Vortex-assisted matrix solid–liquid dispersive microextraction for the analysis of triazole fungicides in cotton seed and honeysuckle by gas chromatography

Dispersive magnetic solid phase extraction of triazole fungicides based on polybenzidine/magnetic nanoparticles in environmental samples

A polybenzidine-modified Fe3O4@SiO2 nanocomposite was successfully synthesized through a chemical oxidation method and employed as a novel sorbent in dispersive magnetic solid phase extraction (DMSPE) for the preconcentration and determination of three triazole fungicides (TFs), namely diniconazole, tebuconazole, and triticonazole in river water, rice paddy soil, and grape samples. The synthesis method involved a polybenzidine self-assembly coating on Fe3O4@SiO2 magnetic composite. Characterization techniques such as FT-IR, XRD, FESEM, EDX, and VSM were used to confirm the correctness of the synthesized nano-sorbent. The target TFs were determined in actual samples using the synthesized nanocomposite sorbent in combination with gas chromatography-flame ionization detection (FID). Several variables were carefully optimized , including the sample pH, sorbent dosage, extraction time, ionic strength, and desorption condition (solvent type, volume, and time). Under the optimized experimental conditions, the method exhibited linearity in the concentration range 5-1000 ng mL-1 for triticonazole and 2-1000 ng mL-1 for diniconazole and tebuconazole. The limits of detection (LOD) for the three TFs were in the range 0.6-1.5 ng mL-1. The method demonstrated acceptable precision with intra-day and inter-day relative standard deviation (RSD) values of less than 6.5%. The enrichment factors ranged from 248 to 254. Finally, the method applicability was evaluated by determining TFs in river water, rice paddy soil, and grape samples with recoveries in the range 90.5-106, indicating that the matrix effect was negligible in the proposed DMSPE procedure.

Simultaneous Determination of 147 Pesticide Residues in Traditional Chinese Medicines by GC-MS/MS

Determination of pesticide residues remains a challenge in traditional Chinese medicines in which complex compounds may interfere with analysis signals. This study reports the development of a simple, effective, and high-throughput method combining gas chromatography-tandem mass spectrometry (GC-MS/MS) with either QuEChERS or solid phase extraction (SPE) to determine 147 pesticide residues in traditional Chinese medicines simultaneously. In SPE, the mixture of n-hexane and ethyl acetate (1:1, v/v) was selected to extract 147 pesticides in honeysuckle, and the extracted pesticides were determined by GC-MS/MS. The limits of detection for all pesticides were within 0.01-0.05 mg/kg. The recoveries were within 70-120% and the relative standard deviations were below 20% for over 90% pesticides. The coefficients of determination were up to 0.999 for the linearity between MS signals and different concentrations of pesticides (20-200 ng/mL). The analytical performance was confirmed in determining pesticide residues in dried tangerine peel. SPE achieved comparable recoveries for all pesticides compared to the QuEChERS method.

Synthesis, X-ray Crystal Structure, Anticancer, Hirshfeld Surface Analysis, DFT, TD-DFT, ADMET, and Molecular Docking of 3-Phenyl-1,2,4-triazolo[3,4-h]-13,4-thiaza-11-crown-4

In this work, we describe the synthesis of new macrocycles derived from 3-phenyl-1,2,4-triazole-5-thione 1 in a heterogeneous medium using liquid–solid phase transfer catalysis (PTC) conditions. The structures of the two compounds (3 and 4) isolated were elucidated based on spectral data (1H-NMR, 13C-NMR) and confirmed in the case of 3-phenyl-1,2,4-triazolo [3,4-h]-13,4--thiaza-11-crown-4 (3) by a single-crystal X-ray diffraction analysis. Furthermore, the experimental spectral and the X-ray geometrical parameters were compared with their corresponding predicted ones obtained at the B3LYP/6-311++G(d,p) level of theory. The intercontacts between crystal units were investigated through Hirshfeld surface analysis. The drug-like macrocycles were predicted using ADMET and drug-likeness properties, which showed that 3 may act as an inhibitor of DNA-dependent protein kinase (DNA-PK). This assumption was confirmed by the well-binding fitting of 3 into the binding site of DNA-PK and the formation of a stable 3-DNA-PK complex with a binding energy of −7 kcal-mol−1. Finally, the anticancer activity of 3 was assessed by an MTT assay against A549 cells, which showed that 3 has moderate anticancer activity compared to that of the doxorubicin reference drug.

