[Determination of 222 pesticide residues in olive oil by fully automatic QuEChERS pre-treatment instrument coupled with gas chromatography-quadrupole-time-of-flight mass spectrometry].

Pesticide residues may be present in olive oil because pesticides are applied to olive trees during their cultivation and growth for pest prevention and some of these pesticides are not easily degraded. Studies on pesticide residues in olive oil have mainly focused on the detection of single types of pesticide residues, and reports on the simultaneous detection of multiple pesticide residues are limited. At present, hundreds of pesticides with different polarities and chemical properties are used in practice. In this study, an analytical method based on fully automatic QuEChERS pretreatment instrument coupled with gas chromatography-quadrupole time-of-flight mass spectrometry (GC-QTOF-MS) was established for the rapid determination of 222 pesticide residues in olive oil. The effects of acetonitrile acidification concentration, n-hexane volume, oscillation time, centrifugation temperature, and purification agent on the determination of the 222 pesticide residues were investigated. First, ions with good responses and no obvious interference were selected for quantification and characterization. The purification process was then developed by setting the parameters of the fully automatic QuEChERS pretreatment instrument to optimal values. The sample was extracted with acetonitrile containing 2% formic acid, and the supernatant was purified by centrifugation in a centrifuge tube containing 400 mg N-propylethylenediamine (PSA), 400 mg octadecylsilane-bonded silica gel (C18), and 1200 mg anhydrous magnesium sulfate. The purified solution was blown dry with nitrogen and then fixed with ethyl acetate for instrumental analysis. Finally, a matrix standard solution was used for quantification. The method was validated in terms of matrix effects, linear ranges, limits of detection (LODs) and quantification (LOQs), accuracies, and precisions. The results showed that 86.04% of the 222 pesticides had linear ranges of 0.02-2.00 µg/mL, 10.81% had linear ranges of 0.10-2.00 µg/mL, and 3.15% had linear ranges of 0.20-2.00 µg/mL. The pesticide residues showed good relationships within their respective linear ranges, and the correlation coefficients (R2) were greater than 0.99. The LODs of all tested pesticides ranged from 0.002 to 0.050 mg/kg, and their LOQs ranged from 0.007 to 0.167 mg/kg. Among the 222 pesticides determined, 170 pesticides had LOQs of 0.007 mg/kg while 21 pesticides had LOQs of 0.017 mg/kg. At the three spiked levels of 0.2, 0.5, and 0.8 mg/kg, 79.58% of all tested pesticides had average recoveries of 70%-120% while 65.92% had average recoveries of 80%-110%. In addition, 93.54% of all tested pesticides had relative standard deviations (RSDs, n=6)<10% while 98.35% had RSDs (n=6)<20%. The method was applied to 14 commercially available olive oil samples, and seven pesticides were detected in the range of 0.0044-0.0490 mg/kg. The residues of fenbuconazole, chlorpyrifos, and methoprene did not exceed the maximum limits stated in GB 2763-2021. The maximum residual limits of molinate, monolinuron, benalaxyl, and thiobencarb have not been established. The method utilizes the high mass resolution capability of TOF-MS, which can improve the detection throughput while ensuring good sensitivity. In addition, high-resolution and accurate mass measurements render the screening results more reliable, which is necessary for the high-throughput detection of pesticide residues. The use of a fully automatic QuEChERS instrument in the pretreatment step reduces personnel errors and labor costs, especially when a large number of samples must be processed, thereby offering significant advantages over other approaches. Moreover, the method is simple, rapid, sensitive, highly automatable, accurate, and precise. Thus, it meets requirements for the high-throughput detection of pesticide residues in olive oil and provides a reference for the development of detection methods for pesticide residues in other types of oils as well as the automatic pretreatment of complex matrices.

Development and validation of a deep eutectic solvent-assisted liquid-liquid extraction method for simultaneous quantification of six steroid hormones in serum by liquid chromatography-tandem mass spectrometry.

Steroid hormones have been reported to be associated with endocrine system diseases. This paper proposes a novel procedure of deep eutectic solvent (DES)-assisted liquid-liquid extraction (LLE) to extract six steroid hormones (including cortisone, cortisol, androstenedione, testosterone, 17-hydroxyprogesterone, and progesterone) from serum coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS). A total of five types of L-proline, choline chloride, and citric acid-based DESs were tailored; the DES from L-proline and ethylene glycol at a molar ratio of 1:4 with 20 % acetonitrile was selected as the best-fit assisted solvent for the six steroid hormones compared with other DESs. The parameters for extraction by selected DES were optimized using Box-Behnken design (BBD), and the optimal extraction conditions are 200 µL of acetonitrile, 100 µL of the sample, and 80 µL of DES. Under optimum conditions, the method has good linear calibration ranges (between 0.07 ng mL-1 and 600 ng mL-1), correlation coefficients of determination (r2>0.99), and low limits of quantification (between 0.02 and 0.60 ng mL-1). The extraction recoveries were in the range of 81.84-114.43 %, and the intra-day and inter-day relative standard deviations (RSDs) were less than 10 %.In general, the DES-LC-MS/MS method is a simple and environmentally-friendly method, which can be complementary to the presently available methods for determining steroid hormones in serum.

Method validation for detection of afidopyropen and M440I007 in tea.

