Complex Matrix Interference Research Articles

Nanostructured electrochemical platform for sensitive detection of melatonin in human serum and tablets

Melatonin (MT) is a crucial hormone for biological rhythms that influences sleep-wake cycles. The therapeutic value of MT in neurological disorders highlights the need for precise detection. However, challenges like low concentrations in biological samples and complex matrix interferences persist, necessitating rapid and precise analytical techniques. This study presents the novelty of designing a novel sensor that combines a molecularly imprinted polymer with polytoluidine blue O (PTBO) and multi-walled carbon nanotubes on a glassy carbon electrode for MT detection and the study of the interaction between MT and the proposed sensor using density functional theory (DFT). DFT showed that MT has a high nucleophilic character and low electrophilicity compared to TBO, which is a strong electrophile. This supports electron transfer from MT to TBO/PTBO, as indicated by the electronic chemical potentials and molecular electrostatic potentials. Scanning electron microscopy was used to see the morphology. Electrochemical measurements using differential pulse voltammetry demonstrated enhanced sensitivity and selectivity. Under optimized conditions, the sensor exhibited a linear response ranging from 1 to 1000 µM with a limit of detection and limit of quantification of 0.027 µM and 0.092 µM respectively. The performance of the sensor was evaluated in pharmaceutical tablets and human serum. Validation experiments confirmed the reliability of the sensor, with recovery rates of 97.5 % for serum and 98.0 % for pharmaceutical tablets, alongside low relative standard deviations indicating good precision. Interference studies showed minimal effects from coexisting substances, highlighting the selectivity of the proposed sensor. Comparative analysis with existing sensors showed superior performance.

Synergy of Target-Induced Magnetic Network and Single-Drop Chromogenic System for Ultrasensitive "All-in-Tube" Detection of miRNA in Whole Blood.

The development of liquid biopsy methods for the accurate and reliable detection of miRNAs in whole blood is critical for the early diagnosis and monitoring of diseases. However, accurate quantification of miRNA expression levels remains challenging due to the complex matrix and low abundance of miRNAs in blood samples. Herein, we report a contactless signal output strategy with low background interference that ensures "zero-contact" between the reaction system and the colorimetry system. The designed target-induced magnetic ZnS/ZIF-90/ZnS network can serve as a unique signal amplifier and transducer. It releases hydrogen sulfide (H2S) gas in an acidic solution which can be concentrated in a droplet of only a few microliters in volume, etching the silver layer of Au@Ag nanostars (NSTs) in the droplet. This will lead to changes in the localized surface plasmon resonance signals of the NSTs. Finally, quantitative detection of let-7a is realized by measuring the offset value of the UV-vis absorption peak. Therefore, by virtue of the synergistic action of quadruple signal amplification methods, including catalytic hairpin assembly, ZnS/ZIF-90/ZnS, magnetic separation, and microextraction, the "All-in-Tube" ultrasensitive detection of low-abundance let-7a in whole blood is achieved with a detection limit as low as the aM level. In addition, the "zero-contact" signal output mode effectively solves the problem of complex matrix interference, demonstrating the great potential of this method for miRNA quantification in complex samples, such as whole blood.

Magnetic molecularly imprinted polymers integrated ionic liquids for targeted detecting diamide insecticides in environmental water by HPLC-UV following MSPE

