Monolithic Poly (MAA-Zn/Cr-LDH-EGDMA) Column For In-Tube Solid-Phase Microextraction Of Acidic Herbicides Coupled To GC-MS

So far several sample preparation methods are employed for analyze of chlorophenoxy acetic acids in various matrices [۱]. In-tube solid phase microextraction (IT-SPME) method based on monolithic column, have been developed to overcome difficulties inherent to SPME fibers [۲]. The monolithic columns with proper properties including easy synthesis, higher sorption capacity,۲lower back pressure, faster mass transfer, and good biocompatibility are widely used [۳]. In this work, monolithic poly (methacrylic acid-Zn/Cr-layer double hydroxide-ethylene glycol dimethyl acrylate) column was fabricated in to a polypropylene tube by a facile in-situ polymerization method. The prepared composite was characterized and used as a sorbent for in-tube solid phase microextraction (IT-SPME) method. The method was successfully coupled to GC-MS for extraction and determination of ۲,۴-dichlorophenoxyacetic acid and ۴-chloro-۲-methylphenoxyacetic acid in water samples. According to obtained results, the Zn/Cr-polymer monolithic column shows high sensitivity, good mechanical stability, and high extraction efficiency. Parameters affecting extraction efficiency including the salt concentration, pH of sample solution, extraction time, extraction flow rate, and desorption conditions were optimized. Under optimal conditions, low detection limits in the range of ۰.۰۱–۰.۰۵ μg L−۱, and good linearity in the range of ۰.۱-۵۰۰ μg L−۱ with a correlation coefficient better than ۰.۹۹۷۵ were obtained. The inter- and intra-assay precisions (RSD%, for n = ۳) were in the range of ۷.۱ - ۸.۲% and ۶.۸ -۷.۹ % for ۲,۴-dichlorophenoxyacetic acid and ۴-chloro-۲-methylphenoxyacetic acid, respectively. Also, this method successfully used for extraction and determination acidic herbicides in various real samples.

Keywords:

In-tube solid phase microextraction , Monolithic column , Layered double hydroxide , ۲ , ۴-Dichlorophenoxyacetic acid , ۴-Chloro-۲-methylphenoxyacetic acid , GC/MS