Determination of highly polar anionic pesticides in beehive products by hydrophilic interaction liquid chromatography coupled to mass spectrometry.

The analysis of highly polar pesticides is challenging due to their unique physicochemical properties, requiring specialized chromatographic techniques for their accurate and sensitive detection. Furthermore, the high level of co-extracted polar matrix components that can co-elute with the analytes can interfere with the analysis. Consequently, there is lack of pesticide monitoring data, as the European Food Safety Authority has pointed out. This article explores the overcoming of such difficulties in the analysis of these compounds. Analytical methodologies for the extraction, clean-up, and direct determination of 11 highly polar anionic pesticides, including glyphosate, glufosinate, ethephon, fosetyl-aluminium, and their related metabolites in complex food matrices such as honey and pollen by hydrophilic interaction liquid chromatography coupled to tandem mass spectrometry were successfully developed and validated. Solid-phase extraction and micro-solid-phase extraction employing strong anion exchange (SAX) cartridges were implemented for clean-up. The automation and miniaturization of SAX clean-up for these compounds were achieved for the first time. For method validation, SANTE/11312/2021 guideline was followed. Recoveries were between 70 and 120%, with RSDs below 20%. Limits of quantitation ranged from 0.005 to 0.020 mg kg-1. Linearity was evaluated from 0.002 to 0.200 mg kg-1. Matrix effects were assessed, showing medium to low signal suppression for most compounds. AMPA and glufosinate presented the highest signal suppression, but it was reduced after SAX clean-up. Analysis of real honey and pollen samples revealed the occurrence of the studied compounds in beehive products and showed the applicability of the validated methodologies for routine control of these complex samples.

Overview of Liquid Sample Preparation Techniques for Analysis, Using Metal-Organic Frameworks as Sorbents.

The preparation of samples for instrumental analysis is the most essential and time-consuming stage of the entire analytical process; it also has the greatest impact on the analysis results. Concentrating the sample, changing its matrix, and removing interferents are often necessary. Techniques for preparing samples for analysis are constantly being developed and modified to meet new challenges, facilitate work, and enable the determination of analytes in the most comprehensive concentration range possible. This paper focuses on using metal-organic frameworks (MOFs) as sorbents in the most popular techniques for preparing liquid samples for analysis, based on liquid-solid extraction. An increase in interest in MOFs-type materials has been observed for about 20 years, mainly due to their sorption properties, resulting, among others, from the high specific surface area, tunable pore size, and the theoretically wide possibility of their modification. This paper presents certain advantages and disadvantages of the most popular sample preparation techniques based on liquid-solid extraction, the newest trends in the application of MOFs as sorbents in those techniques, and, most importantly, presents the reader with a summary, which a specific technique and MOF for the desired application. To make a tailor-made and well-informed choice as to the extraction technique.

Immunoaffinity extraction followed by enzymatic digestion for the isolation and identification of proteins employing automated µSPE reactors and mass spectrometry.

This work describes a novel automated and rapid method for bottom-up proteomics combining protein isolation with a micro-immobilised enzyme reactor (IMER). Crosslinking chemistry based on 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) coupling was exploited to immobilise trypsin and antibodies onto customisable silica particles coated with carboxymethylated dextran (CMD). This novel silica-CMD solid-phase extraction material was characterised using Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), conductometric titrations and enzymatic colorimetric assays. Micro-solid-phase extraction (µSPE) cartridges equipped with the modified CMD material were employed and integrated into an automated and repeatable workflow using a sample preparation workstation to achieve rapid and repeatable protein isolation and pre-concentration, followed by tryptic digestion producing peptide fragments that were identified by liquid chromatography mass spectrometry (LC-MS).

Pesticide residue analysis in different spice samples by automatic µSPE clean-up workflow determination using LC-MS/MS.

