Magnetic mixed hemimicelles dispersive solid-phase extraction based on ionic liquid-coated attapulgite/polyaniline-polypyrrole/Fe 3 O 4 nanocomposites for determination of acaricides in fruit juice prior to high-performance liquid chromatography-diode array detection

Fe3O4@nitrogen-doped carbon core-double shell nanotubes as a novel and efficient nanosorbent for ultrasonic assisted dispersive magnetic solid phase extraction of heterocyclic pesticides from environmental soil and water samples

Fe3O4@nitrogen-doped carbon core-double shell nanotubes (Fe3O4@N-C C-DSNTs) were successfully synthesized and applied as a novel nanosorbent in ultrasonic assisted dispersive magnetic solid phase extraction (UA-DMSPE) of tribenuron-methyl, fenpyroximate, and iprodione. Subsequently, corona discharge ion mobility spectrometry (CD-IMS) was employed for the detection of the extracted analytes. Effective parameters on the extraction recovery percentage (ER%) were systematically investigated and optimized. Under optimal conditions, UA-DMSPE-CD-IMS demonstrated remarkable linearity in different ranges within 1.0 - 700 ng mL-1 with correlation coefficients exceeding 0.993, repeatability values below 6.9%, limits of detection ranging from 0.30 to 0.90 ng mL-1, high preconcentration factors (418 - 435), and ER% values (83 - 87%). The potential of the proposed method was further demonstrated by effectively determining the targeted pesticides in various environmental soil and water samples, exhibiting relative recoveries in the range 92.1 - 102%.

Hydrophilic-interaction-based magnetically assisted matrix solid-phase dispersion extraction of carbadox and olaquindox in feeds

BACKGROUND

Carbadox and olaquindox have been banned from feeds since 1998 by the EU because of their mutagenic, photoallergic, and carcinogenic effects. Unfortunately, owing to their outstanding effect, they are frequently abused or misused in animal husbandry. There is an urgent need to develop a sensitive and reliable method for monitoring these drugs in animal feeds.

RESULTS

This work reported a new method of hydrophilic-interaction-based magnetically assisted matrix solid-phase dispersion (MMSPD) extraction coupled with reversed-phase liquid chromatography-mass spectrometry for simultaneous determination of carbadox and olaquindox in animal feeds. 3-Trimethoxysilylpropyl methacrylate (γ-MAPS)-modified attapulgite (ATP) was crosslinked with γ-MAPS-modified iron(II,III) oxide (Fe₃ O₄ ), 1-vinyl-3-(butyl-4-sulfonate) imidazolium (VBSIm), acrylamide (AM), and N,N'-methylene-bis(acrylamide) (MBA) to synthesize ATP@Fe₃ O₄ @poly(VBSIm-AM-MBA) particles. The resultant particles were characterized by scanning electron microscopy, energy dispersive spectrometer, transmission electron microscopy, vibrating sample magnetometer, and Fourier transform infrared spectroscopy. Crosslinking of ATP into the magnetic particles has significantly increased the adsorption capacity of the particles. Under optimum conditions, the limits of detection (S/N = 3) were 0.3 μg kg^-1 and 0.9 μg kg^-1 for carbadox and olaquindox respectively. The intra-day and inter-day recoveries of the spiked targets in feed samples were in the range 83.5-98.3% with relative standard deviations of 1.0-8.3%.

CONCLUSION

With a simplified procedure and a low amount of sample, the proposed hydrophilic-interaction-based MMSPD method is not only useful for the determination of carbadox and olaquindox in feeds but also holds great promise for the analysis of other polar targets in solid or semisolid matrices. © 2021 Society of Chemical Industry.

Novel hydrophobic deep eutectic solvent for vortex-assisted liquid phase microextraction of common acaricides in fruit juice followed by HPLC-UV determination

In the present research, several novel and natural hydrophobic deep eutectic solvents (DESs) were prepared using methyltrioctylammonium chloride (MTOAC) as the hydrogen bond acceptor (HBA) and different types of straight chain alcohols as hydrogen bond donors (HBDs). One of the DESs composed of MTOAC and n-butanol was advantageously used to develop a vortex-assisted liquid phase microextraction (VALPME) method combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) for the determination of common acaricides in fruit juice samples. Several important parameters influencing extraction efficiency were investigated and optimized, including the type and volume of DES, sample solution pH, effect of salt addition and, extraction and vortex time. Under optimal experimental conditions, the method showed good linearity with the correlation coefficients (R 2) of 0.9986-0.9991 in the linear range of 2-300 μg L-1, low limits of detection of 0.5-1 μg L-1 and acceptable extraction recoveries in the range of 85-93%. The proposed method was successfully applied for the extraction and preconcentration of trace acaricides in real fruit juice samples, and the results demonstrated the potential of the synthesized DESs for the extraction and determination of contaminants in aqueous samples.

