Halloysite nanotubes-titanium dioxide as a solid-phase microextraction coating combined with negative corona discharge-ion mobility spectrometry for the determination of parathion

A novel halloysite nanotubes-based hybrid monolith for in-tube solid-phase microextraction of polar cationic pesticides

The accurate determination of polar cationic pesticides in food poses a challenge due to their high polarity and trace levels in complex matrices. This study hypothesized that the use of halloysite nanotubes (HNTs) can significantly enhance the extraction efficiency and sensitivity of these analytes because of their rich hydroxyl groups and cation exchange sites. Therefore, we chemically incorporated HNTs with organic polymer monoliths for in-tube solid-phase microextraction (SPME). This novel hybrid monolith extended service life, improved adsorption capacity, and exhibited excellent extraction performance for polar cationic pesticides. Based on these advancements, a robust and sensitive in-tube SPME-HILIC-MS/MS method was constructed to determine trace levels of polar cationic pesticides in complex food matrices. The method achieved limits of detection of 1.9, 2.1, and 0.1 μg/kg for maleic hydrazide, amitrole, and cyromazine, respectively. The spiked recoveries in five food samples ranged from 80.2 to 100.8%, with relative standard deviations below 10.7%.

PEG-modified halloysite as a hydrophilic interaction and cation exchange mixed-mode sorbent for solid-phase extraction of biogenic amines in fish samples

A novel type of PEG-modified halloysite was prepared and used as a hydrophilic interaction and cation exchange mixed-mode sorbent for solid-phase extraction of biogenic amines in fish samples. The eluates were analyzed by high-performance liquid chromatography-ultraviolet detection after the derivatization with benzoyl chloride. The developed sorbent was characterized by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, zeta potential analyzer, and thermo-gravimetric analysis. After the optimization of various parameters influencing the extraction efficiency, the PEG-modified halloysite-based SPE method was evaluated. The adsorption capacities of putrescine, spermine, phenethylamine, and histamine were as high as 9.3, 8.5, 5.7, and 5.6 mg g-1, respectively. Satisfactory reproducibility of sorbent preparation was obtained with within-batch and batch-to-batch relative standard deviations (RSDs) lower than 3.9% and 8.6%, respectively. The biogenic amine spiking recoveries in fish samples ranged from 84.3 to 105.5% with good RSDs lower than 7.8%. Intra-day and inter-day precision, expressed as RSDs, were better than 8.8%. The limits of detection of histamine, putrescine, phenethylamine, and spermine were 9.4, 1.9, 0.5, and 0.9 μg L-1, respectively. This work provides a new hydrophilic interaction and cation exchange mixed-mode sorbent and is successfully applied to the extraction of trace biogenic amines from fish samples.

Centrifuge-free dispersive liquid-liquid microextraction coupled with thin-film microextraction for the preconcentration of molinate in real samples by ion mobility spectrometry

A tandem microextraction method, centrifuge free dispersive liquid-liquid microextraction and thin-film microextraction (DLLME-TFME), was used for analyzing molinate in environmental samples by ion mobility spectrometry (IMS). Considering the IMS as a competitive detection system, coupling these two popular sample preparation methods reduces the effect of solvent interference and improves the sensitivity of the technique. Trichloromethane and methanol were used as the extraction, and dispersive solvents for the DLLME method and electrospun polyacrylonitrile/copper-benzene-1,4-dicarboxylic acid fibers were used as a sorbent in the TFME method. Some effective experimental variables influencing the extraction efficiency of an analyte such as type and volume of dispersive and extraction solvents, solution pH, ionic strength, sonication time, and extraction time were studied. The linear dynamic range of 0.5-50 μg L^-1 and the limit of detection of 0.1 μg L^-1 were obtained under optimized conditions. The relative standard deviations for intra-and inter-day analysis were calculated less than 10%. The present method was used for the determination of molinate in different real samples such as agricultural wastewater, well water, river water, and apple, and the recovery was obtained between 82% and 113%, for the spiked samples.

Food safety and quality assessment: comprehensive review and recent trends in the applications of ion mobility spectrometry (IMS)

Ion mobility spectrometry (IMS) is an analytical separation and diagnostic technique that is simple and sensitive and a rapid response and low-priced technique for detecting trace levels of chemical compounds in different matrices. Chemical agents and environmental contaminants are successfully detected by IMS and have been recently considered to employ in food safety. In addition, IMS uses stand-alone or coupled analytical diagnostic tools with chromatographic and spectroscopic methods. Scientific publications show that IMS has been applied 21% in the pharmaceutical industry, 9% in environmental studies and 13% in quality control and food safety. Nevertheless, applications of IMS in food safety and quality analysis have not been adequately explored. This review presents the IMS-related analysis and focuses on the application of IMS in food safety and quality. This review presents the important topics including detection of traces of chemicals, rate of food spoilage and freshness, food adulteration and authenticity as well as natural toxins, pesticides, herbicides, fungicides, veterinary, and growth promoter drug residues. Further, persistent organic pollutants (POPs), acrylamide, polycyclic aromatic hydrocarbon (PAH), biogenic amines, nitrosamine, furfural, phenolic compounds, heavy metals, food packaging materials, melamine, and food additives were also examined for the first time. Therefore, it is logical to predict that the application of the IMS technique in food safety, food quality, and contaminant analysis will be impressively increased in the future. HighlightsCurrent status of IMS for residues and contaminant detection in food safety.To assess all the detected contaminants in food safety, for the first time.Identified IMS-related parameters and chemical compounds in food safety control.