Ultrasound-assisted dispersive liquid-phase microextraction by solidifying L-menthol-decanoic acid hydrophobic deep eutectic solvents for detection of five fungicides in fruit juices and tea drinks

An ecofriendly and efficient ultrasound-assisted deep eutectic solvents dispersive liquid-phase microextraction by solidifying the deep eutectic solvents-rich phase was developed to determine azoxystrobin, fludioxonil, epoxiconazole, cyprodinil, and prochloraz in fruit juices and tea drinks by high-performance liquid chromatography. A varieties of environmental hydrophobic deep eutectic solvents serving as extraction agents were prepared using L-menthol and decanoic acid as hydrogen-bond acceptor and hydrogen-bond donor, respectively. The deep eutectic solvents were ultrasonically dispersed in sample solutions, solidified in a freezer and easily harvested. The main variables were optimized by one-factor-at-a-time and response surface test. The new method performs well with relative recovery of 71.75-109.40%, linear range of 2.5-5000 μg/L (r ≥ 0.9968), detection limit of 0.75-8.45 μg/L, quantification limit of 2.5-25 μg/L,_, and inter- and intraday relative standard deviations below 13.53 and 14.84%, respectively. As for the extraction mechanism, deep eutectic solvents were disposed into many fine particles in the solution and captured the analytes based on the changes of particle size and quantity in deep eutectic solvents droplets after extraction. The environmental method can successfully detect fungicide residues in real fruit juices and tea drinks.

Development of a method based on dispersive liquid-liquid microextraction followed by partial vaporization of the extract for ultra-preconcentration of some pesticide residues in fruit juices

A new simple and efficient method has been developed for the ultra-preconcentration of multiclass pesticide residues including penconazole, chlorpyrifos, ametryn, clodinafop-propargyl, diniconazole, oxadiazon, and fenpropathrin from some fruit juice samples based on evaporation of the sedimented organic phase obtained from dispersive liquid-liquid microextraction. The enriched target analytes were analyzed by gas chromatography-flame ionization detection. In the microextraction procedure, a mixture of iso-propanol as a disperser and 1,2-dibromoethane as an extraction solvent is quickly injected into an aqueous phase containing the analytes and centrifuged. Afterward, the sedimented phase is transferred into a special shaped vaporization vessel and vaporized with nitrogen gas stream until remaining about 2 µL of it. Eventually, 1 µL of the remained sedimented phase is removed and analyzed by separation system. The optimum extraction and disperser solvents were found to be 1,2-dibromoethane and iso-propanol, respectively. In addition, the optimum pH range was 6-8, and nitrogen gas stream at a flow rate of 90 mL min^-1 in a downward oriented vessel was applied. Eventually, the limits of detection and quantification were obtained in the ranges of 45-78 and 149-261 ng L^-1, respectively. Relative standard deviations at the concentrations of 300, 500 and 1000 ng L^-1 of each analyte were ranged between 2.2% and 5.8% for intra-day (n = 6) precision. Inter-day (n = 3) precision at a concentration of 500 ng L^-1 of each analyte was obtained in the range of 4.9-7.1%. In addition, enrichment factors and extraction recoveries were ranged from 1382-2246 and 55-89%, respectively. Finally, the method was successfully utilized in analysis of the target pesticides in the selected juices.

Application of liquid-phase microextraction to the analysis of plant and herbal samples

INTRODUCTION

The analysis of plant and herbal samples is a challenging task for analytical chemists due to the complexity of the matrix combined with the low concentration of analytes. In recent years different liquid-phase microextraction (LPME) techniques coupled with a variety of analytical equipment have been developed for the determination of both organic and inorganic analytes.