BACKGROUND: Afidopyropen is a novel biorational insecticide for controlling piercing pests with great potential for application in tea gardens that can form the metabolite M440I007 when utilized for crops. However, because of a lack of analytical method for afidopyropen and M440I007 in tea, there is no means of monitoring the residues. Therefore, method development, validation and simultaneous determination of afidopyropen and M440I007 in fresh tea leaves, dried tea and tea infusion is of prime significance. RESULTS: A TPT cartridge-based method was developed for the solid phase extraction of afidopyropen and M440I007 from tea matrices. Extraction and clean-up conditions, including the composition, volume and temperature of elutions, were optimized to achieve the best results. Both targets were extracted using water and acetonitrile, with a water:acetonitrile (v/v) ratio of 4:10 for fresh leaves and 8:10 for dried tea, which were then cleaned and analyzed using ultraperformance liquid chromatography-tandem mass spectrometry. Both analytes demonstrated excellent linearity with a correlation coefficient above 0.998. The optimized analytical method offered limits of quantifications of 0.005, 0.005 and 0.002 mg kg-1 (converted to dried tea) in fresh tea shoots, dried tea and tea infusion for both targets, respectively. Average recoveries of afidopyropen and M440I007 ranged from 79.0% to 101.5%, with relative standard deviations ≤ 14.7%. CONCLUSION: The results showed that the method of determination for these insecticides in tea matrices was practical and efficient. © 2023 Society of Chemical Industry.

[Determination of 18 caine anesthetics in animal meat using solid phase extraction combined with ultra-performance liquid chromatography-tandem mass spectrometry].

Because of the widespread application of anesthetic drugs in the fields of animal breeding and transportation, demand for the rapid, sensitive detection of anesthetic drugs in animal meat is increasing. The complex animal meat matrix contains various interfering substances, such as proteins, fats, and phospholipids, along with anesthetic drug residues at very low concentrations. Therefore, adopting appropriate pretreatment methods is necessary to improve the sensitivity of detection. In this study, a rapid, accurate analytical method based on ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) and solid phase extraction (SPE) was established to determine the contents of 18 caines in animal meat. The MS parameters, such as the collision energies of 18 caines, were optimized. Furthermore, the chromatographic separation conditions and response intensities of the caine in different mobile phases were compared. The effects of different pretreatment conditions on the extraction efficiencies of the 18 caines in meat samples and those of different purification conditions, such as extraction solvent, SPE column, and dimethylsulfoxide (DMSO) dosage, on their recoveries were investigated. Combined with the external standard method, the 18 caines in meat were successfully quantified. Sample pretreatment is a three-step process. First, in ultrasound-assisted extraction, 2.0 g samples were added to 2.0 mL water and extracted using 10 mL 0.1% (v/v) formic acid in acetonitrile under ultrasound conditions for 10 min. SPE was then performed using an Oasis PRIME HLB column. Finally, DMSO-assisted concentration was employed: the organic layer was collected and dried at 40 ℃ under a stream of N2 gas with the addition of 100 µL DMSO. Acetonitrile-water (1∶9, v/v) was added to the residue to yield a final volume of 1.0 mL for use in UPLC-MS/MS. The 18 caines were separated using an HSS T3 (100 mm×2.1 mm, 1.8 µm) column with 0.1% (v/v) formic acid in water (containing 0.02 mmol/L ammonium acetate) and methanol as mobile phases. Samples were detected using an electrospray ion source (ESI) in the positive ion and multiple reaction monitoring (MRM) modes during UPLC-MS/MS. Under the optimized conditions, the 18 target caine anesthetics displayed good linearities in the range of 1.00-50.0 µg/L, and the correlation coefficients (R2) were >0.999. The respective limits of detection (LODs) and quantification (LOQs) were 0.2-0.5 µg/kg, and 0.6-1.5 µg/kg. In pork, beef, and mutton samples, the recoveries obtained at three spiked levels were 83.4%-100.4% with relative standard deviations (RSDs) of 3.1%-8.5%. This simple, rapid, sensitive method may be applied in the detection of 18 caine anesthetics in animal meat and may provide technical support to the food safety department in China in monitoring the residues of caine anesthetics in animal meat.

Multiresidue extraction of current-use pesticides from complex solid matrices using energized dispersive guided extraction with analysis by gas and liquid chromatography tandem mass spectroscopy.

The development of sample processing techniques that recover a broad suite of pesticides from solid matrices, while mitigating coextracted matrix interferences, and reducing processing time is beneficial for high throughput analyses. The objective of this study was to evaluate the effectiveness of an automated extraction system for pesticide analyses in solid environmental samples. An Energized Dispersive Guided Extraction (EDGE) system was used to evaluate two different extraction solvents in optimizing the extraction of 210 pesticides and pesticide transformation products. A graphitized carbon cleanup step was implemented, and three elution solvents were evaluated separately for analyte recoveries. Recoveries between 70 and 130% were achieved for 167 compounds in a test soil using acetonitrile as an extraction solvent and carbon cleanup with acetonitrile and dichloromethane elutions. Nine field samples (soil, sediment, and biosolids) were extracted using the newly developed method and were compared with a previously validated pressurized liquid extraction (PLE) method using an Accelerated Solvent Extraction (ASE) system. Concentrations obtained from the two methods were comparable (linear R2 > 0.999), suggesting similar performance between the EDGE and PLE extractions in complex matrices. The new method provided slightly better sensitivities in comparison to the PLE method, ranging from 0.09 to 2.56 ng g-1. The method presented here significantly reduces extraction setup and runtimes while also minimizing the volume of carcinogenic solvents (e.g., dichloromethane) used in the laboratory and presents a sensitive multiresidue method for a wide range of pesticides in solid matrices.

