Magnetic solid-phase extraction based on zirconium-based metal-organic frameworks for simultaneous enantiomeric determination of eight chiral pesticides in water and fruit juices.

A novel multi-residue method, magnetic solid-phase extraction combined with LC-MS/MS, was proposed for simultaneous enantiomeric determination of eight chiral pesticides in water and fruit juices. Fe3O4@C@UiO-66 was firstly used to extract and enrich pesticides, showing excellent adsorption capacity, which was proved by adsorption kinetic and thermodynamic experiments. Multiple extraction parameters were optimized by Plackett-Burman and Box-Behnken design. Under optimized conditions, good linearity (1.0-200 ng L-1, R2 ≥ 0.9953) for all analytes, detection limits (0.10 to 0.35 ng L-1), quantitation limits (0.35 to 1.00 ng L-1), recoveries (83.68-95.99%), and precision (intra-day RSD ≤ 7.06%, inter-day RSD ≤ 9.40%) were obtained, meeting the requirements of pesticides residues analysis. It is worth mentioning that eight chiral pesticides can be separated quickly within 19 min. The above results indicate that the proposed method with satisfactory sensitivity and accuracy has the potential for routine analysis of chiral pesticide residues in aqueous samples.

A new composite based on graphene oxide-poly 3-aminophenol for solid-phase microextraction of four triazole fungicides in water and fruit juices prior to high-performance liquid chromatography analysis.

An environmentally friendly method which is based on preparation and use of a new composite consisting of poly 3-aminophenol and graphene oxide for solid-phase microextraction of triazole fungicides from natural water and juices is introduced. The composite was synthesized by in-situ polymerization of 3-aminophenol and graphene oxide in weak alkaline media. By using the obtained results from the characterization, a suitable mechanism for polymerization and a proper structure for the polymer were proposed. Under optimal conditions, there are linear relationships between concentration of triazoles and their HPLC peak areas in the range of 0.5-100 µg L-1. The recovery percentages, pre-concentration factors and LOQ for all triazoles were 95.2-98.0%, about 200 and 0.2-0.4 µg L-1, respectively. The offered method was applied for extraction and determination of triazoles from natural water, some juices and it represents a promising alternative method for analysis of triazoles.