Simultaneous detection of multiple proteases using a non-array nanopore platform

Multiplexing methods which are capable of measurement of multiple analytes in a single assay are of great importance in many fields. The conventional strategy for simultaneous detection of multiple species is to construct a sensor array. Herein, we report an innovative multiplex multi-analyte detection platform in a non-array format for protease measurement. By monitoring protease degradation of a single peptide substrate containing two cleavage sites for a disintegrin and metalloproteinase 10 (ADAM10) and a disintegrin and metalloproteinase 10 (ADAM17) in a single nanopore, simultaneous detection and quantification of these two model proteases in mixture samples could satisfactorily be accomplished. Our developed multiplexing sensing platform has the potential to be coupled with the traditional sensor array to further improve the multiplexing capability of the sensor, which may find useful applications in clinical diagnosis and prognosis.

Polyethyleneimine-functionalized Fe3O4/attapulgite particles for hydrophilic interaction-based magnetic dispersive solid-phase extraction of fluoroquinolones in chicken muscle

Fluoroquinolone (FQ) residues in foods of animal origin may threaten public health but are challenging to determine because of their low contents and complex matrices. In this study, novel polyethyleneimine-functionalized Fe₃O₄/attapulgite magnetic particles were prepared by a simple co-mixing method and applied as hydrophilic sorbents for the magnetic dispersive solid-phase extraction (MSPE) of three FQs, i.e., ciprofloxacin, norfloxacin, and enrofloxacin, from chicken muscle samples. The preparation of the magnetic particles was of high reproducibility and the products could be reused many times with high adsorption capacity. The key experimental factors possibly influencing the extraction efficiencies, including sample solution, extraction time, sample loading volume, desorption solution, desorption time, and elution volume were investigated. Under optimum MSPE conditions, the analytes in chicken muscle samples were extracted and then determined by RPLC-MS/MS in MRM mode. Good linearity was obtained for the analytes with correlation coefficients ranged from 0.9975 to 0.9995. The limits of detection were in the range of 0.02-0.08 μg kg^-1, and the recoveries of the spiked FQs in chicken muscle samples ranged from 83.9 to 98.7% with relative standard deviations of 1.3-6.8% (n = 3). Compared with the traditional MSPE methods based on hydrophobic mechanism, this hydrophilic interaction-based method significantly simplifies the sample pretreatment procedure and improves repeatability. This method is promising for accurate monitoring of FQs in foods of animal origin.

[Research progress in application of immobilized ionic liquid materials to separation by solid-phase extraction]