OBJECTIVE

Over the past few years, the number of research papers in this field has shown a markedly growing tendency. Therefore, the purpose of this review paper is to summarise and critically evaluate research articles focused on the application of LPME techniques for the analysis of plant and herbal samples.

RESULTS

Due to the complex nature of the samples, the direct application of LPME techniques to the analysis of plants has not often been done. LPME techniques as well as their modalities have been commonly applied in combination with other pretreatment techniques, including a solid-liquid extraction technique supported by mechanical agitation or auxiliary energies for plant analysis. Applications and the most important parameters are summarised in the tables.

CONCLUSION

This review summarises the application of the LPME procedure and shows the major benefits of LPME, such as the low volume of solvents used, high enrichment factor, simplicity of operation and wide selection of applicable detection techniques. We can expect further development of microextraction analytical methods that focus on direct sample analysis with the application of green extraction solvents while fully automating procedures for the analysis of plant materials.

Identification of key odorants in honeysuckle by headspace-solid phase microextraction and solvent-assisted flavour evaporation with gas chromatography-mass spectrometry and gas chromatograph-olfactometry in combination with chemometrics

At present, the identification of honeysuckle aroma depends on experienced tasters, which results in inconsistencies due to human error. The key odorants have the potential to distinguish the different species and evaluate the quality of honeysuckle. Hence, in this study, a more scientific approach was applied to distinguish various honeysuckles. The volatile compounds of different species and parts of honeysuckle were separately extracted by headspace-solid phase microextraction (HS-SPME) and solvent assisted flavor evaporation (SAFE). Compounds with greater volatility such as aldehydes, limonene, γ-terpinene, and terpinolene were preferentially extracted by HS-SPME. As a complementary extraction method to HS-SPME, SAFE was found to recover comparatively more polar compounds such as eugenol, decanoic acid, and vanillin. Subsequently, key odorants with the highest flavour dilution (FD) factors were detected by aroma extract dilution analysis (AEDA). These were benzaldehyde, 4-ethylphenol, decanoic acid, vanillin, 3-methyl-2-butenal, and β-ionone in honeysuckle flowers and γ-octalactone, 4-ethyl phenol, and vanillin in honeysuckle stem. Finally, principal component analysis (PCA) was conducted to analyze not only the key odorants of species and parts of honeysuckle but also their different origins. The results of PCA suggested that the species of honeysuckle contributed much more to variations in aroma rather than their origins. In conclusion, the application of the key odorants combined with PCA was demonstrated as a valid approach to differentiate species, origins, and parts of honeysuckle.

Compensation of matrix effects in seed matrices followed by gas chromatography-tandem mass spectrometry analysis of pesticide residues

Despite analytical advances, matrix effects (MEs) in pesticide residue analysis by gas chromatography - tandem mass spectrometry continue to be a challenge, especially in difficult samples such as seeds. In this study, the influence of different clean-up sorbents (chitin, chitosan, Z-Sep+, EMR-Lipid) and different mixtures of primary secondary amine (PSA), C18, graphitized carbon black (GCB) and MgSO₄ were investigated in terms of MEs and recoveries in four types of seeds: cress, fennel, flax, and hemp. Additionally, different volumes of water (5, 7.5 and 10 mL) were investigated for QuEChERS extraction. Under the selected conditions: the largest volume of water (10 mL) and PSA/C18/GCB/MgSO₄ (50/150/50/50 mg, respectively) as clean-up sorbent yielded acceptable recoveries of 70-120% for most of the pesticides (211-225 out of 248 compounds) and the lowest MEs were between -20%>MEs>20% (27-50 compounds). The final method was validated for 248 pesticides with LOQs equal to 0.005 mg kg^-1. Additionally, matrix-matched calibration was used as a practical method to compensate for MEs. Among the 21 pesticides found in 12 of the samples, chlorpyrifos (0.008-1.1 mg kg^-1), tebuconazole (0.071-0.96 mg kg^-1), and trifloxystrobin (0.007-0.15 mg kg^-1) were most commonly determined.