Efficiently detecting diamide insecticides in environmental water is challenging due to their low concentrations and complex matrix interferences. In this study, we developed ionic liquids (ILs)-incorporated magnetic molecularly imprinted polymers (IL-MMIPs) for the detection of diamide insecticides, capitalizing on the advantages of ILs and quick magnetic separation through surface imprinting. Tetrachlorantraniliprole was used as the template, and a specific IL, 1-vinyl-3-ethylimidazolium hexafluorophosphate ([VEIm][PF6]), was employed as the functional monomer. Various synthesis conditions were investigated to optimize adsorption efficiency. The prepared IL-MMIPs were successfully employed as adsorbents in magnetic solid-phase extraction (MSPE) to selectively extract, separate, and quantify three types of diamide insecticides from water samples using HPLC-UV detection. Under optimal conditions, the analytical method achieved low limits of detection (0.69 ng mL−1, 0.64 ng mL−1, 0.59 ng mL−1 for cyantraniliprole, chlorantraniliprole and tetrachlorantraniliprole, respectively). The method also displayed a wide linear range (0.003–10 μg mL−1 for cyantraniliprole and chlorantraniliprole, and 0.004–10 μg mL−1 for tetrachlorantraniliprole, respectively) with satisfactory coefficients (R2≥0.9996), and low relative standard deviation (RSD≤2.55%). Additionally, extraction recoveries fell within the range of 79.4%–109%. The results clearly demonstrate that IL-MMIPs exhibit exceptional recognition and rebinding capabilities. The developed IL-MMIPs-MSPE-HPLC-UV method is straightforward and rapid, making it suitable for the detection and analysis of three kinds of diamide insecticides in environmental water.

Development of a portable gas chromatography linear ion trap mass spectrometer (GC-LIT-MS) for VOCs analysis in water

The detection of volatile organic compounds (VOCs) in water faces challenges due to the presence of complex matrix interferences and low concentration. This paper presented a portable gas chromatography linear ion trap mass spectrometer (GC-LIT-MS) coupled with dynamic headspace sampling (DHS) system for sensitive and rapid on-site analysis of VOCs in water. The instrument weighs 18 kg and has compact dimensions of 43 cm × 35 cm x 20 cm, offering portability and convenience. A low thermal mass (LTM) chromatographic column, utilizing resistive heating, enables rapid heating and cooling within the runtime of GC. The linear ion trap, for the first time, has been integrated as a mass analyser in portable gas chromatography-mass spectrometer (GC-MS). Its ability to store a greater number of ions within the trap expands the dynamic range of the instrument. The influence of dynamic headspace injection conditions on the purging efficiency of VOCs was investigated and the equilibrium temperature was optimized. The GC-LIT-MS method was demonstrated to be capable to identify and separate 55 VOCs in water within 4 min, with most of them exhibiting detection limits of less than 1 μg L−1. The calibration of 4 VOCs with concentrations ranged from 2 parts per million (ppm) to 200 ppm showed excellent linearity (R2 > 0.99) and dynamic range more than five orders of magnitude. Resolution superior to unit mass was achieved within the range of 15 AMU to 550 AMU.

Optimization of a ultra-high-pressure liquid chromatography-tandem multiple reaction monitoring mass spectrometry method for monitoring haloacetic acids as chlorinated disinfection by-products in the fresh-cut industry

Haloacetic acids (HAAs) are one of the most important chlorinated disinfection by-products generated during water disinfection in the fresh-cut industry, and they can remain in the product, resulting in a consumer health risk. In this study, ultra-high-pressure liquid chromatography-tandem multiple reaction monitoring mass spectrometry (UHPLC-MRM) analysis used for drinking water was optimized and applied for the quantification of nine HAAs (HAA9) in fresh-cut lettuce and process water samples, with the complex matrix interferences for separation, and quantification problems. The method showed good selectivity, specificity and linearity, satisfactory values for trueness (recoveries of 80–116 %), precision (<22 %), and uncertainty (<55 %). Quantification limits varied from 1 to 5 µg L−1 or µg kg−1. The matrix effect for tribromoacetic, bromochloroacetic and chlorodibromoacetic acid was corrected by matrix-matched calibration and standard addition. After storage at -20 °C, only monobromoacetic acid was the HAA which loss happened after 7 days. The application of the methodology in lettuce and process water samples from the industry was successfully implemented. Therefore, this method could be employed for the quality control and regulatory analysis of HAAs in fresh products and process water from the fruit and vegetable industry.

Facile synthesis of spherical covalent organic frameworks for enrichment and quantification of aryl organophosphate esters in mouse serum and tissues.