Ionic liquids are low-temperature molten salts with almost no vapor pressure, and they are composed of organic cations and inorganic anions. Ionic liquids are characterized by the properties of good chemical stability, high solubility, designable structure, high conductivity and so on. The physicochemical properties of an ionic liquid depend on the nature and size of the cation and anion, which confer unique characteristics; hence, these reagents are also termed "designed extractants." As a new class of green solvents, ionic liquids are potential replacements to traditional volatile organic solvents used for extraction; for this reason, ionic liquids have attracted the attention of scientists. Research on the methods of preparation and applications of ionic liquids is being diversified, and they are extensively used in catalytic chemistry, photoelectron chemistry, materials chemistry, analytical chemistry, etc. By functional guiding design, the structures of ionic liquids, especially the imidazole ring cations, can be easily grafted with active groups such as hydroxyl, amino, carboxyl, and cyano groups, so that interactions between the ionic liquids and target molecules can be promoted via the formation of π-π bonds, hydrogen bonds, ionic bonds, and van der Waals forces. In addition, ionic liquids can be readily immobilized on solid carriers by physical or chemical means in order to obtain a new solid material with ionic liquids embedded internally or decorated on the surface. Furthermore, ionic liquids could be converted into ionic liquid-immobilized composite materials by impregnation, grafting, etc. The resulting composites not only suffer minimal loss of ionic liquids but also retain the typical characteristics of the ionic liquids and solid materials, thus showing improved mass transfer performance and better adsorption performance. Immobilized materials are characterized by high enrichment efficiency, high adsorption capacity, good stability, and strong extraction selectivity, as well as the presence of numerous recognition sites and high utilization rate of ionic liquids. In recent years, they have been widely used as solid-phase extraction adsorption materials for the separation of small organic molecules. This review introduces common immobilization methods and the characteristics of ionic liquid-immobilized materials, as well as their application in solid-phase extraction. In this paper, methods for the immobilization of ionic liquids with solid carriers such as silica gel, molecular sieves, molecularly imprinted polymers, graphene oxide, and magnetic nanomaterials are summarized, and the application of ionic liquid-immobilized materials in solid-phase extraction is reviewed. The target substances include alkaloids, flavonoids, polyphenols, and other natural active components as well as common drug molecules, organic pesticides, and other organic small molecular compounds. The properties, applications, and separation mechanisms of ionic liquids immobilized with various carriers are systematically introduced. Literature survey shows that the distribution of the binding active sites of ionic liquid-immobilized materials to the target molecules is more uniform, which increases the adsorption capacity of the materials. The adsorption efficiency of ionic liquid-immobilized materials is related to the type of ionic liquid, amount of adsorption material, concentration of the sample solution, adsorption temperature, solution pH, flow rate of the eluent, and type and amount of the eluting solvent. The existing disadvantages of ionic liquids, such as simple structures, insufficient basic theoretical research, and unsatisfactory extraction degree in complex matrixes would also be discussed. The corresponding solutions would be presented with the aim of providing guidance for the application of ionic liquid-immobilized materials in the separation and analysis of targets in complex matrices, thus paving the way for a new direction in the field of extraction and separation.

Enhanced extraction of organophosphorus pesticides from fruit juices using magnetic effervescent tablets composed of the NiFe2O4@SiO2@PANI-IL nanocomposites

The reported ionic liquid (IL)-based magnetic effervescent tablets are a result of direct addition of ILs and magnetic nanoparticles (MNPs). In effervescent reaction-enhanced microextraction procedures, the dissociation between ILs and MNPs easily leads to loss of ILs due to aqueous solubility, thereby decreasing the extraction efficiency. Herein, we attached a hydrophilic IL ([BMIM]Br) onto the surface of NiFe₂O₄@SiO₂@polyaniline (NiFe₂O₄@SiO₂@PANI-IL) to prepare novel core–shell-like multi-layer nanocomposites. Magnetic effervescent tablets were composed of Na₂CO₃ as an alkaline source, tartaric acid as an acidic source and as-synthesized nanocomposites as an extractant. The nanocomposites were used in an effervescent reaction-enhanced magnetic solid-phase extraction (ERMSE) for the extraction of four organophosphorus pesticides (OPPs) in fruit juices prior to HPLC-DAD detection. Under optimized conditions, this method provided low limits of detection (0.06–0.17 μg L⁻¹), high recoveries (80.6–97.3%) and excellent precision (1.1–5.2%) for OPP quantification in five fruit juices. Notably, the three-layer core–shell nanocomposites were efficiently recycled for at least eight extraction cycles with a recovery loss of <10%. The novelty of this study lies in: (1) for the first time, the ILs-based hybrid magnetic nanocomposites were prepared with appropriate pore size/volume and more active sites for OPPs; (2) the combination of the nanocomposites with effervescent tablets realizes rapid dispersion of CO₂ bubbles, and convenient magnetic separation/collection into one synchronous step; and (3) due to there being no requirement of electrical power, it is feasible for use in field conditions. Thus, the ERMSE method has excellent potential for conventional monitoring of trace-level OPPs in complex fruit juice matrices.

The reported ionic liquid (IL)-based magnetic effervescent tablets are a result of direct addition of ILs and magnetic nanoparticles (MNPs).

Sustainable polypyrrole-based magnetic-microextraction of phthalates from jellies and apple-based beverages prior to tandem mass spectrometry analysis

Synthesised polypyrrole-coated Fe₃O₄ magnetic nanoparticles have been successfully characterised and applied as sorbent for the magnetic-micro-dispersive solid-phase extraction of eleven phthalic acid esters from jelly and apple-based beverage matrices widely consumed by the population and, especially, by children. Sorbent was synthesised through chemical coprecipitation and subsequently characterised by different techniques. The influence of several parameters on the extraction efficiency was exhaustively evaluated using a step-by-step strategy. The separation and quantification of the selected phthalates were performed by ultra-high performance liquid chromatography coupled to tandem mass spectrometry. The validation of the methodology was carried out for jellies and apple-based beverages, employing dihexyl phthalate-3,4,5,6-d₄ as the surrogate standard. Relative recovery values were in the range 70-114% for both matrices and relative standard deviations below 20% were obtained. The limits of quantification of the method were found in the range 0.147-0.416 µg/L. Feasibility of the developed methodology was proved by the analysis of commercialised jelly and apple-based beverage products.