Spices such as paprika, curry, turmeric, dry chilli, and black pepper are grown in various geographic locations and widely used by consumers across the world. Pesticides applied during crop production practices could contaminate the produce, affecting the quality and posing a health risk for consumers. The complexity of the spice matrix and the wide range of target pesticides potentially present require special sample extraction and clean-up treatments to overcome matrix interference and ion suppression. In this study, sample extracts from spice matrices (paprika/curry/turmeric/dry chilli/black pepper) were cleaned up by an automated µSPE clean-up method for multi-residue analysis of pesticides using LC-MS/MS. The automated µSPE clean-up method involves pre-filled cartridges containing various sorbent materials suitable for numerous co-extractives and the automated clean-up process was carried out using an autosampler. The regulatory limit for pesticides in spices varies with type, with a low MRL of 0.05 mg kg-1 or higher for 99% of the analytes. At spiking concentrations of 0.05 and 0.1 mg kg-1, good recoveries between 70 and 120% with RSD values below 20% were achieved for more than 98% of the compounds. With automatic clean-up of samples that takes 5 min/sample, 20% increased output per day shows an important advantage achieved compared to manual clean-up.

Coupling of micro-solid-phase extraction and internal extractive electrospray ionization mass spectrometry for ultra-sensitive detection of 1-hydroxypyrene and papaverine in human urine samples.

Quantification of ultra-trace analytes in complex biological samples using micro-solid-phase extraction followed by direct detection with internal extractive electrospray ionization mass spectrometry (µSPE-iEESI-MS) was demonstrated. 1-Hydroxypyrene (1-OHP) and papaverine at attomole levels in human raw urine samples were analyzed under negative and positive ion detection mode, respectively. The µSPE was simply prepared by packing a disposable syringe filter with octadecyl carbon chain (C18)-bonded micro silica particles, which were then treated as the "bulk sample" after the analytes were efficiently enriched by the C18 particles. Under the optimized experimental conditions, the analytes were readily eluted by isopropanol/water (80/20, V/V) at a high voltage of ± 4.0 kV, producing analyte ions under ambient conditions. The limit of detection (LOD) was 0.02 pg/L (9.2 amol) for 1-hydroxypyrene and 0.02 pg/L (5.9 amol) for papaverine. The acceptable linearity (R2 > 0.99), signal stability (RSD ≤ 10.7%), spike recoveries (91-95%), and comparable results for real urine samples were also achieved, opening up possibilities for quantitative analysis of trace compounds (at attomole levels) in complex bio-samples. Graphical abstract.

Dummy-surface molecularly imprinted polymers as a sorbent of micro-solid-phase extraction combined with dispersive liquid-liquid microextraction for determination of five 2-phenylpropionic acid NSAIDs in aquatic environmental samples.

A highly binding dummy template surface of molecularly imprinted polymers (MWNTs-MIPs) was synthesized on multi-walled carbon nanotubes surface using 2-phenylpropionic acid as dummy template, 4-vinylpyridine as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, and DMF as porogen by precipitation polymerization method. MIPs were characterized by FT-IR spectroscopy, scanning electron microscope, thermo-gravimetric analysis, and nitrogen adsorption-desorption experiment. Adsorption and selectivity experiments of MIPs and non-imprinted polymers (NIPs) verified that the MIPs had a good selectivity and adsorption properties for five 2-phenylpropionic acid nonsteroidal anti-inflammatory drugs (NSAIDs). Imprinted polymer was used as a sorbent material for µSPE in current work and µSPE-DLLME method was selected for pretreatment of water samples. The µSPE-DLLME method was successfully used for the pre-concentration of five non-steroidal anti-inflammatory drugs in different environmental water samples prior to ultra-high performance liquid chromatography-tandem mass spectrometry. Efficiencies of µSPE and DLLME were thoroughly investigated and optimized in this study. The optimal results were obtained by using 3 mL of 1% formic acid-acetonitrile as elution solvent and dichloroethane and acetonitrile as extractant and disperser solvent, respectively. Limits of detection and quantification of five NSAIDs for different water matrices varied from 0.50 to 1.10 ng L-1 and 0.93 to 2.20 ng L-1, respectively. Each target analyte had a good linearity in its corresponding concentration range. Enrichment factors of target analytes ranged from 91 to 215. Recoveries of the target analytes were between 72.43 and 113.99% at the concentration levels of 0.02, 0.1, and 0.5 µg L-1. The developed method was successfully applied to extraction and analysis of NSAIDs in different water samples with satisfactory results which could help us better understand their environmental fate and risk to ecological health. Graphical abstract Dummy-surface molecularly imprinted polymers as a sorbent of micro-solid-phase extraction combined with dispersive liquid-liquid microextraction for determination of five 2-phenylpropionic acid NSAIDs in aquatic environmental samples.