Here, an imine-linked-based spherical covalent organic framework (COF) was prepared at room temperature. The as-synthesized spherical COF served as an adsorbent in dispersive solid-phase extraction (dSPE), by its virtue of great surface area (1542.68 m2 /g), regular distribution of pore size (2.95nm), and excellent stability. Therefore, a simple and high-efficiency dispersive solid phase extraction method based on a spherical COF coupled with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was established to determine aryl organophosphate esters in biological samples. This approach displayed favorable linearity in the range of 10.0-1000.0ng/L (r>0.9989), a high signal enhancement factor (58.8-181.8 folds) with low limits of detection (0.3-3.3ng/L). Moreover, it could effectively eliminate complex matrix interference to accurately extract seven aryl organophosphate esters from mouse serum and tissue samples with spiked recoveries of 82.0%-117.4%. The as-synthesized spherical COF has been successfully applied in sample preparation. The dSPE-HPLC-MS/MS method based on a spherical COF has potential application to study the pollutants' metabolism in vivo.

A rapid magnetic-based purification of Cd2+ and Pb2+ prior to portable electrochemical determination for grain.

How to quickly separate and detect cadmium (Cd2+) and lead (Pb2+) from solid samples is a difficult problem that needs to be solved. For this, Fe3O4@agarose@iminodiacetic acid (IDA) was synthesized and used for rapid purification of Cd2+ and Pb2+. This material can remove complex matrix interference completely within a short time of 15min. The mechanism of the adsorption kinetics fit well to a pseudo-second-order model. A portable screen-printed electrodes (SPEs)-based electrochemical detection platform was established. After coupling with the pretreatment, the whole detection process only took within 30min. The limits of detection (LOD) were ten times lower than those of the Codex general standard, with values of 0.02 and 0.01mg/kg for Pb2+ and Cd2+, respectively. The recoveries ranged from 84.1% to 109.7% in naturally contaminated grain, in good agreement with the ICP-MS, demonstrating great prospects for the rapid screening and monitoring of Cd2+ and Pb2+ in grain.

Highly-Selective Analytical Strategy for 90 Pesticides and Metabolites Residues in Fish and Shrimp Samples.

The analysis of pesticide residues in aquatic products is challenging due to low residue levels and the complex matrix interference. In this study, we developed a simple, fast method for the trace analysis of 90 pesticides and metabolites in aquatic products. The analytes covered a wide polarity range with log Kow (log octanol-water partition coefficient) ranging from -1.2 to 6.37. Grass carp (Ctenopharyngodon idellus) and prawn (Penaeus chinensis) samples were chosen to validate the quantification method. The samples were extracted by 0.2% formic-acetonitrile, cleaned by solid-phase extraction (PRiME HLB), and analyzed by high performance liquid chromatography-tandem mass spectrometry. The results showed good linearities for the analytes and were observed in the range of 0.05-50 μg/L. The recoveries of the method were within 50.4-118.6%, with the relative standard deviations being lower than 20%. The limits of quantifications (LOQs) of the method were in the range of 0.05-5.0 μg/kg, which were superior to values compared with other research. The developed method was applied to detect pesticide residues in prawn samples from eastern coastal areas of China. Three herbicide residues of diuron, prometryn, and atrazine were detected in prawn samples. The method was sensitive and efficient, which is of significance in expanding the screening scope and improving the quantitative analysis efficiency in aquatic products.

An enhanced approach for targeted multi-residue screening of pesticides in complex herbal medicines by ultra high-performance liquid chromatography tandem ion mobility/quadrupole time-of-flight mass spectrometry