Development and optimization of an ultra-fast microextraction followed by HPLC-UV of tetracycline residues in milk products.

The present study developed a new ultra-fast microextraction (within 8 min) with acetonitrile followed by gradient reversed-phase HPLC-UV method to determinate six tetracyclines simultaneously in various milk products with HPLC analysis time of 9 min. Chromatographic separations were achieved with a phenomenex™ Synergi 4 µm Fusion-RP (150 × 4.60 mm) column at 220 nm, using acetonitrile/KH2PO4 buffer (4 mmol·L-1, pH 2.5) as mobile phase. The HPLC method showed excellent peak resolutions (3.3-8.8) and peak symmetry (0.99-1.11) inspite of short analysis time. The extraction rates from milk products showed consistently very good values over all tetracyclines (milk 80.58 ± 5.39 %, yoghurt 82.61 ± 5.63 %, cream cheese 80.13 ± 6.32 %, buttermilk 81.07 ± 6.49 %, kefir 79.69 ± 6.51 %, skyr 78.12 ± 5.22 %, quark 65.37 ± 4.72 %). The optimized method was found to be specific, reproducible, robust. This study combines for the first time a fast, cheap quantification of six tetracyclines via HPLC-UV with a reliable microextraction applicable to various milk products using only standard laboratory equipment.

[Determination of three penicillin residues in milk by solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry using a covalent triazine framework sorbent].

A method based on solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS) was established for the determination of gpenicillin, cloxacillin, ampicillin residues in milk. Using self-made covalent triazine frameworks (CTFs) as the solid-phase extraction sorbents, the main factors influencing the efficiency of the solid-phase extraction columns, such as the sorbent amount, eluent type, eluent volume, and flow rate, were optimized. The extraction and purification conditions for the samples were also investigated. The optimal extraction effect was achieved at a flow rate of 3 mL/min with 60 mg CTFs and 6 mL eluent solution (acetonitrile). Separation was carried out on a Waters ACQUITY UPLC BEH C18 column, and 0.1% formic acid aqueous solution-acetonitrile was used as the mobile phases for gradient elution. The filtrate was detected by ultra performance liquid chromatography-tandem mass spectrometry, identified by electrospray ionization (ESI) in the positive mode using multiple reaction monitoring, and quantified using external standards. The calibration curves of the three penicillins showed good linearity and the correlation coefficients of the linear regression equations for the three target analytes were all greater than 0.999. The limits of detection (LODs) and limits of quantification (LOQs) were 0.05-0.10 µg/kg and 0.1-0.4 µg/kg, respectively. The average recoveries of the three analytes were 84.9%-94.1%, and the relative standard deviations (RSDs, n=5) were 1.66%-3.27%. Moreover, the mechanism of interaction between the CTFs and the target analytes was analyzed. The results revealed the existence of π-π and hydrogen-bond interactions between the CTFs and analytes. The results further indicated that the CTFs could be successfully used for the enrichment and purification of penicillins in milk. The proposed method has the advantages of high precision, good reproducibility, high resolution, and short analysis time, and it is suitable for the qualitative and quantitative determination of trace targets in complex matrices.

[Rapid determination of 16 polycyclic aromatic hydrocarbons in atmospheric fine particles by molecularly imprinted column-high performance liquid chromatography].

OBJECTIVE: A high performance liquid chromatographic method based on the purification of polycyclic aromatic hydrocarbon molecularly imprinted columns was developed, this method was used for the rapid quantitative determination of 16 polycyclic aromatic hydrocarbons(PAHs) in fine particulate matter(PM_(2.5)). METHODS: The polycyclic aromatic hydrocarbons of the sample were extracted with acetonitrile ultrasonically, purified by molecular imprinting column(MIP-PAHs), and tested after being concentrated by nitrogen blowing. RESULTS: The 16 PAHs showed a good linear relationship in the range of 1-40 ng/mL, and the correlation coefficient r>0.9996; the recoveries were 77.13%-107.67% at the three standard addition levels of 5.0, 10.0 and 20.0 ng/mL, the relative standard deviation was 0.15%-4.63%(n=7); the detection limit of the method was 0.004-0.078 ng/m~3, and the quantification limit was 0.016-0.336 ng/m~3. CONCLUSION: The detection of 16 PAHs in PM_(2.5) using this method is more accurate, more sensitive and less time consuming than the result of the simple ultrasonic extraction method and the Soxhlet extraction method in Determination of PAHs in ambient air and exhaust gases in gas phase and particulate matter by high performance liquid chromatography(HJ 647-2013).

[Polyamidoamine dendrimer-functionalized silica nanocomposite with polydopamine coating for dispersive micro solid-phase extraction of benzoylurea insecticides in water samples].