Application of MIL-53(Al) prepared from waste materials for solid-phase microextraction of propranolol followed by corona discharge-ion mobility spectrometry (CD-IMS)

In this study, MIL-53(Al) metal-organic framework was prepared from waste raw materials. A polyethylene terephthalate (PET) plastic bottle was used as the source of terephthalic acid, and an aluminium beverage can was applied as the precursor of aluminium salt. The activated MIL-53(Al) was immobilized onto a stainless steel probe of the ion mobility spectrometer (IMS), and the coated probe was used for solid-phase microextraction of propranolol from biological samples before determination. The effect of the different parameters such as pH, ionic strength, and stirring rate of the sample, extraction time, and temperature was studied on the extraction efficiency of propranolol. The linearity was obtained ranging from 5-200 μg L^-1 with a determination coefficient (R²) of 0.9988, and the detection limit was calculated 1.7 μg L^-1 in the water sample. The relative standard deviations of the method were in the range of 2.5-12.2 %. Finally, the method was utilized for determination of propranolol in the tablet sample.

Recent Applications and Newly Developed Strategies of Solid-Phase Microextraction in Contaminant Analysis: Through the Environment to Humans

The present review aims to describe the recent and most impactful applications in pollutant analysis using solid-phase microextraction (SPME) technology in environmental, food, and bio-clinical analysis. The covered papers were published in the last 5 years (2014–2019) thus providing the reader with information about the current state-of-the-art and the future potential directions of the research in pollutant monitoring using SPME. To this end, we revised the studies focused on the investigation of persistent organic pollutants (POPs), pesticides, and emerging pollutants (EPs) including personal care products (PPCPs), in different environmental, food, and bio-clinical matrices. We especially emphasized the role that SPME is having in contaminant surveys following the path that goes from the environment to humans passing through the food web. Besides, this review covers the last technological developments encompassing the use of novel extraction coatings (e.g., metal-organic frameworks, covalent organic frameworks, PDMS-overcoated fiber), geometries (e.g., Arrow-SPME, multiple monolithic fiber-SPME), approaches (e.g., vacuum and cold fiber SPME), and on-site devices. The applications of SPME hyphenated with ambient mass spectrometry have also been described.

Novel sample preparation approaches in gas chromatographic analysis: Promising ideas

The development of sample preparation procedures is still a dynamic process despite a number of already proposed techniques. The main challenge in this research field is to fully replace classical procedures like liquid-liquid extraction and solid-phase extraction in gas chromatographic analysis. Some progress has been already achieved for the last 20 years when miniaturized techniques were incorporated in ISO standards. The current review is focused on novel approaches in sample treatment that appeared since 2010. It includes research studies describing non-conventional instrumental design available to inspire future progress in the field. A combination of a few extraction principles and supporting with additional treatment are the main core suggested for improvement of sample preparation efficiency. This requires good compatibility of extraction media, assessment of multiple experimental parameters, and potential automatization possibilities.

Coated direct inlet probe coupled with atmospheric-pressure chemical ionization and high-resolution mass spectrometry for fast quantitation of target analytes

The coated direct inlet probe (CDIP) is a new laboratory-made low-cost technology developed from a direct inlet probe (DIP), which has the advantage of quick enrichment/cleanup of an analyte from liquid samples. A capillary probe is coated with hydroxy-terminated polydimethylsiloxane (OH-PDMS), divinylbenzene (DVB), and β-cyclodextrin (β-CD) by a sol-gel method. This probe can be directly coupled with a commercialized atmospheric-pressure chemical ionization (APCI) ion source and high-resolution mass spectrometry, which are widely applicable, reliable, and durable. The ability to perform quantitative analyses with the use of a stable-isotope-labeled internal standard (SIL-IS) was tested by using different concentrations of acenaphthylene (ACY), acenaphthene (ACP), fluorene (FLR), fluoranthene (FLT), phenanthrene (PHE), and benzo[a]pyrene (B[a]P). Calibration curves with a coefficient of determination of R² ≥ 0.9982 for different polycyclic aromatic hydrocarbons (PAHs) were obtained. A limit of detection (LOD) of 0.008-0.04 ng mL^-1 for PAHs was determined. The entire workflow is solvent-free and can be completed in less than 5 min, which demonstrates the advantages of this technique for quantitative analysis.

