Stir bar sorptive extraction of organic dyes from water samples using silica-based sol-gel hybrid adsorbent

The first synthetic dye ‘mauveine’ was discovered in 1856. Since then, other types of synthetic dyes are massively produced and used in several industries including textiles. Even though dyes are not strongly hazardous, they are considered as potential water pollutants due to their solubility in water which are usually high. Some cases reported that they are cytotoxic and carcinogenic to human [1]. The common technique used in the analysis of dyes is solid phase extraction (SPE). It provides a simple and economical analysis compared to liquid-liquid extraction (LLE). However, SPE has some drawbacks which include the production of organic waste, timeconsuming and complex set-up [2]. Therefore, a solventless technique namely stir bar sorptive extraction (SBSE) under the trade name TWISTERTM has been developed to overcome the limitations. However, commercial TWISTERTM is rather expensive and limited in the types of coating materials available. Thus this study attempts to synthesize new adsorbent materials based on silica for use in SBSE. Our successful hybridization of sol-gel materials [3, 4] have led us to the synthesis of another silica-based sol-gel hybrid adsorbent, mercaptopropyltrimethoxysilane-methyltrimethoxysilane (MPTMOS-MTMOS) as sorbent in the analysis of selected organic dyes namely crystal violet, methylene blue and methyl orange in water sample. The use of hybrid material as adsorbent enhanced the ability of the stir bar to extract polar compounds compared to the commercial stir bar [3], and reduced the production cost