Pesticides are used in the agricultural production process to ensure the yield and quality of agricultural products. However, in recent years, environmental pollution issues caused by pesticide residues have sparked widespread concern in society. It is important to develop convenient and efficient approaches to detect and monitor pesticide residues. In this study, targeting benzoylurea insecticides (BUs), polyamidoamine dendrimer-functionalized silica nanocomposite with polydopamine coating (SiO2-PAMAM-PDA) was designed and successfully synthesized. First, monodisperse silica nanoparticles were prepared by the hydrolysis of tetraethyl orthosilicate (TEOS) in mixed solution of ethanol, water and ammonia. The silane coupling agent (3-aminopropyl)triethoxysilane was then employed to introduce amino groups into the silica. Silica with the zeroth generation of polyamidoamine (PAMAM) modification (SiO2-PAMAM-G0) was obtained through Michael addition reaction of methyl acrylate. Ethylenediamine was added to polymerize with methyl acrylate using an amidation reaction to form the first-generation PAMAM (SiO2-PAMAM-G1). Finally, by polymerizing dopamine under alkaline conditions (pH=8.5), the SiO2-PAMAM-G1 was coated with PDA. Thus, the final product named SiO2-PAMAM-PDA was obtained. The composite was characterized using a transmission electron microscope (TEM) and an increase in surface roughness indicated the successful grafting of PDA coating. Dopamine structure contains abundant benzene rings and amino and hydroxyl groups. It could bind with BUs through multiple secondary interactions, such as hydrogen bond and π-π stacking interaction. Therefore, the introduction of PDA could effectively enhance the affinity of the material toward benzoylurea insecticides. The prepared nanocomposites were used as sorbents in a dispersive micro solid-phase extraction approach (D-µ-SPE). The established approach was employed to extract and enrich the BUs in water samples before high-performance liquid chromatography (HPLC) analysis. Diflubenzuron, triflumuron, hexaflumuron, and teflubenzuron were chosen as target analytes. The following was a typical D-µ-SPE procedure. The prepared adsorbents measuring 40 mg were first dispersed in an 8-mL sample solution containing 150 g/L NaCl. The dispersion was assisted by 120-s vortexing to ensure full contact between the SiO2-PAMAM-PDA and the targets. Next, the adsorbents were separated from the liquid phase by 4-min centrifugation (5000 r/min). Thereafter, the adsorbed benzoylureas were eluted using 1 mL acetonitrile as desorption solvent by 120-s vortexing. Separated by centrifugation, the eluate was dried under a mild nitrogen stream. The solid remains were redissolved in 0.1 mL of acetonitrile, filtered by filter membrane (0.22 µm), and then analyzed by HPLC. The experimental conditions in the D-µ-SPE process could have a great impact on the extraction efficiency. Experimental conditions were optimized using a single factor optimization approach to further enhance the extraction recoveries. The optimized conditions included adsorbent amount, extraction time, desorption solvent type, desorption solvent volume, desorption time, and NaCl addition amount. Under the optimal conditions, a linearity range of 10-500 µg/L and limits of detection (LODs, S/N=3) of 1.1-2.1 µg/L were obtained. The extraction recoveries and relative standard deviations (RSDs) of the four BUs were 82.8%-94.1% and 2.1%-8.0%, respectively. The established approach was compared with reported approaches targeting benzoylurea insecticides. It was discovered that this approach consumed less sample, material, organic solvent, and pretreatment time. It provided a more rapid and green choice for the determination of benzoylurea pesticides. To determine the applicability, the proposed approach was applied to analyze the four benzoylurea insecticides in three river water samples. The real water samples were pretreated using the developed approach ahead of instrumental analysis, and no benzoylurea pesticides residue was detected. Next, standard addition experiments were performed under three spiking levels, including 15, 50, and 200 µg/L. The established approach had good accuracy and feasibility with satisfactory recoveries (69.5%-99.4%) and RSDs (0.2%-9.5%).

Simple and rapid method for 336 multiresidual pesticide analysis in saliva, determination of their chemical stabilities, and biomonitoring of farmers.

Simultaneous multiresidual pesticide analysis of saliva samples was performed using scaled-down QuEChERS extraction with LC-MS/MS and GC-MS/MS. The optimum extraction procedure using acidified acetonitrile was applicable to 336 pesticides (287 for LC-MS/MS and 49 for GC-MS/MS). To determine pesticide multiresidues in saliva, 100 µL of the sample was extracted with 200 µL of 0.1% formic acid in acetonitrile, and the initial extract was partitioned with 40 mg of MgSO4 and 10 mg of NaCl. The organic supernatants (120 µL) were then mixed with acetonitrile (30 µL) for matrix-matching (4:1, v/v), and the final extract solution was injected into the LC-MS/MS (4 µL) and GC-MS/MS (2 µL) systems. The established analytical method showed a good LOQs between 5 and 25 ng/mL with reliable accuracy/precision values and recovery results (50-140%) for the target pesticides. Under the two different storage conditions, most of the analytes did not undergo chemical changes in the saliva samples, whereas some pesticides were more stable in freeze-thaw processes than those left at room temperature. Biomonitoring of farmers (ten mixers and ten sprayers) was successfully applied using the validated method, and two carbamates (fenobucarb and propamocarb) were determined at trace concentrations (12.5-675.0 ng/mL from 11 positively detected samples).

Acyl-Nω-methylserotonins and Branched-chain Acylserotonins in Lemon and Other Citrus Seeds-New Lipids with Antioxidant Properties and Potential Pharmacological Applications.