Green application of surfactant modified silica as effective sorbent for extraction and preconcentration of sulfonamide residues in environmental water and honey samples.

Micro-solid phase extraction (µ-SPE) using surfactant coated silica for extraction and preconcentration of sulfonamide residues at trace levels in environmental water and honey samples prior their analysis by high performance liquid chronatography coupled with photodiode array detector (HPLC-PDA). The sample solution were dispersed in a small amounts of solid sorbent by vacuum manifold for sample preparation, and extraction occurred by adsorption in a short time. Finally, the analytes were subsequently desorbed using an appropriate solvent. The pure and coated silica were physicochemically and morphologically characterized by nittrogen (N2) sorptions analyses, and transmission electron microscopy (TEM). Parameters influencing extraction efficiency, such as amount of sorbent, kind, concentration and volume of surfactant, and kind and volume of desorption solvent, were investigated. The optimum conditions of the proposed method, were mixed standard/sample solution (10 mL), 0.4 g silica, 0.03 M CTAB (150 µL), and 500 µL methanol (as elution solvent). The proposed method, under optimal conditions, showed excellent linearity in different ranges (9-300 µg L-1, the a coefficient of determination (R2) of greater than 0.99), good repeatability (RSD < 6.72 %), good sensitivity (LODs in the range of 1 to 3 µg L-1), high enrichment factor (5.63-13.33), and acceptable relative recoveries (61.0-121.4 %). The developed µ-SPE method was applied to analyze sulfonamide residues in water and honey samples with relative recoveries of 60.9-119.4 % were obtained. This alternative method is simple and is also environmentally friendly which assessed using Analytical Eco-scale and Analytical GREEnness metric (AGREE).

Development of the Pipette-Tip Micro-Solid-Phase Extraction for Extraction of Rutin From Moringa oleifera Lam. Using Activated Hollow Carbon Nanospheres as Sorbents.

Herein, a micro-solid-phase extraction (µSPE) method was developed using a pipette tip for rutin extraction, employing activated hollow carbon nanospheres (HCNSs) as the sorbent. Characterization of the activated carbon nanospheres through TGA, FTIR, and SEM analysis confirmed the success of the activation process. The study demonstrated the efficacy of PT-µSPE in rutin extraction under pH 2 conditions with a standard concentration of 2 mg·L-1. The optimal mass of HCNSs was found to be 2 mg, and a loading volume of 500 µL resulted in the maximum recovery of rutin. Propan-2-ol was the best elution solvent with 15 aspirating/dispensing cycles. The correlation of determination (R 2) for the calibration curve was found to be 0.9991, and the LOD and LOQ values were 0.604 and 1.830 mg·L-1, respectively. The applicability of the method was demonstrated by extracting rutin from a complex Moringa oleifera leaf extract with the relative standard deviation (RSD) of 3.26%, thereby validating this method as feasible for the extraction of useful bioactive compounds from complex plant samples.

NiFe-LDH/nylon 6 composite electrospun on polypropylene membrane: A new extractive device development for porous membrane protected micro-solid-phase extraction of organophosphate pesticides from fresh fruit juice samples coupled with liquid chromatography tandem mass analysis.

A unique strategy for developing porous membrane protected micro-solid phase extraction has been provided. An electrospun composite was fabricated on the sheet of membrane. To this end, NiFe-layered double hydroxide/Nylon 6 composite nanofibers were coated on a polypropylene membrane sheet followed by folding into a pocket shape, which were then utilized as a novel extractive device to extract of organophosphorus pesticides from fresh fruit juice samples prior to liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The fabricated hybrid composites were successfully characterized. The effective parameters on extraction performance were investigated. LODs were 0.020-0.065 ng mL-1. Excellent linearity (R2≥0.996) was observed between 0.05 and 100.0 ng mL-1. RSDs% were in the range of 3.1-5.8% (intra-day, n = 3) and 2.6-5.5% (inter-day, n = 3×3). Satisfactory related recovery values within the acceptable range of 90.7-111.2% with RSDs% below 6.7% were achieved for the analysis of real samples.

