Abstract: Explosives are widely used around the world annually. Continuous measurement of explosives is not only for military purposes (i.e. production of weapons) and mining activities. These are used in many security gate to decrease terrorist activities [1]. Otherwise improper handling, production, storage and decommissioning of the poly nitro aromatic explosive especially 2,4,6-trinitrotoluene(TNT) has led to extensive contamination of soil and groundwater and this is too dangerous and toxic for human, animals, plants and other microorganisms[3-4]. The important hazards of this material is easily absorbed through the skin. They can cause the formation of methemoglobin on acute exposures and anemia on chronic exposures. TNT is one of the explosive compounds which is widely used for military purposes and in the mining sector. Due to the significant detrimental effects, contamination of soil and groundwater with TNT is the major concern. Driven by the need to detect trace amounts of TNT in environmental samples, this research demonstrates a rapid, sensitive and low cost method to determinate this compound. In this study, L-cysteine used as a bio-indicator for selective identification of TNT. L-Cysteine is an amino acid that can form a meisenheimer complex with TNT and change the color of TNT solution from colorless to red.The increasing use of smart phones and the other hand, development of tools and accessories such as digital cameras, led us to use this tool as a portable utility to identify and determinate desired compounds. Quantitative analysis of TNT was achieved using an innovative application of camera-phone where the relationship between the Red Green Blue (RGB) value of the red meisenheimer complex and concentration of TNT was exploited. Some influencing factors in the proposed method, such as basicity of the sample, concentration of L-cysteine and… were simultaneous optimized using multivariate experimental design. The wide linear range (1-50µg ml-1) and low detection limit(0.25 µg ml-1) achieved were comparable with those from spectrophotometric quantification methods. The results indicated that smart phones can have a good performance in fast and accurate testing and more development in their accessories always allows human to have a mobile laboratory in his pocket. The second and main benefit is utilizing of non-toxic bio-indicator based on L-cysteine (an edible amino acid) in aqueous solution.

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