We have found 15 previously unknown compounds in seeds of lemon and other citrus species, such as tangerine, grapefruit and pomelo. The structure of these compounds was characterized by HR-MS spectrometry, fluorescence spectroscopy and chemical synthesis. These compounds were predominantly long-chain (C20-C25), saturated acyl-Nω-methylserotonins with the main contribution of C22 and C24 homologues, usually accounting for about 40% and 30% of all acylserotonins, respectively. The other, previously undescribed, minor compounds were branched-chain acylserotonins, as well as normal-chain acylserotonins, recently found in baobab seed oil. Within the seed, acylserotonins were found nearly exclusively in the inner seed coat, where probably their biosynthesis proceeds. On the other hand, lemon seedlings contained only trace amounts of these compounds that were not found in adult leaves. The compounds identified in the present studies were shown to have antioxidant properties in vitro, using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay. In the investigated reaction in hexane, Me-C22 and Me-C24-serotonins were less active than n-C22 and n-C24-serotonins and δ-tocopherol, while branched-chain acylserotonins (iso-C21 and -C25) showed higher antioxidant activity than all the normal-chain compounds. On the other hand, all these compounds showed a similar but considerably lower antioxidant activity in acetonitrile than in hexane.

Determination of Cyclaniliprole in Fruits and Vegetables Using Disposable Pipette Extraction Cleanup and Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Despite an outstanding agent for control of Lepidoptera, the diamide insecticide cyclaniliprole (CYCP) is a suspected carcinogen. In the present study, an analytical method was developed for the determination of CYCP in six fruits and vegetables (apple, grape, peach, bell pepper, lettuce, and tomato) using ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry. Sample preparation was carried out by the acetonitrile-salting-out extraction followed by simple and fast cleanup of disposable pipette extraction tip containing styrene divinyl benzene and/or graphitized carbon black. Satisfactory linearity (r > 0.99) was obtained in the calibration range of 0.001−1 µg mL−1. Matrix effects decreased from −9.9−−17.9% to −1.0−−7.6% after the cleanup. The recoveries of CYCP at three spike levels (0.01, 0.1, and 1 mg kg−1) from different matrices were between 75.7% and 111.5%, with the intra-day (n = 5) and inter-day (n = 15) relative standard deviations lower than 12.1%. The limit of quantification was 0.01 mg kg−1. The developed method provides a good reference for routine monitoring of CYCP in these fruits and vegetables.

Synthesis and Characterization of Newly Designed and Highly Solvatochromic Double Squaraine Dye for Sensitive and Selective Recognition towards Cu2.

Synthesis and characterization of a novel and zwitterionic double squaraine dye (DSQ) with a unique D-A-A-D structure is being reported. Contrary to the conventional mono and bis-squaraine dyes with D-A-D and D-A-D-A molecular frameworks reported so far, DSQ dye demonstrated strong solvatochromism allowing for the multiple ion sensing using a single probe by judicious selection of the suitable solvent system. The DSQ dye exhibited a large solvatochromic shift of about 200 nm with color changes from the visible to NIR region with metal ion sensitivity. Utilization of a binary solvent consisted of dimethylformamide and acetonitrile (1:99, v/v), highly selective detection of Cu2+ ions with the linearity range from 50 µM to 1 nM and a detection limit of 6.5 × 10-10 M has been successfully demonstrated. Results of the Benesi-Hildebrand and Jobs plot analysis revealed that DSQ and Cu2+ ions interact in the 2:1 molecular stoichiometry with appreciably good association constant of 2.32 × 104 M-1. Considering the allowed limit of Cu2+ ions intake by human body as recommended by WHO to be 30 µM, the proposed dye can be conveniently used for the simple and naked eye colorimetric monitoring of the drinking water quality.

Green and Efficient Determination of Fluoroquinolone Residues in Edible Green Fruits and Leafy Vegetables by Ultrasound-Assisted Extraction Followed by HPLC-MS/MS.

In this work, a simple, quick and efficient analytical method for determination of human and veterinary fluoroquinolone antimicrobial residues in lettuce, cucumber and spinach is developed. The procedure entails a 6 min ultrasound-assisted extraction (UAE, 3 × 2 min) in an alkaline (2% v/v NH3) aqueous solution containing Mg2+ ions (3 × 6 mL), with no need for organic solvents. The extract is submitted to cleanup on the HLB™ cartridge and the fluoroquinolones are separated and quantified by HPLC-MS/MS in a 10 min chromatographic run, using a small amount of acetonitrile in the mobile phase. The method, entirely developed in real matrices, is validated according to the updated analytical guidelines and provided suitable recoveries in the range of 67-116% and precision (RSD ≤ 20%, n = 3) at different concentrations (15, 70 and 150 ng g-1), with method quantification limits of 2-10 ng g-1. Fluoroquinolones were detected and quantified at concentrations from few to hundreds of nanograms per gram in vegetables from supermarkets, demonstrating the applicability of the method for monitoring residues of these pharmaceuticals.

[Rapid determination of 22 functional components in cosmetics using ultra-high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry].