LC-MS/MS Analysis of AEA and 2-AG.

LC-MS/MS is a powerful analytical technique that provides unequivocal identification and reliable quantification of the analytes, using Selected Reaction Monitoring or Multi Reaction Monitoring acquisition mode.Anandamide (N-arachidonoylethanolamine, AEA) and 2-Arachidonoylglycerol (2-AG) are the most abundant endocannabinoids (eCBs), which play a major role in a wide variety of physiological and pathological processes. Analysis of those compounds by means of LC-MS/MS allows the detection of very low concentrations in biological samples. Here, we describe how to determine AEA and 2-AG levels in tiny samples of tissues and plasma through LC-MS/MS, by using very quick and easy-to-perform extraction procedures, with reduced solvent consumption.

Determination of endocannabinoids and their conjugated congeners in the brain by means of µSPE combined with UHPLC-MS/MS.

The present study encompasses the development of a fast and reliable analytical method to quantify the main endocannabinoids and some of their conjugated congeners, particularly N-arachidonoyl amino acids, in brain tissue. Samples were homogenized and a micro solid phase extraction (µSPE) procedure was developed for brain homogenate clean-up. Miniaturized SPE was selected as it allowed to work with reduced sample amounts, while maintaining high sensitivity; this last feature was mandatory due to the low concentration of endocannabinoids in biological matrices that makes their determination a challenging analytical task. UHPLC-MS/MS was used for the analysis as it provided a great sensitivity, especially for conjugated forms that were detected by negative ionization. Polarity switching was applied during the run; low limits of quantification were between 0.003 ng g-1 and 0.5 ng g-1. This method provided also low matrix effect (lower than 30%) and good extraction recoveries in the brain. To the best of our knowledge, this is the first time that µSPE is applied on this matrix for this class of compounds. The method was validated according to international guidelines, and then tested on real cerebellum samples from mice, which were sub-chronically treated with URB597, a well-known inhibitor of the fatty acid amide hydrolase.

Determination of urinary metabolites of cannabidiol, Δ8-tetrahydrocannabinol, and Δ9-tetrahydrocannabinol by automated online µSPE-LC-MS/MS method.

In this study, an automated online micro-solid-phase extraction (µSPE)-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for the detection of metabolites of cannabidiol (CBD), Δ8-tetrahydrocannabinol (Δ8-THC), and Δ9-tetrahydrocannabinol (Δ9-THC), particularly 7-carboxy- cannabidiol (7-COOH-CBD), 11-nor-9-carboxy-Δ8-tetrahydrocannabinol (Δ8-THCCOOH), 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (Δ9-THCCOOH), and 11-nor-9-carboxy-Δ9- tetrahydrocannabinol-glucuronide (Δ9-THCCOOH-glu) in urine. An instrument top sample preparation (ITSP) cartridge was introduced to increase the sensitivity toward analytes and decrease the matrix effect of the urine. LC-MS/MS analysis was performed in the multiple-reaction monitoring mode, and the analytes were separated using an Acquity UPLC HSS T3 (2.1 × 100 mm, 1.8 µm) column and gradient elution with water containing 0.05 % acetic acid and methanol as the mobile phase. The calibration range was 0.5-200 ng/mL for all the analytes, with a correlation coefficient (r) of ≥0.996 and a weighting factor of 1/x2. The limits of detection for 7-COOH-CBD, Δ8-THCCOOH, Δ9-THCCOOH, and Δ9-THCCOOH-glu were 0.06, 0.02, 0.03, and 0.1 ng/mL, respectively. The intra- and inter-day accuracy ranged from -8.0 to 6.2 % and -7.3 to 7.8 % with a precision of ≤7.2 % and ≤6.2 %, respectively. The method was also validated for selectivity, recovery, matrix effect, stability, and dilution integrity. The developed method was successfully applied to the analysis of 78 urine samples, and 7-COOH-CBD, Δ8-THCCOOH, Δ9-THCCOOH, and Δ9-THCCOOH-glu were detected in 54 urine samples at normalized concentrations of 1.1, 0.6-939.1, 0.9-2595.0, and 1.3-527.6 ng/mg creatinine, respectively.