Halloysite nanotubes in analytical sciences and in drug delivery: A review

Halloysite (HNT) is a natural inorganic mineral that has many applications in manufacturing. This review (with 192 references) covers (a) the chemical properties of halloysites, (b) the effects of alkali and acid etching on the loading capacity and the release behavior of halloysites, (c) the use of halloysite nanotubes in analytical sciences and drug delivery, and (d) recent trends in the preparation of magnetic HNTs. Synthetic methods such as co-precipitation, thermal decomposition, and solvothermal method are discussed, with emphasis on optimal magnetization. In the analytical field, recent advancements are summarized in terms of applications of HNT-nanocomposites for extraction and detection of heavy metal ions, dyes, organic pollutants, and biomolecules. The review also covers methods for synthesizing molecularly imprinted polymer-modified HNTs and magnetic HNTs. With respect to drug delivery, the toxicity, techniques for drug loading and the various classes of drug-halloysite nanocomposites are discussed. This review gives a general insight on the utilization of HNT in analytical determination and drug delivery systems which may be useful for researchers to generate new ideas. Graphical abstract Schematic presentation of the structure of halloysite nanotubes, selected examples of modifications and functionalization, and represetative field of applications.

Trace analysis by ion mobility spectrometry: From conventional to smart sample preconcentration methods. A review

Ion mobility spectrometry (IMS) is a rapid and high sensitive technique widely used in security and forensic areas. However, a lack of selectivity is usually observed in the analysis of complex samples due to the scarce resolution of the technique. The literature concerning the use of conventional and novel smart materials in the pretreatment and preconcentration of samples previous to IMS determinations has been critically reviewed. The most relevant strategies to enhance selectivity and sensitivity of IMS determinations have been widely discussed, based in the use of smart materials, as immunosorbents, aptamers, molecularly imprinted polymers (MIPs), ionic liquids (ILs) and nanomaterial. The observed trend is focused on the development of IMS analytical methods in combination of selective sample treatments in order to achieve quick, reliable, sensitive, and selective methods for the analysis of complex samples such as biological fluids, food, or environmental samples.

Nanotechnology-based recent approaches for sensing and remediation of pesticides

Pesticides are meant to control and destroy the pests and weeds. They are classified into different categories on the basis their origin and type of pest they target. Chemical pesticides such as insecticides, herbicides and fungicides are commonly used in agricultural fields. However, the excessive use of these agrochemicals have adverse effects on environment such as reduced population of insect pollinators, threat to endangered species and habitat of birds. Upon consumption; chemical pesticides also cause various health issues such as skin, eye and nervous system related problems and cancer upon prolonged exposure. Various techniques in the past have been developed on the basis of surface adsorption, membrane filtration and biological degradation to reduce the content of pesticides. However, slow response, less specificity and sensitivity are some of the drawbacks of such techniques. In recent times, Nanotechnology has emerged as a helping tool for the sensing and remediation of pesticides. This review focuses on the use of this technology for the detection, degradation and removal of pesticides. Nanomaterials have been classified into nanoparticles, nanotubes and nanocomposites that are commonly used for detection, degradation and removal of pesticides. The review also focuses on the chemistry behind the sensing and remediation of pesticides using nanomaterials. Different types of nanoparticles, viz. metal nanoparticles, bimetallic nanoparticles and metal oxide nanoparticles; nanotubes such as carbon nanotubes and halloysite nanotubes have been used for the detection, degradation and removal of pesticides. Further, various enzyme-based biosensors for detection of pesticides have also been summarized.

Improved analytical performance of photoionization ion mobility spectrometry for the rapid detection of organophosphorus pesticides using K0 patterns with multiple reactant ions

Ion mobility spectrometry (IMS) has become a potential technique for the rapid detection of organophosphorus pesticides (OPPs). However, using only the commonly-used reactant ion (Ac)₂H⁺(H₂O)_n, some OPPs are difficult to distinguish due to their severely overlapping ion peaks. In this study, the switching of reactant ions ((Ac)₂H⁺(H₂O)_n, O₂⁻(H₂O)_n and Cl⁻(H₂O)_n) in a stand-alone photoionization ion mobility spectrometer was realized by on-line switching the polarity of high voltage and dopant species. Multiple reactant ions were employed to establish the characteristic K₀ patterns for the tested OPPs, including fenthion, dursban, dimethoate, malathion, fenitrothion, imidan and isocarbophos. The tested OPPs were represented on a heat map and a three-dimensional coordinate system based on the K₀ patterns, from which they could be readily identified. Under optimal conditions, the limits of detection (LODs) of the tested OPPs were evaluated to be 0.3–2.7 ng, and satisfactory repeatability was demonstrated by the obtained relative standard deviations (RSDs) of 4.8% to 14.7%. Finally, Chinese cabbage extract spiked with dursban and malathion was detected by the proposed ion mobility spectrometer, demonstrating its applicability for the simultaneous identification of coexisting OPPs in real samples.

The identification of organophosphorus pesticides using ion mobility spectrometry was improved using K₀ patterns with multiple reactant ions.