Application of additional factors supporting the microextraction process

A study on the enrichment mechanism of three nitrophenol isomers in environmental water samples by charge transfer supramolecular-mediated hollow fiber liquid-phase microextraction

To explore the mechanism of extraction and enrichment of three nitrophenol isomers by charge-transfer supramolecular synergistic three-phase microextraction system, a charge transfer supramolecular-mediated hollow fiber liquid-phase microextraction (CTSM-HF-LPME) combined with high-performance liquid chromatography-ultraviolet detector (HPLC-UV) method was established for the determination of real environmental water samples. In this study, the three nitrophenols (NPs) formed charge-transfer supramolecules with electron-rich hollow fibers, which promoted the transport of NPs in the three-phase extraction system and greatly increased the EFs of NPs. The relationships between the EFs of NPs and their solubility, pK_a, apparent partition coefficient, equilibrium constant, and structural property parameters were investigated and discussed. At the same time, most of factors affecting the EFs of NPs were investigated and optimized, such as the type of extraction solvent, pH value of sample phase and acceptor phase, extraction time, and stirring speed. Under optimal conditions, the EFs of o-nitrophenol, m-nitrophenol, and p-nitrophenol were 163, 145, and 87, respectively. With good linearity in the range of 5 × 10^-7 ~ 1 µg/mL, and the limit of detection of 0.1 pg/mL, the relative standard deviations of the method precision were lower than 7.4%, and the average recoveries were between 98.6 and 106.4%. This method had good selectivity and sensitivity, satisfactory precision, and accuracy and had been successfully applied to the trace detection of real water samples.

Application of phosphonium deep eutectic solvents as extractants in ultrasound-assisted dispersive liquid-liquid microextraction for preconcentration of trace amounts of herbicides in drainage ditches waters

In this study, an efficient preconcentration method was presented that is based on dispersive liquid-liquid microextraction taking the advantage of newly synthesized phosphonium deep eutectic solvents used as extractants and ultrasound probe as a dispersing agent. The extracts obtained were analyzed by high-performance liquid chromatography. To optimize the five most important factors for the microextraction procedure a central composite design plan was used. Under optimal conditions (140 μl of extractant, 60 mg of NaCl, pH = 2.0, 120 s of extraction time with ultrasound probe as the dispersing agent, 16 min of centrifugation for phase separation), the proposed method allowed to achieve good precision with RSD between 3.2% and 9.7% at 1.0, 5.0 and 40.0 ng ml levels. The preconcentration factors were equal to 42, 39, and 41, and the limits of detection 0.128, 0.103, and 0.135 ng/ml for dicamba, 2-methyl-4-chlorophenoxyacetic acid, and 2-methyl-4-chlorophenoxypropionic acid, respectively. The proposed method was successfully applied for the determination of chlorophenoxy acid herbicides in water samples from drainage ditches with a good recovery in the range of 70%-93%.

A review of flaxseed lignan and the extraction and refinement of secoisolariciresinol diglucoside

Lignan is a class of diphenolic compounds that arise from the condensation of two phenylpropanoid moieties. Oilseed and cereal crops (e.g., flaxseed, sesame seed, wheat, barley, oats, rye, etc.) are major sources of plant lignan. Methods for commercial isolation of the lignan secoisolariciresinol diglucoside (SDG) are not well reported, as most publications describing the detection, extraction, and enrichment of SDG use methods that have not been optimized for commercial scale lignan recovery. Simply scaling up laboratory methods would require expensive infrastructure to achieve a marketable yield and reproducible product quality. Therefore, establishing standard protocols to produce SDG and its derivatives on an industrial scale is critical to decrease lignan cost and increase market opportunities. This review summarizes the human health benefits of flaxseed lignan consumption, lignan physicochemical properties, and mammalian lignan metabolism, and describes methods for detecting, extracting, and enriching flaxseed lignan. Refining and optimization of these methods could lead to the development of inexpensive lignan sources for application as an ingredient in medicines, dietary supplements, and other healthy ingredients.