Validation of the QuEChERSER mega-method for the analysis of pesticides, veterinary drugs, and environmental contaminants in tilapia (Oreochromis Niloticus).

Diverse food safety programmes around the world are designed to help ensure production of safe food. To meet this need, the development and implementation of more efficient and effective analytical methods to monitor residues (pesticides and veterinary drugs) and contaminants in food is important. In this study, we report the validation results for a simple high-throughput mega-method for residual analysis of 213 pesticides and veterinary drugs, including 15 metabolites, plus 12 environmental contaminants (polychlorinated biphenyls) in tilapia muscle for implementation in routine laboratory analyses. The generic sample preparation method and analytical approach are known as QuEChERSER (more than QuEChERS). A small portion of the initial extract (204 µL) is taken for analysis by ultrahigh-performance liquid chromatography (UHPLC) tandem mass spectrometry (MS/MS) covering 145 analytes, and the remaining extract undergoes a salting out step followed by an automated robotic instrument top sample preparation (ITSP) cleanup, also known as micro-solid-phase extraction (µSPE), plus fast low-pressure gas chromatography LPGC-MS/MS for 134 analytes (66 pesticides are targeted in both UHPLC-MS/MS and LPGC-MS/MS). The mega-method was validated in spiked tilapia samples at 5, 10, 15, and 20 ng/g with 10 replicates per level over two days (n = 80 overall), and 70-140% recoveries with RSDs ≤20% were achieved for 92% of the analytes in LC and 82% in GC. No significant matrix effects were observed for the analytes in LPGC-MS/MS, and only 5% of the analytes exceeded ±20% matrix effect in UHPLC-MS/MS. Analysis of standard reference materials (NIST SRMs 1946 and 1947) for contaminants in freeze-dried fish showed acceptable results, further demonstrating that the QuEChERSER mega-method can be implemented to expand analytical scope and increase laboratory efficiency compared to the QuEChERS method.

Evaluation of a septumless mini-cartridge for automated solid-phase extraction cleanup in gas chromatographic analysis of >250 pesticides and environmental contaminants in fatty and nonfatty foods.

The QuEChERSER mega-method has recently been introduced to quantify and identify a wide range of chemical residues (pesticides, veterinary drugs, environmental contaminants, among others) in nearly all types of foods. The approach calls for taking a small amount of the initial extract to cover analytes amenable to liquid chromatography, and the remainder is salted out for analysis by gas chromatography (GC), both with mass spectrometry (MS) based detection. In the case of GC-MS(/MS), the extract undergoes automated robotic mini-cartridge solid-phase extraction (SPE) cleanup in a technique known as µSPE or instrument-top sample preparation (ITSP). In 2022, a septumless mini-cartridge for µSPE was introduced to improve upon the ITSP design. The new design houses a bed of 20 mg anhydrous MgSO4, 12 mg each of C18 and primary secondary amine sorbents, and 1 mg of graphitized carbon black, the latter substituting for CarbonX used in the ITSP product. The septumless µSPE mini-cartridge employs a different gripping mechanism with the syringe needle that allows leak-free operation at higher flow rates (e.g. 10 µL/s), whereas the ITSP design is limited to 2 µL/s. Based on cleanup and analyte elution profiles, the extract load volume and flow rate was increased in µSPE for QuEChERSER from 300 µL at 2 µL/s to 500 µL at 5 µL/s, which improved accuracy of results, sped the cleanup step, and obviated the need for micro-vial inserts in the receiving vials. The new design also reduced both the amount and consistency of dead (void) volumes in the mini-cartridges from 83 ± 14 µL to 52 ± 7 µL for 200-600 µL load volumes. Normalization of peak areas to internal standards led to recoveries between 80 and 120% with typical RSDs <5% in low-pressure GC-MS/MS of 227-242 out of 252 pesticides, polychlorinated biphenyls, polybrominated diphenyl ethers, and polycyclic aromatic hydrocarbons in hemp powder, spinach, whole milk, egg, avocado, and lamb meat.