Recently, serious concerns have been raised about potential safety risk posed by exogenous pesticide contaminants in herbal medicines. It is highly desirable to have reliable detection and determination of suspected pesticide residues for understanding of their overall quality. However, inherent metabolites abundant in herbal medicines typically make screening of trace-level pesticide residues arduous. Taking Lonicerae Japonicae Flos (LJF) as an example, the current study investigated the capability of a three-dimensional separation system, ultra high-performance liquid chromatography tandem ion mobility/quadrupole time-of-flight mass spectrometry (UPLC-IM/Q-TOF MS), for qualitative detection of numerous pesticides when suffering from complex matrix interferences. The comparison of collision gases was first performed to improve unwanted dissociations of pesticides, particularly labile ones, and nitrogen was ultimately chosen instead of argon. Further optimization of key MS parameters resulted a data-independent high-definition MSE (HDMSE) method was developed. Then, an in-house pesticide scientific library (PSL) containing 438 pesticides was constructed following a four-step workflow. Based on multi-dimensional information in this library, different identification criteria were compared and an enhanced qualitative screening approach for 432 targeted pesticides was finally proposed and validated. By its application to 104 batches of LJFs, the approach was demonstrated effective in resolving complex matrix interferences. Moreover, collision cross section (CCS) for identification purpose was favorable to improve detection sensitivity while maintain ideal accuracy.

"Lollipop" particle counting immunoassay based on antigen-powered CRISPR-Cas12a dual signal amplification for the sensitive detection of deoxynivalenol in the environment and food samples

Deoxynivalenol is one of the most widely distributed mycotoxins in cereals and poses tremendous threats to the agricultural environment and public health. Therefore, it is particularly important to develop sensitive and interference-resistant deoxynivalenol analysis methods. Here, we establish a “Lollipop” particle counting immunoassay (LPCI) based on antigen-powered CRISPR-Cas12a dual signal amplification. LPCI achieves high sensitivity and accuracy through antigen-powered CRISPR-Cas dual signal amplification combined with particle counting immunoassay. This strategy not only broadens the applicability of the CRISPR-Cas system in the field of non-nucleic acid target detection; it also improves the sensitivity of particle counting immunoassay. The introduction of a polystyrene "lollipop" immunoassay carrier further enables efficiently simultaneous pre-treatment of multiple samples and overcomes complex matrix interference in real samples. The linear detection range of LPCI for deoxynivalenol was 0.1–500 ng/mL with a detection limit of 0.061 ng/mL. The platform greatly broadens the scope of the CRISPR-Cas sensor for the detection of non-nucleic acid hazards in the environment and food samples.

Advances in Molecular Imprinting Technology for the Extraction and Detection of Quercetin in Plants.

Quercetin is a kind of flavonoid compound, which has antioxidative, anti-aging and anti-cancer effects, so it is of great importance to study the efficient extraction and highly sensitive detection of quercetin. Molecular imprinting technology has remarkable selectivity and resistance to complex matrix interference, which is often used for extracting quercetin. The methods of molecular imprinted solid phase extraction, molecularly imprinted microsphere extraction, molecularly imprinted electrochemical sensor recognition and molecularly imprinted composite material extraction of quercetin from plant samples were discussed in detail. This review provides valuable information on efficient and sensitive methods for separating and purifying quercetin in plants. It also provides a technical reference for further investigation of the separation and analysis of active ingredients in natural products.

Determination of Se and Te by hydride generation-inductively coupled plasma mass spectrometry after mixed-acid digestion of tungsten ores

Se and Te in tungsten ores are important parameters for exploring the metallogenetic process of tungsten ores; however, due to their high refractory, low abundance, extreme volatilization, as well as the complex matrix interference during analysis, it is a challenge to accurately determining their concentrations in tungsten ores. This study presents a method of combining hydride generation device with inductively coupled plasma mass spectrometry (HG-ICP-MS) to determine the contents of Se and Te in tungsten ores. As a pre-processing step, tungsten ores were dissolved in the mixture of HF + HNO3 + HClO4 and microwaved for digestion. The analytical results show that the main matrix components (K, Na, Ca, Mg, Fe, Mn and Pb) in tungsten ores have no interference, and the interference of W, Cu, Zn and Bi can be eliminate by adding an appropriate amount of Fe3+. The method was used to test 6 samples with different tungsten concentrations. Compared with the results of hydride generation atomic fluorescence spectrometry (HG-AFS) method, the mean values of HG-ICP-MS method showed a good consistency and the relative mean deviations of Se and Te contents were in the range of −5.2%­ to 6.2% and − 3.8%­ to 3.4%, respectively. The values of Se, Te and Te/Se ratio determined from various geological samples (30 soil and sediment samples, 30 granite samples, 25 poly-metallic sulfide ore samples and 29 tungsten ore samples) highlight their potential prospecting in the metallogenetic process of tungsten ores.