Recent Applications of Magnetic Nanoparticles in Food Analysis

Nanotechnology has become a topic of interest due to the outstanding advantages that the use of nanomaterials offers in many fields. Among them, magnetic nanoparticles (m-NPs) have been one of the most widely applied in recent years. In addition to the unique features of nanomaterials in general, which exclusively appear at nanoscale, these present magnetic or paramagnetic properties that result of great interest in many applications. In particular, in the area of food analysis, the use of these nanomaterials has undergone a considerable increase since they can be easily separated from the matrix in sorbent-based extractions, providing a considerable simplification of the procedures. This allows reducing cost and giving fast responses, which is essential in the food trade to guarantee consumer safety. These materials can also be easily tunable, providing higher selectivity. Moreover, their particular electrical, thermal and optical characteristics allow enhancing sensor signals, increasing the sensitivity of the approaches based on this type of device. The aim of this review article is to summarise the most remarkable applications of m-NPs in food analysis in the last five years (2016–2020) showing a general view of the use of such materials in the field.

Chemical Fingerprint Analysis and Simultaneous Determination of Nucleosides and Amino Acids in Kang Fu Xin Liquid by High Performance Liquid Chromatography with Diode Array Detector

Background and Objective:

Kang Fu Xin liquid (KFX) is an official preparation made from the ethanol extract product from P. Americana. The present quality control method cannot control the quality of the preparation well. The aim of the present study is to establish a convenient HPLC method for multicomponents determination combined with fingerprint analysis for quality control of KFX.

Methods:

An HPLC-DAD method with gradient elution and detective wavelength switching program was developed to establish HPLC fingerprints of KFX, and 38 batches of KFX were compared and evaluated by similarity analysis (SA), hierarchical clustering analysis (HCA), and principal component analysis (PCA). Meanwhile, six nucleosides and three amino acids, including uracil, hypoxanthine, uric acid, adenosine, xanthine, inosine, tyrosine, phenylalanine and tryptophan in KFX were determined based on the HPLC fingerprints.

Results:

An HPLC method assisted with gradient elution and wavelength switching program was established and validated for multicomponents determination combined with fingerprint analysis of KFX. The results demonstrated that the similarity values of the KFX samples were more than 0.845. PCA indicated that peaks 4 (hypoxanthine), 7 (xanthine), 9 (tyrosine), 11, 13 and 17 might be the characteristic contributed components. The nine constituents in KFX, uracil, hypoxanthine, uric acid, adenosine, xanthine, inosine, tyrosine, phenylalanine and tryptophan, showed good regression (R2 > 0.9997) within test ranges and the recoveries of the method for all analytes were in the range from 96.74 to 104.24%. The limits of detections and quantifications for nine constituents in DAD were less than 0.22 and 0.43 μg•mL-1, respectively.

Conclusion:

The qualitative analysis of chemical fingerprints and the quantitative analysis of multiple indicators provide a powerful and rational way to control the KFX quality for pharmaceutical companies.

Role of Ionic Liquids in Composites in Analytical Sample Preparation

Ionic liquids (ILs) are a group of non-conventional salts with melting points below 100 °C. Apart from their negligible vapor pressure at room temperature, high thermal stability, and impressive solvation properties, ILs are characterized by their tunability. Given such nearly infinite combinations of cations and anions, and the easy modification of their structures, ILs with specific properties can be synthesized. These characteristics have attracted attention regarding their use as extraction phases in analytical sample preparation methods, particularly in liquid-phase extraction methods. Given the liquid nature of most common ILs, their incorporation in analytical sample preparation methods using solid sorbents requires the preparation of solid derivatives, such as polymeric ILs, or the combination of ILs with other materials to prepare solid IL-based composites. In this sense, many solid composites based on ILs have been prepared with improved features, including magnetic particles, carbonaceous materials, polymers, silica materials, and metal-organic frameworks, as additional materials forming the composites. This review aims to give an overview on the preparation and applications of IL-based composites in analytical sample preparation in the period 2017–2020, paying attention to the role of the IL material in those composites to understand the effect of the individual components in the sorbent.