Dispersive micro solid phase extraction based ionic liquid functionalized ZnO nanoflowers couple with chromatographic methods for rapid determination of aflatoxins in wheat and peanut samples.

Aflatoxins (AFs) contaminate agricultural products in a wide range of ways during their harvesting, storage and transport. Therefore, the detection of AFs has certain practical significance. Herein, a dispersive micro solid phase extraction (D-µSPE) technology was constructed based on 1-hexyl-3-methylimidazolium hexafluorophosphate ([HMIM][PF6]) fabricated ZnO nanoflowers for AFs extraction from food matrix before HPLC procedure. The key parameters affecting the extraction efficiency were studied. Under optimal experimental conditions, the method showed excellent linearity with high correlation coefficients (≥0.994). LOD and LOQ were 0.034 and 0.114 µg/kg for AFB1, 0.024 and 0.082 µg/kg for AFB2, 0.067 and 0.226 µg/kg for AFG1 and 0.025 and 0.084 µg/kg for AFG2. The recovery of actual samples spiked with analytes (at 5, 15 and 20 µg/kg) were from 93.8 to 105.1%. Overall, an accurate AFs analysis method was developed and could be applied to the determination of AFs in various food and agricultural products.

Evaluation of the automated micro-solid phase extraction clean-up system for the analysis of pesticide residues in cereals by gas chromatography-Orbitrap mass spectrometry.

Food analysis is a tremendously broad field that is constantly evolving. New methods have emerged to increase productivity, such as modern miniaturized and robotic analytical techniques. In this paper, a micro-solid-phase extraction system (µ-SPE) for clean-up was combined with a robotic autosampler to yield ready-to-analyze extracts. The system was evaluated for its applicability in routine laboratories. The new, automated, high-throughput µ-SPE clean-up method was applied to acetonitrile extracts and was developed for the analysis of pesticide residues in cereals by gas chromatography-Orbitrap mass spectrometry (GC-Orbitrap-MS). The µ-SPE clean-up efficiency was demonstrated in the removal of matrix-interfering components and in the recovery of pesticides. The sorbent bed mixture consisted of magnesium sulfate, primary-secondary amine, C18, and CarbonX, and effectively retained matrix components without loss of target analytes. Analysis of five types of cereals (barley, oat, rice, rye, and wheat) by GC-Orbitrap-MS showed that the method removed more than 70% of matrix components. The clean-up method was validated for 170 pesticides in rye, 159 pesticides in wheat, 142 pesticides in barley, 130 pesticides in oat, and 127 pesticides in rice. Spike recovery values were 70-120% for all pesticides and the repeatability, calculated as the relative standard deviation, was less than 20%. The limits of quantitation achieved were 0.005 mg kg-1 for almost all analytes, ensuring compliance with the maximum residue limits.

Development of a magnetic MOF-based M-D-µSPE methodology combined with LC-MS/MS for the determination of fluorotelomer alcohols and its metabolites in animal derived foods.

In this study, a novel modified metal organic framework (MOF) was prepared and used as adsorbent of miniaturized solid-phase extraction (M-D-µSPE) for analyzing 8-2 FTOH and its metabolites in edible tissues by LC-MS/MS. This synthesized adsorbent, named as Fe3O4@Fe-MIL 101-NH2 (magnetic Fe-MOF), was characterized. Moreover, the effects factors on the adsorption behavior of the adsorbents for the analytes were investigated and optimized in detail, such as solution pH, adsorbent amount, extraction time, desorption condition. The adsorbtion mechanism of magnetic Fe-MOF might be electrostatic interaction, CF-π hydrophobic and Lewis acid base. Compared with conventional adsorbents (such as PSA, C18), magnetic Fe-MOF reduced matrix effect. The limits of quantification ranged 0.10-1.5 µg/kg. The recoveries of analytes ranged 78.0% - 90.3% in spiked samples, with relative standard deviations less than 12.0%. The developed method was successfully utilized to analyze incurred samples, which proves that it is a rapid, efficient, and sensitive method.