Accurate measurement of uranium and thorium in naturally occurring radioactive materials to overcome complex matrix interference

A standard addition (SA) calibration method for determining uranium and thorium in naturally-occurring radioactive materials (NORMs) was studied. Pretreatment method using fusion was established and optimized. The SA method was validated (LOD, LOQ, linearity, selectivity, and accuracy) using certified reference materials (SRM 2709a, RM-ZR, and RM-BX). The results were evaluated for bias, and a correction equation that included a contribution to the expanded uncertainty was used. All performance criteria were satisfied; the results agreed well with certified and reference values.

Colorimetric and Raman dual-mode lateral flow immunoassay detection of SARS-CoV-2N protein antibody based on Ag nanoparticles with ultrathin Au shell assembled onto Fe3O4 nanoparticles.

Serological antibody tests are useful complements of nuclei acid detection for SARS-CoV-2 diagnosis, which can significantly improve diagnostic accuracy. However, antibody detection in serum or plasma remains challenging to do with high sensitivity. In this study, Ag nanoparticles with ultra-thin Au shells embedded with 4-mercaptobenzoic acid (MBA) (AgMBA@Au) were manufactured and then assembled onto Fe3O4 surface by electrostatic interaction to construct the Fe3O4-AgMBA@Au nanoparticles (NPs) with magnetic-Raman-colorimetric properties. Based on the composite nanoparticles, a colorimetric and Raman dual-mode lateral flow immunoassay (LFIA) for ultrasensitive identification of SARS-CoV-2 nucleocapsid (N) protein antibody was constructed. The magnetic nanoparticles (Fe3O4 NPs) were acted as the core and coated a layer of AgMBA@Au particles on the surface by electrostatic interaction to prepare Fe3O4-AgMBA@Au NPs, which can amplify the SERS signal due to multiple AgMBA@Au particles concentrated on a single magnetic nanoparticle. Moreover, the Fe3O4-AgMBA@Au NPs facilitated pre-purifying sample using magnetic separation, and complex matrix interference would be greatly decreased in the detection. The Fe3O4-AgMBA@Au NPs modified with N protein recognized and bound with N protein antibodies, which were trapped on the T-line, forming color band for observing detection. Under optimal conditions, the N protein antibodies could be qualitatively detected in colorimetric mode with the visual limit of 10-8mg/mL and quantitatively detected by SERS signals between 10-6 and 10-10mg /mL with 0.08pg/mL detection limit. The coefficients variations (CV) of intra-assay was 8.0%, whereas of inter-assay was 11.7%, confirming of good reproducibility. Finally, this approach was able to discriminate between positive, negative, and weakly positive samples when detecting 107 clinical serum samples. The process enables highly sensitive quantitative assays that are valuable for evaluating disease processes and guiding treatment. Colorimetric and Raman dual-mode LFIA detection of SARS-CoV-2N protein antibody based on Fe3O4-AgMBA@Au nanoparticles.

Magnetic Fluorescent Quantum Dots Nanocomposites in Food Contaminants Analysis: Current Challenges and Opportunities.