Plant components from extracts of Sophora flavescens, rhodiola, ginseng, Centella asiatica, and tea play important roles in skin whitening, moisturizing, anti-aging, sun protection, anti-inflammation, antiseptic, bacteriostatic, and other effects of cosmetics. At present, no relevant standard methods have been established to detect the addition amounts of plant extracts in cosmetics. In addition, plant extracts listed in product labels may be undetectable due to their addition in trace quantities and the lack of technical support. Therefore, a quantitative method for the simultaneous determination of 22 functional components in cosmetics was established by ultra-high performance liquid chromatography-linear ion trap/orbitrap high resolution mass spectrometry (UHPLC-LTQ/Orbitrap MS). Target compounds were extracted with methanol from samples using ultrasonic extraction, and then separated on a C18 column (100 mm × 2.1 mm, 1.8 µm) with gradient elution of 0.1% (v/v) formic acid aqueous solution (A) and acetonitrile (B). The gradient elution program were as follows: 0-5 min, 5%B-8%B; 5-25 min, 8%B-60%B; 25-35 min, 60%B-80%B; 35-36 min, 80%B-5%B; 36-45 min, 5%B. The flow rate was 0.3 mL/min and the injection volume was 5 µL. Accurate masses of precursor ions were used to detect cosmetic functional components in positive ionization mode. The fragment ions obtained by higher energy collisional dissociation were used for confirmation of the functional components. Each compound showed good linearity. The limits of detection (LODs) were in the range of 0.003-2.01 mg/kg, and the limits of quantification (LOQs) were in the range of 0.02-4.36 mg/kg. Recoveries at three levels were 63.2%-125.1%, and relative standard deviations (RSDs) were 0.18%-10.9%. Fifty-four batches of samples labeled with four monomer functional components and nine plant extracts were tested. In the 17 batches of samples labeled with nicotinamide, 4 batches labeled with caffeine, and 6 batches labeled with Sophora flavescens root extract, the labeled functional components were detected. One out of 11 batches of samples labeled with D-panthenol was not detected. Three of the seven batches of samples labeled with ascorbyl glucoside were not detected. In the 21 batches of samples labeled with licorice extracts, the corresponding functional components were not detected in 9 batches. In the 21 batches of samples labeled with Centella asiatica extract, the corresponding functional components were not detected in 11 batches. In the 13 batches of samples labeled with tea extract, the corresponding functional components were not detected in 8 batches. In 11 of the 12 batches containing ginseng root extract, the corresponding functional components were not detected. In five of the six batches of astragalus membranaceus root extract samples, the corresponding functional components were not detected. In samples labeled with Polygonum cuspidatum root extract, Rehmannia glutinosa root extract, and Ophiopogon japonicus root extract, the corresponding functional components were detected. The method is simple, rapid, reliable, accurate, and suitable for the determination of the 22 functional components in cosmetics.

[Separation and enrichment of trace aflatoxin B1 in grains by magnetic nanomaterials based on SiO2@Fe3O4].

In this study, a magnetic nanomaterial antibody (Ab)-SiO2@Fe3O4 was synthesized, which was employed to absorb aflatoxin B1 (AFB1) in complicated grain matrices. The Ab-SiO2@Fe3O4 material was then paired with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) for subsequent accurate detection. The Ab-SiO2@Fe3O4 material has a specific adsorption capacity for AFB1 because of the stable and specific biological binding between antigen and antibody. This process can achieve the identification between the material and food matrix quickly, thereby completing the separation and enrichment process. Then, high sensitivity and high accuracy HPLC-MS/MS were employed for signal readout and actual quantification, which can significantly increase the detection efficiency and enable high-throughput detection of numerous samples. In the pretreatment process, Fe3O4 was first synthesized by microwave-assisted hydrothermal synthesis within 1 h, and Ab-SiO2@Fe3O4 was then produced using the enhanced Stober's approach. This material with high adsorption performance was synthesized under relatively mild conditions and short time. To obtain Ab-SiO2@Fe3O4 materials with uniform particle size, magnetic properties, and dispersibility that met the requirements, synthesis conditions of Ab-SiO2@Fe3O4 and conditions for capturing the AFB1 target were analyzed. The findings demonstrated that the best effect was obtained when the dosage of FeCl3·6H2O was 10.0 mmol, the heating time was 40 min, and 100 µL tetraethoxysilane was employed for SiO2 coating. The AFB1 antibody was then combined with the surface of SiO2@Fe3O4 under several conditions. The findings revealed that the best coupling efficiency of Ab could be obtained when the concentration of 2-morpholinoethanesulfonic acid monohydrate (MES) was 10 mmol/L, pH was 6.5, and the molar ratio of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC)∶N-hydroxysuccinimide substances (NHS) was 2∶1. The coupling buffer was then selected as phosphate buffer (PBS) with pH=7.4, and 8 mg Ab-SiO2@Fe3O4 was employed to separate and enrich AFB1 at 37 ℃ for 10 min. In the actual detection, acetonitrile-water-formic acid (85∶10∶5, v/v/v) was employed as the extraction solution. After ultrasonic extraction for 10 min, Ab-SiO2@Fe3O4 was employed to separate and enrich AFB1 in the extract. The supernatant was dried with nitrogen and reconstituted with 1-mL acetonitrile. The solution was then filtered through a 0.22 µm filter and detected using HPLC-MS/MS, thereby realizing the quick and quantitative detection of AFB1. AFB1 had an excellent linear relationship in the range of 2-50 µg/L under the optimal analytical conditions, and the correlation coefficient was less than 0.99. The LOD was 0.04 µg/kg, and the LOQ was 0.13 µg/kg. The spiked recoveries of AFB1 in three grain matrices ranged from 76.21% to 92.85% with RSD≤5.29% at four different spiked levels. The approach was applied to the determination and analysis of AFB1 in 30 real grain samples of rice, corn, and wheat. The findings demonstrated that AFB1 was detected in one wheat sample and two corn samples, and its content was 0.38, 0.13, and 0.47 µg/kg, respectively, and no toxins were found in other samples. The approach combined Ab-SiO2@Fe3O4 magnetic nanomaterials with HPLC-MS/MS, which could obtain high-efficiency separation and enrichment of AFB1. Furthermore, the low-cost Ab-SiO2@Fe3O4 could be stored for more than a week and complete the pretreatment process within 30 min. This effective pretreatment process combined with HPLC-MS/MS could realize the analysis of several samples within a short time, and had a promising application prospect in the detection of AFB1 in grains.

