Ionic-liquid-based dispersive liquid-liquid microextraction for high-throughput multiple food contaminant screening.

This paper describes an innovation of dispersive liquid-liquid microextraction enabling multiple-component analysis of eight high-priority food contaminants in two chemically distinctive families: Sudan dyes and phthalate plasticizers. To provide convenient sample handling for solid and solid-containing matrices, a modified dispersive liquid-liquid microextraction procedure used an extractant precoated frit to perform simultaneous filtration, solvent mixing, and phase dispersion in one simple step. A binary ionic liquid extractant system was carefully tuned to deliver high quality analysis based only on affordable LC with diode array detector instrumentation. The method is comprehensively validated for robust quantification with good precision (6.9-9.8% RSD) in a linear 2-1000 µg/L range. Having accomplished enrichment factors up to 451, the treatment enables sensitive detection at 0.09-1.01 µg/L levels. Analysis of six high-risk solid condiments and sauces further verified its practical applicability within a 70-120% recovery range. Compared to other approaches, the current dispersive liquid-liquid microextraction treatment offers major advantages in terms of minimal solvent (1.5 mL) and sample (0.1 g) consumption, ultra-high analytical throughput (6 min), and the ability to handle complex solid matrices. The idea of performing simultaneous analysis for multiple contaminants presented here fosters a more effective mode of operation in food control routines.

Highly sensitive and selective organophosphate screening in twelve commodities of fruits, vegetables and herbal medicines by dispersive liquid-liquid microextraction.

The article describes a simple sample pretreatment procedure for the analysis of ten organophosphorus pesticides using dispersive liquid-liquid microextraction (DLLME) followed by gas chromatography-mass spectrometry (GC-MS) in three distinctively different types of matrices: fresh fruits, fresh vegetables and dried herbs. The method was carefully developed, focusing on the chemistry of various dispersive solvents, to achieve simultaneous, comprehensive extraction and preconcentration in a great span of selected matrices. According to matrix-matched validation study, the set of optimized DLLME conditions has been proven robust to determine target OPPs within a wide linear range from 0.1 to 1000 µg L(-1). With limited usage of organic extractants, remarkable enrichment factors up to 100-fold were obtained, enabling ultra-trace pesticide quantification down to sub-ppt levels at 0.12-4.92 ng kg(-1). Practical application of the method was illustrated by quantitative recovery (70-119%) and good precision (2.6-10% R.S.D.) in a representative range of three fruits and four vegetable commodities featured by the CODEX Alimentarius classification as well as their unique matrix compositions. A careful selection of dried herbs was further classified based on their morphological structures to validate analytical ruggedness of the method. Compared with existing methods for food analysis vis-à-vis OPPs, the present method is superior in terms of high sample throughput, minimal solvent consumption, and small sample size requirement. An additional, significant aspect of this universal DLLME method is that it models sample pretreatment methods with wide coverage of analytical matrices that are more effective, more comprehensive, and more flexible than those currently being used.

Selective recognition of arsenic by tailoring ion-imprinted polymer for ICP-MS quantification.

A novel arsenic-ion imprinted polymer (As-IIP) was firstly synthesized for the separation and recovery of trace elemental As from environmental water samples. Polymers prepared from bifunctional monomers with intrinsic metal-binding capability are a platform for tailoring ion-selectivity via imprinting moiety-template interaction, without complex formation and ligand immobilization. In the present study, As-IIPs based on 1-vinylimidazole, 4-vinylpyridine and styrene were designed to investigate the imprinting mechanism in relation to their structural and functional properties. In terms of selectivity as well as imprinting effects compared with the non-imprinted polymer (NIP), 1-vinylimidazole-based As-IIP exhibited superior analyte recognition for As ion among 23 competing elements, with a 25-fold enhancement in the practical dynamic and static adsorption capacity range (0.048-4.925 µmol g(-1)). The robust As-IIP sorbent features good reusability up to 20 cycles and a wide working pH 5-7 for a firstly reported solid-phase extraction (SPE) application. As a result of selective sample clean-up, As-IIP-SPE offered limits of detection (LOD) and quantification (LOQ) down to 0.025 and 0.083 µmol L(-1), respectively, for environmental sample analysis using inductively coupled plasma-mass spectrometry.