Inorganic arsenic contamination has caused a remarkable impact on the contamination of soil and groundwater in many countries. Consequently, determination of inorganic arsenic on site is very crucial especially arsenic (III) which is more toxic than arsenic (V). Thus, a more rapid, simple and ecofriendly approach was developed in this study to determine arsenic (III) by incorporation of image processing technique into colorimetric method. The effects of various factors were evaluated by a 2 4 full factorial design with a blocking factor. The mass ratio of sulfamic acid to zinc powder was the most significant factor affected red, green and blue (RGB) color values and followed by reaction period. The optimum conditions for the detection were found to be using 1 g of sulfamic acid and 0.5 g of zinc powder at 5 minutes. This work also demonstrates that the developed method is able to detect arsenic (III) rapidly and easily.

Arsenic and its derivatives have been used in pharmaceutical products, pesticides, alloying agents, semiconductors and metal adhesives [1]. However, inorganic arsenic compounds are categorized in Group 1 (carcinogenic to humans) by the International Agency for Research on Cancer (IARC) [2]. Arsenic can enter our body either by drinking of contaminated water or by the consumption of plants commonly grown in the contaminated area [3]. Environmental exposure to arsenic causes a huge health problem globally [4]. Various arsenic detection techniques were developed [5]. However, most of these methods have limitations such as interference by a large number of ions, low/moderate sensitivity and require heating or extraction from organic solvents, requirement of sample preservations and chemical reduction steps, which may introduce sample contamination [6]. In addition, the samples are required to be transported to a laboratory for the analysis using a sophisticated analytical instrument. These sophisticated analytical techniques need sample preparation before the analysis, which is found to be tedious, time consuming and more reagents are required [1,7]. Therefore, to overcome these disadvantages, a rapid and simple detection method is required to provide an on-site checking of risk level of source water for drinking use and of effluent from small-scale arsenic removal plants with a rapid

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