New methyltrimethoxysilane-(3-mercaptopropyl)- trimethoxysilane coated hollow fiber-solid phase microextraction for hexanal and heptanal analysis

Abstract

Determination of volatile organic compounds (VOCs) in various matrices is often accomplished using solid phase microextraction (SPME) as a superior mode of extraction. Alternatively, another configuration of solid phase microextraction (SPME) namely hollow fiber-solid phase microextraction (HF-SPME) is a great approach to redress some limitations of the ordinary SPME fibers including fiber breakage, coating stripping and sample carry over. The HF-SPME technique highlights the use of hollow polypropylene (PP) membrane to hold and protect the adsorbent inside its lumen. Unlike the conventional SPME, the inexpensive HF device can be disposed after single use. Introducing extracting phase via sol-gel technology has gained great interest owing to its simple preparation method and promising way to obtain materials with good characteristics. In the present work, a new hybrid silica material based on methyltrimethoxysilane-(3-mercaptopropyl)trimethoxysilane (MTMOS-MPTMOS) was introduced as a new extractant of HF-SPME and the effectiveness of the proposed method was tested for analysis of hexanal and heptanal as the target VOC analytes. Preparation of the HF-SPME MTMOS-MPTMOS was simple in which the hybrid material was synthesized via sol-gel method and was self-polymerized in small segments of HF. Parameters affecting the efficiency of the HF-SPME MTMOS-MPTMOS in extracting both aldehydes were thoroughly investigated and analyzed by gas chromatography-flame ionization detection (GC-FID). It was found that the highest efficiency was achieved as the extraction was conducted in 30 min at a stirring rate of 1000 rpm in a 10 mL of sample solution whereby the back-extraction was performed via vortex for 3 min using 100 µL methanol as desorption solvent. Under the optimal conditions, linearity was observed over a range of 0.020-10.00 µg mL-1 with detection limits of 0.015 µg mL-1 and 0.010 µg mL-1 for hexanal and heptanal, respectively. The applicability of the HF-SPME MTMOS-MPTMOS for analysis of hexanal and heptanal in human urine sample was proven from the quantitative recoveries (&gt, 90) achieved. The HF-SPME MTMOS-MPTMOS offers an attractive alternative for rapid and convenient extraction tool and showed good potential for analysis of hexanal and heptanal from aqueous samples.