Sol-Gel (3-Mercaptopropyl)Trimethoxysilane-Methyltrimethoxysilane as adsorbent for stir bar Sorptive extraction of selected organic dyes

Abstract

A new sol-gel hybrid silica-based (3-mercaptopropyl)trimethoxysilane-methyltrimethoxysilane (MPTMOS-MTMOS) in the ratio of 3:1 was synthesized and applied as an adsorbent in stir bar sorptive extraction (SBSE) of three selected polar organic dyes from water sample. Three organic dyes were used as test analytes namely crystal violet, methyl orange and methylene blue. Analysis of the organic dyes was performed using ultravioletvisible spectroscopy. Optimum extraction conditions was achieved using 50 min extraction time, 240 rpm stirring rate, ultrasonic aided desorption for 15 min using 3 mL methanol and sample solution at pH 4 with addition of 5% (w/v) NaCl. The sol-gel hybrid MPTMOS-MTMOS showed better extraction efficiency (based on absorbance) for the selected organic dyes compared to commercial ethylene-glycol/silicone Twister™ stir bar. Limit of detection obtained was in the range 0.34 -0.75 μg mL-1 (S/N = 3) and linear range achieved was 10 order of magnitude (1.0-10 μg mL-1). The developed sol-gel hybrid material showed high potential as an alternative adsorbent for SBSE of organic dyes. MPTMOS-MTMOS SBSE was successfully applied for simultaneous analysis of three organic dyes from river water with good recovery.