Inhalation bioaccessibility estimation of polycyclic aromatic hydrocarbons from atmospheric particulate matter (PM10): Influence of PM10 composition and health risk assessment

Polycyclic aromatic hydrocarbons (PAHs) inhalation bioaccessibility was assessed in 65 atmospheric particulate matter samples (PM₁₀) collected at an Atlantic coastal European urban site. The proposed method consists on a physiologically based extraction (PBET) by using Gamble's solution followed by a vortex assisted liquid-liquid micro-extraction (VALLME) and quantification by high performance liquid chromatography with fluorescence detection (HPLC-FLD). The use of a micro-extraction technique combined with FLD detection, provides a simple, fast, sensitive, accurate and low-cost methodology to PAHs quantification in bioaccessible fractions. Accuracy of the bioaccessibility study was assessed by means of a mass balance approaches using a PM₁₀ filter and a certified reference material (ERM-CZ100). High-moderate inhalation bioaccessibilities were found for phenanthrene (Phe), fluoranthene (Ft) and pyrene (Pyr) (average ratios in the 52-65% range); while dibenz (a,h)anthracene (DBahA), indeno (1,2,3-cd)pyrene (IP) and benzo (g,h,i)perylene (BghiP) were observed to be less bioaccessibles (average ratios in the 11-14% range). Relationship between PM₁₀ composition (major ions, trace metals, equivalent black carbon (eBC) and UV-absorbing particulate matter (UVPM)) and PAHs bioaccessibility ratios was also assessed. Principal Component Analysis (PCA) showed that PAHs bioaccessibility percentage is dependent on anthropogenic (eBC, UVPM and Sb concentrations) and marine sources of PM₁₀. Predicted PAHs bioaccessibilities after applying a multiple linear regression model based on marine and anthropogenic source of PM₁₀ could also be established. Health risk assessment of target PM₁₀-associated PAHs via inhalation was assessed considering bioaccessibility concentrations by using hazard index (HI) and BaP equivalent concentration (BaP_eq) approaches, suggesting no carcinogenic risk in the area during the sampling campaign.

Miniaturized analytical methods for determination of environmental contaminants of emerging concern - A review

The determination of contaminants of emerging concern (CECs) in environmental samples has become a challenging and critical issue. The present work focuses on miniaturized analytical strategies reported in the literature for the determination of CECs. The first part of the review provides brief overview of CECs whose monitoring in environmental samples is of particular significance, namely personal care products, pharmaceuticals, endocrine disruptors, UV-filters, newly registered pesticides, illicit drugs, disinfection by-products, surfactants, high technology rare earth elements, and engineered nanomaterials. Besides, an overview of downsized sample preparation approaches reported in the literature for the determination of CECs in environmental samples is provided. Particularly, analytical methodologies involving microextraction approaches used for the enrichment of CECs are discussed. Both solid phase- and liquid phase-based microextraction techniques are highlighted devoting special attention to recently reported approaches. Special emphasis is placed on newly developed materials used for extraction purposes in microextraction techniques. In addition, recent contributions involving miniaturized analytical flow techniques for the determination of CECs are discussed. Besides, the strengths, weaknesses, opportunities and threats of point of need and portable devices have been identified and critically compared with chromatographic methods coupled to mass chromatography. Finally, challenging aspects regarding miniaturized analytical methods for determination of CECs are critically discussed.

Polyoxomolybdate368 /polyaniline nanocomposite as a novel fiber for solid-phase microextraction of antidepressant drugs in biological samples

A novel solid-phase microextraction fiber was synthesized by coating a stainless steel wire with polyoxomolybdate₃₆₈ /polyaniline as a sorbent aimed at extraction of amitriptyline, nortriptyline, and doxepin as antidepressant drugs from urine and blood samples. The polyoxomolybdate₃₆₈ /polyaniline composite coating was applied using electropolymerization process under constant potential. This composition leads to enhanced extraction efficiency of the fiber. Scanning electron microscopy images show that huge three-dimensional structures of polyoxomolybdate₃₆₈ in composite induced more non-smooth and porous fiber. In order to optimize of the extraction process, a series of variables including concentration of the composite materials, coating thickness, pH, extraction time, salt addition, and stirring rate was investigated and optimum conditions were determined. Analysis of surface morphology and chemical composition was performed. High-performance liquid chromatography was used for separation and evaluation of mentioned antidepressant drugs from the matrixes. The experiments indicated a detection limits of <0.2 ng/L and a linear dynamic range of 0.3-100 ng/L (R²  > 0.994). The relative recovery values were found to be in the range of 92-98%. It was concluded that the purposed fiber is highly efficient in analyzing traces of antidepressant drugs in urine and blood.