Pipette-tip micro-solid phase extraction based on melamine-foam@polydopamine followed by ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry for detection of psychotropic drugs in human serum.

In this work, pipette-tip micro-solid phase extraction (PT-µSPE) which packed by melamine-foam@polydopamine (MF@PDA) coupled with ultra-high-performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF) was developed for extraction and determination of psychotropic drugs in serum samples. Considering the operation back pressure, the melamine-foam as carrier material with 3D cross-linked grid structure can provide high permeability and contact surface. MF@PDA was prepared by self-polymerization reaction of dopamine under weak alkaline conditions and characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS). The surface group of PDA containing catechol structure, quinone structure and amine group has multi-interaction with psychotropic drugs which can increase the adsorption capacity. Moreover, the parameters affecting extraction efficiencies such as extraction and desorption cycle, pH value, eluent type, ionic strength and amount of sorbent were investigated. Based on the high sensitivity and accuracy mass measurement by TOF/MS, under the optimized extraction condition, the limits of detection (LOD) of this method were obtained in the range of 0.002-0.1 ng ml-1. The linearity was ranged from 0.01 ng ml-1 to 600 ng ml-1, and all the correlation coefficients (R2) were above 0.993. The spiked recoveries were in the range of 80.04% to 109.18% in real sample test and RSD values obtained from 0.95% to 9.85%. The results demonstrate that MF@PDA-PT-µSPE-UHPLC-QTOF is a sample and reliable method for the detection of psychotropic drugs in serum sample.

Quantitative analysis of oxysterols in zebrafish embryos by HPLC-MS/MS.

Zebrafish is an in vivo model used in toxicology to estimate the effects of xenobiotics and their teratogenic consequences. The knowledge of the oxysterols profile in zebrafish, during early embryonic stages, provides important information on the role and biological function of these molecules. This work reports the development and validation of a LC-MS/MS method for the determination of 7 different oxysterols in zebrafish embryos. Sample was treated with a combination of liquid/liquid extraction (LLE) followed by micro solid phase extraction (µSPE) clean-up in order to remove matrix interference and obtain a suitable enrichment factor of the analytes. The method was validated on 2 different embryos growing stages, 3-4 and 24 h post fertilization (hpf), as slight differences in terms of recovery and matrix effect were shown. The validation results provided good accuracy (bias ≤17%; 20% at LOQ) and repeatability (≤15%; ≤19% at LOQ), with low LOQs in the range 22 and 65 pg on 100 embryos sample, without any analyte derivatization, demonstrating the suitability of this analytical method as a useful tool to understand the correlation between oxysterols profile and developmental abnormalities induced by xenobiotic exposure.

Synthesis and application of magnetic-surfaced pseudo molecularly imprinted polymers for zearalenone pretreatment in cereal samples.

Zearalenone (ZEA) is a fungal contaminant widely found in grains. In cereal samples, trace zearalenone was extracted and enriched using magnetic-surfaced pseudo molecularly imprinted polymers (SPMIPs) and detected. SPMIPs were prepared with Fe3O4 as the magnetic core, modified halloysites nanotubes as supporting materials, and selective imprinted polymers as shells. Vinyl was modified on the surface of halloysites nanotube. SPMIPs were synthesized with pseudo templates. SPMIPs as the adsorbent of dispersed-solid phase extraction (µ-SPE) were used to purify and enrich ZEA from maize samples. After optimized, the pretreatment method was evaluated. The linearity of the method was ranged within 10-200 ng mL-1. LOD and LOQ were 2.5 ng mL-1 and 8 ng mL-1 respectively. The ZEA spiking recoveries in maize samples ranged within 74.95-88.41% were with good RSDs lower than 4.25%. The developed method was successful applied in maize, oat, and wheat sample treatments and compared.