Simultaneous enantioselective determination of two succinate- dehydrogenase-inhibitor fungicides in plant-origin foods by ultra-high performance liquid chromatography-tandem mass spectrometry.

Fluindapyr and penthiopyrad are two new succinate-dehydrogenase-inhibitor fungicides both employed as racemic mixtures of enantiomers to control various fungal pathogens. In the present work, a robust and highly-sensitive method for simultaneous determination of fluindapyr and penthiopyrad enantiomers in plant-origin foods (cereals, fruits and vegetables) was developed using UPLC-MS/MS combined with a chiral stationary phase. Rapid baseline chiral separation of four stereoisomers of fluindapyr and penthiopyrad was obtained within 4.2 min on chiral MX(2)-RH column under reversed-phase conditions (with the eluent of acetonitrile/0.1% formic acid in water =70/30 (V:V) and column temperature maintained at 30 °C). The plant-origin samples were extracted quickly with acetonitrile and purified with multi-walled carbon nanotubes. Excellent linearity for the target analytes was observed in the concentration ranging from 1 to 250 µg/L with regression coefficient no less than 0.9967. The mean recoveries of fluindapyr and penthiopyrad enantiomers from six matrices were 77.1-107.2%, with all relative standard deviations values lower than 9.1%. The limit of quantification of four stereoisomers of two target chiral fungicides was 5 µg/kg. The analysis of real samples reveal that the developed method is suitable for the simultaneous chiral determination of fluindapyr and penthiopyrad residues in cereals, fruits and vegetables samples at enantiomeric level and can support their further investigation on enantioselective environmental behaviors and residue surveillance.

[Rapid screening of 84 pesticide residues in dendrobium by Sin-QuEChERS Nano purification column with gas chromatography-tandem mass spectrometry].

A rapid screening method for 84 pesticide residues in dendrobium perfringens parent material with different polarities was developed using a Sin-QuEChERS Nano clean-up column combined with gas chromatography-tandem mass spectrometry (GC-MS/MS). The differences in extraction efficiency of the targets were compared with different extraction solvents (acetonitrile containing 1% acetic acid, acetone) and methods (immersion with or without water). The purification effect and extraction recoveries of Sin-QuEChERS Nano method and classical dispersive solid-phase extraction (dSPE), solid-phase extraction (SPE) and QuEChERS were systematically compared using Dendrobium nobile samples. The differences in matrix effects between the Sin-QuEChERS Nano method, which was more effective in purification, and the dSPE method were also analyzed. The purification effects of three commercially available Sin-QuEChERS Nano purification columns (simple matrix purification column, complex matrix purification column and herbal purification column) were compared. The applicability of the purification methods were also verified by using different parts of Dendrobium nobile samples (stems, leaves and flowers). From the results, it could be concluded that weighing 2.00 g and the samples in 5 mL of water for 20 min, followed by extraction with acetonitrile containing 1% acetic acid was more effective. The average extraction recovery of the target components by Sin-QuEChERS Nano purification method was 90.5%, which further identified Sin-QuEChERS Nano-Chinese medicine purification column as the preferred purification column for dendrobium purification. The target components were separated by a DB-1701MS quartz capillary column (30 m×0.25 mm×0.25 µm) with programmed temperature rise, detected by multiple reaction monitoring (MRM) mode, and quantified by matrix-matched solution external standard method. The GC-MS/MS assay was used for the methodological validation of the 84 representative pesticides within Dendrobium officinale and Dendrobium nobile was carried out by GC-MS/MS detection method. The results indicated that the targets showed excellent linear correlation in different scopes with correlation coefficients (r2) >0. 990. The limits of detection (LODs, S/N=3) of the method were 1.5 to 5.8 µg/kg, and the limits of quantification (LOQs, S/N=10) ranged from 5.0 to 15.0 µg/kg. The spiked recoveries of the target pesticides under different spiked levels were 68.7%-116.2%, and the relative standard deviations (RSDs, n=6) were less than 15%. Compared to other typical pretreatment methods, the Sin-QuEChERS Nano method provided better performance in terms of purification. The method not only effectively removed pigments, organic acids, and alkaline interferents, but also saved preparation time. Losses due to solvent transfer were also avoided and no further vortexing or centrifugation was required, making it a simplified and effective extraction and purification procedure. The method was sensitive, rapid, simple and reliable. It effectively improved the detection efficiency during the rapid screening of pesticides in dendrobium and presented a strong practical application value. In addition, the developed method could further expand the types of target pesticides and could be used to detect more pesticide residues in foods and Chinese herbal medicine. The established Sin-QuEChERS Nano method was used for the analysis of authentic samples. The applicability of the method was evaluated by analyzing a total of 80 samples collected from Anlong, Libo, Dushan, and Yanhe County in Guizhou Province. The types of samples included dendrobium maple, Dendrobium nobile (flowers, stems, leaves) and Dendrobium officinale (flowers, stems, leaves, powder, tablets). At least one pesticide residue was detected in 12 samples, with a detection rate of 15%. The five pesticides with higher detection rates and residues were chlorpyrifos (0.08-0.5 mg/kg), chlorothalonil (0.06-3.2 mg/kg), propanil zinc (0.03-0.15 mg/kg), methyl parathion (0.04-0.23 mg/kg) and cyhalothrin (0.10-2.68 mg/kg). Except for the pesticides in maximum residue limits (MRLs), the pesticide residues detected from dendrobium samples were below the limits set by Chinese national standard (GB 2763-2021) and local standard DBS 52/048-2020.