Recent Trends in the Development of Green Microextraction Techniques for the Determination of Hazardous Organic Compounds in Wine

Background:

The sample preparation is the most crucial step in the analytical method development. Taking this into account, it is easily understood why the domain of sample preparation prior to detection is rapidly developing. Following the modern trends towards the automation, miniaturization, simplification and minimization of organic solvents and sample volumes, green microextraction techniques witness rapid growth in the field of food quality and safety. In a globalized market, it is essential to face the consumers need and develop analytical methods that guarantee the quality of food products and beverages. The strive for the accurate determination of organic hazards in a famous and appreciated alcoholic beverage like wine has necessitated the development of microextraction techniques.

Objective:

The objective of this review is to summarize all the recent microextraction methodologies, including solid phase extraction (SPE), solid phase microextraction (SPME), liquid-phase microextraction (LPME), dispersive liquid-liquid microextraction (DLLME), stir bar sorptive extraction (SBSE), matrix solid-phase dispersion (MSPD), single-drop microextraction (SDME) and dispersive solid phase extraction (DSPE) that were developed for the determination of hazardous organic compounds (pesticides, mycotoxins, colorants, biogenic amines, off-flavors) in wine. The analytical performance of the techniques is evaluated and their advantages and limitations are discussed.

Conclusion:

An extensive investigation of these techniques remains vital through the development of novel strategies and the implication of new materials that could upgrade the selectivity for the extraction of target analytes.

In-line carbon nanofiber reinforced hollow fiber-mediated liquid phase microextraction using a 3D printed extraction platform as a front end to liquid chromatography for automatic sample preparation and analysis: A proof of concept study

A novel concept for automation of nanostructured hollow-fiber supported microextraction, combining the principles of liquid-phase microextraction (LPME) and sorbent microextraction synergically, using mesofluidic platforms is proposed herein for the first time, and demonstrated with the determination of acidic drugs (namely, ketoprofen, ibuprofen, diclofenac and naproxen) in urine as a proof-of-concept applicability. Dispersed carbon nanofibers (CNF) are immobilized in the pores of a single-stranded polypropylene hollow fiber (CNF@HF) membrane, which is thereafter accommodated in a stereolithographic 3D-printed extraction chamber without glued components for ease of assembly. The analytical method involves continuous-flow extraction of the acidic drugs from a flowing stream donor (pH 1.7) into an alkaline stagnant acceptor (20 mmol L^-1 NaOH) containing 10% MeOH (v/v) across a dihexyl ether impregnated CNF@HF membrane. The flow setup features entire automation of the microextraction process including regeneration of the organic film and on-line injection of the analyte-laden acceptor phase after downstream neutralization into a liquid chromatograph (LC) for reversed-phase core-shell column-based separation. Using a 12-cm long CNF@HF and a sample volume of 6.4 mL, linear dynamic ranges of ketoprofen, naproxen, diclofenac and ibuprofen, taken as models of non-steroidal anti-inflammatory drugs, spanned from ca. 5-15 µg L^-1 to 500 µg L^-1 with enhancement factors of 43-97 (against a direct injection of 10 µL standards into LC), and limits of detection from 1.6 to 4.3 µg L^-1. Relative recoveries in real urine samples ranged from 97% to 105%, thus demonstrating the reliability of the automatic CNF@HF-LPME method for in-line matrix clean-up and determination of drugs in urine at therapeutically relevant concentrations.

A lighter-than-water deep eutectic-solvent-based dispersive liquid-phase microextraction method in a U-shaped homemade device

A new microextraction method, termed glass-filter-based dispersive liquid-phase microextraction using a lighter-than-water deep eutectic solvent, was developed for the extraction and preconcentration of different classes of pesticides from fruit juice and vegetable samples.