BioChip J. (2012) 6(1): 34-40 DOI 10.1007/s13206-012-6105-8 Abstract A rapid and reliable analysis of toxins is prerequisite for food control and human healthcare. Here we demonstrate a simple and multiplexed assay of aflatoxins using time-of-flight secondary ion mass spectrometry (TOF-SIMS). By simply adsorbing either a single analyte or mixed ones onto a gold substrate, the corresponding secondary molecular ions ([M+ H] + ) were clearly observed in a single mass spectrum. As a result of concentration-dependent peak intensity, quan- titative and multiplexed analysis of different aflatoxin analogs from corns was accomplished with immuno- affinity column and TOF-SIMS analysis, which show- ed a good correlation with HPLC data. The detection sensitivity was estimated to be as low as 10 ng mL 폭1 . This approach presented here will find a wide applica- tion to detection of low-levels of toxins in a rapid and multiplexed way. Keywords: Aflatoxin, TOF-SIMS, Quantification, Mul- tiplexed analysis Introduction Aflatoxins are toxic secondary metabolites produced mainly by the fungal species such as Aspergillus flavus and Aspergillus parasiticus that contaminate a wide range of foods and animal feedstuffs stored under tem- perature and humidity conditions favorable to fungal growth 1,2 . There are different kinds of aflatoxins, and aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2), are commonly found in both food and feed. These fungal toxins not only have been considered as potent carcinogens that are extremely hazardous to human liver, but also their chronic effects at low levels of exposure have been of great concern because this results in the decrease of host resistance to infectious diseases 3 . Thus, it is essen- tial to develop a rapid and reliable method for detect- ing the levels of multiple aflatoxins in a variety of foods for human health. Common established methods for assaying aflatox- ins include thin-layer chromatography (TLC) 4 , high performance liquid chromatography (HPLC) 5,6 , and enzyme-linked immunosorbent assay (ELISA) 7-9 . These methods have excellent sensitivities, but they typically require extensive sample pretreatment and time-con- suming operation due to the need of extraction and cleanup procedures. In addition, they lack the ability to perform simultaneous analysis of different kinds of aflatoxins. As an effective approach, the use of matrix- assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-MS) using a UV-absorbing ionic liquid matrix was reported for multiplex and high- throughput screening of aflatoxins 10 . Nonetheless, it still requires a suitable matrix that might interfere with the accurate analysis particularly when the analyte is at a low concentration. In recent, time-of-flight secon- dary ion mass spectrometry (TOF-SIMS) has drawn attention because it allows direct surface identification of intrinsic and unlabeled small molecules (/1,000 Original Research Sensitive and multiplexed analysis of aflatoxins using time-of-flight secondary ion mass spectrometry Jang-Hyuk Ahn 1,† , Young-Su Jeong 2,† , Tae Geol Lee 3 , Young-Pil Kim 4 & Hak-Sung Kim 2 Received: 26 October 2011 / Accepted: 29 November 2011 / Published online: 20 March 2012 � The Korean BioChip Society and Springer 2012 1 Food Safety Center, R&D Institute, Namyang Dairy Co., Ltd., Gongju 314-914, Korea 2 Department of Biological Sciences, KAIST, Daejeon 305-701, Korea 3 Center for Nano-Bio Convergence, Korea Research Institute of Standards and Science (KRISS), Daejeon 305-600, Korea 4 Department of Life Science, Hanyang University, Seoul 133-791, Korea † These authors contributed equally to this work. Correspondence and requests for materials should be addressed to Y.-P. Kim ( ypilkim@hanyang.ac.kr) and H.-S. Kim ( hskim76@kaist.ac.kr)