[Simultaneous determination of six haloacetonitriles in finished water for drinking by purge and trap-gas chromatography-triple quadrupole mass spectrometry].

Haloacetonitriles (HANs) are widely used in finished water as unregulated disinfection by-products. HANs may pose much threat to human health, and there is no relevant standard examination method for these compounds. A method was established for the simultaneous determination of six HANs (chloroacetonitrile (CAN), dichloroacetonitrile (DCAN), trichloroacetonitrile (TCAN), bromoacetonitrile (BAN), bromochloroacetonitrile (BCAN), and dibromoacetonitrile (DBAN)) in finished water by using purge and trap-gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS). The purge and trap technology helps realize automatic determination of samples after collection, without using any harmful reagent. The cost and analytical efficiency of this method were superior to those of solid phase microextraction (SPME). Considering the instability of HANs, the analysis must be carried out as soon as possible after sampling, in order to avoid significant changes in their concentration during storage. In particular, the use of an appropriate quenching agent was critical to sample collection. In this study, ascorbic acid was chosen as the quenching agent. The stabilities of the spiked samples at the levels of 0.1 (TCAN), 0.2 (CAN), 1.0 (DCAN), 1.0 (BAN), 1.0 (BCAN), 4.0 (DBAN) µg/L were tested. The effect of sample storage time (0, 0.5, 1, 2, 3, 4, and 6 h) on the responses of the target component was evaluated. The stability results showed that within 6 h, the relative standard deviations of the responses for the six HANs ranged from 2.32% to 6.98%. To validate the method, first, different traps, viz. 7# (Tenax), 10# (Teanx/silica gel/cms), 11# (VOCARB), and 12# (BTEXTRAP) were optimized. Second, various chromatographic columns (VF-5, Rxi-624, DB-VRX, and HP-INNOWAX) were compared to investigate their influence on the peak shape. Under the optimal detection conditions, the six HANs in finished water were extracted with the 10# trap. The volume of the water sample was used 25 mL, with purging at 35 ℃ for 11 min, and desorbed at 190 ℃ for 1 min. Chromatographic separation was performed on a Rxi-624Sil MS chromatographic column (60 m×0.25 mm×1.40 µm). Gas chromatographic conditions were obtained under the following conditions: split ratio, 1∶10; linear velocity, 30 cm/s. The triple quadrupole mass spectrometer was operated in the electron impact (EI) mode. The target compounds were detected in the multiple reaction monitoring (MRM) mode. Quantitation was carried out using the external standard method. The results showed that the matrix effects of the six HANs ranged from 0.85 to 1.09. Good linearities were obtained in the range of the standard curves. The correlation coefficients (r) were greater than 0.9991. The limits of detection (LODs, S/N=3) were 0.8-120.0 ng/L. The limits of quantification (LOQs, S/N=10) were 1.5-300.0 ng/L. The average recoveries of the six HANs ranged from 84.2% to 106%, and the RSDs were in the range of 1.81%-10.7%. In August 2020, 38 samples of finished water were tested. All of the six HANs were found in the finished water. The concentrations of the HANs were in the range of 0.0101-1.28 µg/L, and the total detection rate was 92.1%. The detection rates of the individual components followed the order DCAN>BCAN>CAN>TCAN>BAN>DBAN. The developed method is efficient, sensitive, and environmentally friendly. It provides a high-quality technical choice for monitoring and health risk assessment of the emerging disinfection by-products of HANs.

Sugaring-out induced homogeneous liquid-liquid microextraction as an alternative mode for biological sample preparation: A comparative study.

Miniaturization of liquid-liquid extraction is a growing field of sample preparation to reduce solvent consumption, protect the environment, and preserve operators' health. In this work, four different modes of liquid-liquid microextraction have been compared including dispersive liquid-liquid microextraction, binary and ternary salting-out, and sugaring-out induced liquid-liquid microextraction. The extraction efficiency was evaluated by the enrichment factors of 14 different drugs from three pharmacological classes. Compared with the other modes, sugaring-out induced liquid-liquid microextraction was found to be the most efficient and, thus, it was applied for sample preparation of the antivirals in human plasma. Method optimization was performed using response surface methodology for the sugar type and amount (in mg), the sample pH, the equilibration time (in min), and the extractant volume (in µL). The method was then validated and found linear in the concentration range of 0.10-10 µg/mL for daclatasvir, 0.05-10 µg/mL for velpatasvir, and 0.20-10 µg/mL for ledipasvir, with correlation coefficients in the range 0.996-0.999. These results shows that sugaring-out induced liquid-liquid microextraction could be a more efficient microextraction mode for preparation of biological samples. Compared with other types of microextraction, sugaring-out induced liquid-liquid microextraction is greener, simpler, and cost-effective, with less tendency to affect the sample pH.