Dissipation and safety evaluation of afidopyropen and its metabolite residues in supervised cotton field

The novel insecticidal mechanism of afidopyropen can be substituted for traditional pesticides to control sap-sucking pests in cotton field. The data of residue amounts of afidopyropen and its metabolite M440I007 in cotton matrix and the environment soil are important to evaluate the safe use of the target compound and establish maximum residue limit (MRL). In this work, the dissipation and residue of afidopyropen and its metabolite M440I007 in cotton and field soils were investigated. The analytical methods of the target compound in cotton plants, cottonseed, crude cottonseed oil, cottonseed oil and soil were developed and quantified by high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS), which satisfied the rules of pesticide residue determination. The dissipation half-lives of afidopyropen in cotton plants and soil ranged from 1 to 3 days and 4-13 days, respectively. After 14 days from the last application, the residues of afidopyropen were below 0.01 mg/kg in cottonseed and were <0.005-0.0099 mg/kg in soil, and the residues of M440I007 were below 0.02 mg/kg in cottonseed and below 0.01 mg/kg in soil. The total national estimated daily intake (NEDI) of afidopyropen was 1.41 mg and the risk quotient (RQ) was 28.0%. The results showed that the risk of application of afidopyropen with the recommended dosage was acceptable.

Facile synthesis of magnetic zinc metal-organic framework for extraction of nitrogen-containing heterocyclic fungicides from lettuce vegetable samples

We present a simple method for the fabrication of a magnetic amino-functionalized zinc metal-organic framework based on a magnetic graphene oxide composite. The resultant framework exhibited a porous 3D structure, high surface area and good adsorption properties for nitrogen-containing heterocyclic fungicides. The adsorption process and capacity indicated that the primary adsorption mechanism might be hydrogen bonding and π-π conjugation. In addition, an optimized protocol for magnetic solid phase extraction was developed (such as adsorbent content, pH, and desorption solvent), and utilized for the extraction of nitrogen-containing heterocyclic fungicides from vegetable samples. Quantitation by high performance liquid chromatography coupled with tandem mass spectrometry offered a detection limit of 0.21-1.0 μg/L (S/N = 3) with correlation coefficients larger than 0.9975. These results demonstrate that magnetic amino-functionalized zinc metal-organic framewor is a promising adsorbent for the extraction and quantitation of nitrogen-containing heterocyclic fungicides.

Covalent Bonding of Metal-Organic Framework-5/Graphene Oxide Hybrid Composite to Stainless Steel Fiber for Solid-Phase Microextraction of Triazole Fungicides from Fruit and Vegetable Samples

A hybrid material of the zinc-based metal-organic framework-5 and graphene oxide (metal-organic framework-5/graphene oxide) was prepared as a novel fiber coating material for solid-phase microextraction (SPME). The SPME fibers were fabricated by covalent bonding via chemical cross-linking between the coating material metal-organic framework-5/graphene oxide and stainless steel wire. The prepared fiber was used for the extraction of five triazole fungicides from fruit and vegetable samples. Gas chromatography coupled with microelectron capture detector (GC-μECD) was used for quantification. The developed method gave a low limit of detection (0.05-1.58 ng g(-1)) and good linearity (0.17-100 ng g(-1)) for the determination of the triazole fungicides in fruit and vegetable samples. The relative standard deviations (RSDs) for five replicate extractions of the triazole fungicides ranged from 3.7 to 8.9%. The method recoveries for spiked fungicides (5, 20, and 50 ng g(-1)) in grape, apple, cucumber, celery cabbage, pear, cabbage, and tomato samples were in the range of 85.6-105.8% with the RSDs ranging from 3.6 to 11.4%, respectively, depending on both the analytes and samples. The metal-organic framework-5/graphene oxide coated fiber was stable enough for 120 extraction cycles without a significant loss of extraction efficiency. The method was suitable for the determination of triazole fungicides in fruit and vegetable samples.