The presence of food contaminants can cause foodborne illnesses, posing a severe threat to human health. Therefore, a rapid, sensitive, and convenient method for monitoring food contaminants is eagerly needed. The complex matrix interferences of food samples and poor performance of existing sensing probes bring significant challenges to improving detection performances. Nanocomposites with multifunctional features provide a solution to these problems. The combination of the superior characteristics of magnetic nanoparticles (MNPs) and quantum dots (QDs) to fabricate magnetic fluorescent quantum dots (MNPs@QDs) nanocomposites are regarded as an ideal multifunctional probe for food contaminants analysis. The high-efficiency pretreatment and rapid fluorescence detection are concurrently integrated into one sensing platform using MNPs@QDs nanocomposites. In this review, the contemporary synthetic strategies to fabricate MNPs@QDs, including hetero-crystalline growth, template embedding, layer-by-layer assembly, microemulsion technique, and one-pot method, are described in detail, and their advantages and limitations are discussed. The recent advances of MNPs@QDs nanocomposites in detecting metal ions, foodborne pathogens, toxins, pesticides, antibiotics, and illegal additives are comprehensively introduced from the perspectives of modes and detection performances. The review ends with current challenges and opportunities in practical applications and prospects in food contaminants analysis, aiming to promote the enthusiasm for multifunctional sensing platform research.

Rapid and interference-free quantification of nine coumarins in Cnidii fructus using HPLC-DAD assisted with second-order calibration model

High performance liquid chromatography-diode array detection (HPLC-DAD) assisted with second-order calibration model based on alternating trilinear decomposition-assisted multivariate curve resolution (ATLD-MCR) model was proposed to quantify nine coumarins in traditional Chinese medicine (TCM) samples of Cnidii Fructus. This advanced analytical strategy shows good linearity (r > 0.9991), rapidity (t < 10.50 min) and accuracy, in low chromatographic resolution data even in the presence of potential interfering species. Satisfactory qualitative and quantitative results were achieved in the presence of complex matrix interferences from the TCM samples and the second-order advantage was fully exploited. The average spiked recoveries for most target analytes are in the range of 84.1%–108.0% with the standard deviations less than 6.9%. Furthermore, the quantitative results were further compared with a classical univariate calibration applied to a series of peak area data acquired from HPLC-UV detection. Statistical parameters and analytical figures of merit were calculated according to modern analytical protocols to validate the accuracy of the proposed analytical method. The results show that the proposed analytical method had the advantages of high-efficiency, low-cost and met the requirements of green analytical chemistry. Therefore, it promises to be a potential and universal way for qualitative and quantitative analysis of coumarins in pharmaceutical and food fields.

Ultra-rapid and highly efficient enrichment of organic pollutants via magnetic mesoporous nanosponge for ultrasensitive nanosensors

Currently, owing to the single-molecule-level sensitivity and highly informative spectroscopic characteristics, surface-enhanced Raman scattering (SERS) is regarded as the most direct and effective detection technique. However, SERS still faces several challenges in its practical applications, such as the complex matrix interferences, and low sensitivity to the molecules of intrinsic small cross-sections or weak affinity to the surface of metals. Here, we show an enrichment-typed sensing strategy with both excellent selectivity and ultrahigh detection sensitivity based on a powerful porous composite material, called mesoporous nanosponge. The nanosponge consists of porous β-cyclodextrin polymers immobilized with magnetic NPs, demonstrating remarkable capability of effective and fast removal of organic micropollutants, e.g., ~90% removal efficiency within ~1 min, and an enrichment factor up to ~103. By means of this current enrichment strategy, the limit of detection for typical organic pollutants can be significantly improved by 2~3 orders of magnitude. Consequently, the current enrichment strategy is proved to be applicable in a variety of fields for portable and fast detection, such as Raman and fluorescent sensing.

An enhanced strategy integrating offline two-dimensional separation with data independent acquisition mode and deconvolution: Characterization of metabolites of Uncaria rhynchophylla in rat plasma as a case