Humic acid functionalized hyperbranched polytriazine based dispersive solid-phase extraction for acaricides determination in tea matrix

Hyperbranched polytriazine functionalized with humic acid was prepared and developed as new sorbents for dispersive solid-phase extraction of three acaricides (clofentezine, fenpyroximate, and pyridaben) in tea samples combined with high-performance liquid chromatography detection. The sorbents were characterized by scanning electron microscopy, energy dispersive spectroscopy, Zeta-potential, and Fourier transform infrared spectroscopy. The extraction parameters (extraction time, ionic strength, desorption conditions) were optimized. The adsorption mechanism was evaluated utilizing Fourier transform infrared spectra. Under optimum conditions, satisfactory analytical performances were achieved, which included high precision (1.33-9.62%), low limits of detection (0.19-3.54 µg/L), and wide linear range (2.5-500 µg/L) for the analysis of the acaricides. Moreover, the proposed method proved highly effective for the determination of acaricides in tea samples, with the relative recoveries in the range of 65.20-108.13% and relative standard deviations < 9.87%. The method has great application potential for the detection of acaricides in tea samples.

Synthesis of amino-functionalized bentonite/CoFe2O4@MnO2 magnetic recoverable nanoparticles for aqueous Cd2+ removal

Magnetic nano-composite materials have been attracting considerable attention due to their unique properties and versatile applications. In this study, a novel magnetic amino-functionalized conjugate adsorbent, named as bentonite/CoFe₂O₄@MnO₂-NH₂ (BCFMNs), was synthesized by combining APTES and MnO₂ with magnetic bentonite. XRD, FT-IR, SEM, EDS, TEM, and VSM techniques were used to characterize its structure and magnetic properties. Results were in indicative of productive synthesis, well-defined architecture and satisfactory magnetism. BET examinations illustrated 84.97m²/g of specific surface area, 0.15cm³/g of pore volume and 7.02nm average pore size. The effect parameters such as adsorbent dosage, contact time, initial concentration and ion selectivity and recycling were evaluated and optimized systematically. Also, the metal concentrations were measured by ICP-MS spectrometer. The feasibility of the BCFMNs for removal of Cd²⁺ from aqueous solution was also evaluated by adsorption experiments with the maximal adsorption efficiency for Cd²⁺ up to 98.88%. Cd²⁺ adsorption could be interpreted by the Langmuir adsorption isotherm and the maximum adsorption capacity was 115.79mg/g. The results revealed that the adsorbent still had higher selectivity of Cd²⁺ removal even in the presence of high concentration coexisting cations. The as-prepared magnetic conjugate adsorbent could be recycled by taking advantage of its magnetic properties. The distinctive structure of BCFMNs and its excellent adsorption performance of cadmium reflects its prospective application in water treatment.

Evaluation of Pyridaben Residues on Fruit Surfaces and Their Stability by a Novel On-Line Dual-Frequency Ultrasonic Device and Chemiluminescence Detection

In this paper, we first report the development of a highly sensitive and economical method for accurate analysis of pyridaben residues on fruits based on dual-frequency ultrasonic treatment (DFUT) and flow injection chemiluminescence (CL) detection. The DFUT device is made by integrating an ultrasonic bath with an ultrasonic probe. Two quartz glass coils (QGC) with different structures have been designed and applied to evaluate the function of DFUT in the detection process. Recorded data showed that DFUT is an effective method for improving the pyridaben CL signal. The signal of pyridaben in response to DFUT is 2.0-3.3 times stronger than the response to only the ultrasonic probe at 20 kHz or the ultrasonic bath at 40 kHz. In addition, the response obtained from the concentric circle QGC is 2.1 times stronger than the response to the spiral tube QGC. Under the optimized condition, the proposed method has advantages, such as a wide linear range (0.8-100.0 μg L^-1), a high sensitivity (limit of detection of 0.085 μg L^-1), and good stability (RSDs ≤ 4.7% in the linear range) for pyridaben determination. We apply this method to monitor the residue pyridaben on some fruits. The data show that the maximum amounts of the residue on fruit surfaces after soaking in water (50 mg L^-1, 5 min) are 0.583 mg kg^-1 (apple), 0.794 mg kg^-1 (orange), and 0.351 mg kg^-1 (pear). However, the concentration of pyridaben in the presence of sunlight decreases rapidly, showing its poor light stability.