual harmful composition in the fruit peel directly by DART-MS, in which the limit of detection of imazalil was 1 ng. The work showed that DART-MS technique had high sample throughput, lack of cross contamination between runs, and simplicity. By using DART ionization technique, Fernandez et al [10] identified counterfeit artesunate tablet directly, clearly as commonly excipients of stearate and palmitate with no or little effective antimalarial artesunate composition. Without sample preparation process, ten samples could be analyzed in just two minutes. Hye et al [11] provided a thin layer chromatography (TLC)-DART-MS analysis method for rapid identifying chemical composition in plants. The results showed that TLC-DART-MS was a simple, rapid and efficient method for the research of chemistry component in natural product by real-time high resolution mass spectrometry data of compound components in thin layer plate. Adams et al [12] characterized 16 reference papers in terms of their pulp composition and pitch contaminants by DART-MS, in which the real-time mass spectrograms of bleached kraft, chemithermomechanical, and stone groundwood pulp papers were obtained without extraction, derivatization, separation, and other time- and chemical-consuming sample preparation. The result shows the DART-MS lossless test capacity. Zhang et al [13] identified 8 kinds of tea in situ by DART-MS without sample preparation. In addition, Borges et al [14] analyzed organometallic compounds and Zhao et al [15] analyzed small molecules in plasma using DART-MS method, showing its wide application. However, the existing DART equipments were expensive, complex with difference interface and difficult to install for different mass spectrometer. In this study, a simple, flexible and economic DART device was developed without grid