The importance to clarify the drug metabolites is beyond doubt in view of their potential efficacy and safety. However, due to the complex matrix interference, relatively low content and the co-eluting effect, it is of a great challenge to comprehensively and systematically characterize the metabolites in vivo, especially for the traditional Chinese medicines (TCMs) due to the numerous types of components. In the present study, a comprehensive off-line two-dimensional separation system combining with data independent acquisition (DIA) mode and multi-dimensional data deconvolution method was established for chromatographic separation, data acquisition and data procession of indole alkaloids in rat plasma after intragastrically administrated with the extract of Uncaria rhynchophylla at the dose of 1 g/kg. The orthogonality of the off-line 2D separation system consisting of HILIC for first-dimensional separation and the PRLC for second-dimensional separation was valuated with the “asterisk” equations, and the results showed that off-line 2D separation system had passable orthogonality (A0 = 53.3%). Furthermore, the DIA mode was applied to capture MS/MS spectra in view of its advantage in acquiring MS data, and an effective multi-dimensional deconvolution method integrating the calculation of chemical formula, the extraction of diagnostic ion, the filter of ring double bond (RDB) and the judgement of neutral loss was established to parse the spectra for the complicated DIA data for comprehensive analysis of metabolites in rat plasma. Ultimately, a total of 127 indole alkaloids were tentatively characterized, and the main metabolic pathways were inferred as demethylation, dehydrogenation, hydroxylation and deglycosylation. The off-line two-dimensional separation system was applied for the comprehensive characterization of metabolites in vivo for the first time. This study suggested a new approach to enable the enrichment, separation and analysis of the low content components in vivo.

Research progress on sample pretreatment methods for migrating substances from food contact materials.

Excessive absorption of migrating substances from food contact materials can affect human health. Thus, it is essential to analyze the migration of contaminant from food contact materials. However, comprehensive analysis has been challenged by low concentration of migrating substances, manifold and complex matrix interference of food contact materials. Therefore, appropriate sample pretreatment methods should be applied before instrumental detection, which is essential to improve the analytical efficiency, sensitivity, and reliability. This paper systematically reviews the development of sample pretreatment methods for analysis of migrating substances from food contact materials in the past decade. To extract volatile and semi-volatile substances, headspace extraction, headspace solid phase microextraction, and purge and trap technique are discussed. For non-volatile substances, solid-liquid extraction and field-assisted extraction are usually used to extract them from food contact materials, while liquid-liquid extraction, solid phase extraction, and their corresponding microextraction techniques play important roles on enrichment process. In addition, new progress in developments of sample pretreatment methods of food contact materials is summarized, covering new devices, specific adsorbents, and sample preparation methods for rapid detection. An outlook of future prospect of sample pretreatment, especially for non-targeted analysis of non-intentionally added substances is briefly discussed.

Magnetic particles encoding a suspension probe for ultra-sensitive and quantitative determination of atrazine

As a highly toxic and widely used herbicide, atrazine poses a serious threat to food safety as well as overall environmental and human health. Due to complex matrix interference and the difficulty of signal enrichment, there is an urgent need for a convenient, fast, and ultrasensitive method that detects trace atrazine without concern for matrix effects. Here, we provide the first account of a sensitive and rapid suspension probe based on magnetic microspheres used to detect atrazine in herbs. The self-made magnetic beads featured -COOH groups and were used as the carrier to construct immunofluorescent probes. These probes then conjugated with the atrazine antigen through an activated ester method, ultimately binding to the antibody. Homogeneous detection was ensured using flow cytometry and the microflow optical channel along with allophycocyanin-conjugated goat-anti-mouse secondary antibody (APC-IgG-SecAb) as the fluorescent signal. The magnetic suspension probe allowed for high target enrichment and the inherent two-dimensional selective detection of flow cytometry effectively avoided any matrix interference. This method had good linearity across 1.69−23.19 ng mL−1. The IC50 and LOD values were 4.81 ng mL−1 and 0.95 ng mL−1, respectively; the sensitivity was increased three-fold relative to ELISA. After complete optimization, 2-N-morpholinoeth-anesulfonic acid was used as the coupling solution and maintained good mono-dispersity, stability, and reactivity for the labelled microspheres during the process. The entire experiment was simple, and effectively used reagents; moreover, both the labor required and detection time were greatly reduced. Critically, the strategy presented here greatly reduced interference from complex matrices, and saved preparation for matrix-matched solutions when different herbs were screened. Overall, this strategy was sensitive, rapid, eco-friendly, and labor-saving; collectively, these attributes make it well-suited for on-site screening of atrazine contamination and will allow for increased food safety.