Journal of Chromatography A最新文献

The concentration of chlorpyrifos (CPF) in aqueous samples was determined using a novel molecularly imprinted dispersive solid-phase extraction (MISPE) approach that was presented in this research. Using a non-covalent molecular imprinting technique, a biochar (BC)-functionalized molecularly imprinted polymers (MIPs) (BC-MIPs) was created. These MIPs were used in dispersive solid-phase extraction (DSPE) in conjunction with high-performance liquid chromatography with photodiode array detection (HPLC-PDA) to detect CPF in aqueous samples with high sensitivity. Using methacrylic acid (MAA) as the monomer and ethylene glycol dimethacrylate (EGDMA) as the cross-linker, BC-MIPs were created using CPF as a template. By using the suggested dispersive solid-phase extraction (DSPE) approach, the efficiency of the synthesized BC-MIPs granules was evaluated. Analytical performance of the devised DSPE-HPLC-PDA technique was assessed under optimal settings. The optimized parameters included extraction time, aqueous sample pH, desorption time and desorption reagents. Compared with the traditional method, the established method has better selective adsorption capacity, reusability and sensitivity for CPF. The suggested method presented that limit of detection and limit of quantification were 1.0 ng/mL and 4.0 ng/mL, along with excellent linear range (4.0-1500 ng/mL) with coefficients of determination (R²=0.9982). The established method was successfully used to determination CPF in aqueous samples from the Baisha River in Qingdao, with the advantages of accuracy (recoveries: 81.2 %-103.6 %, RSDs≤9.2 %), speed (CPF-BC-MIPs-DSPE time: 75 min; HPLC-PDA time: 12 min), selectivity (imprinting factor: 4.24), and economy (50 mg of adsorbent synthesized using cheap straw and 1 mL of solvents), which partially conform to the current advanced principle of "3S+2A" in analytical chemistry. The BC-MIPs granules shown potential for CPF preconcentration in complicated samples and were effective carriers for the selective adsorption of CPF.

Here we covalently constructed abundant long-chain hydroxyl groups-functionalized magnetic microporous organic networks (MMON-2OH) for detection of eight Triazine herbicides (THs) in honey and water samples. MMON-2OH owned a high surface area (287.86 m²/g), enhanced water compatibility, and increased exposure of long-chain hydroxyl groups, which significantly improved enrichment capacity for THs. Theoretical analyses and characterization data revealed interaction mechanisms, including hydrogen bonds (N-H···O and O-H···N), halogen bond (Cl···N) and π stackings (NH-π, CH-π and π-π). This approach was developed for the detection of THs, achieving a low detection limit 0.03∼0.6 ng⋅L^-1 for water, and 0.006∼0.134 μg·kg^-1 for honey. Trace concentrations of THs, ranging from 1.0∼21.2 ng⋅L^-1 in surface water and 0.1∼0.9 μg·kg^-1 in honey, were successfully detected. Sample spiked recovery experiments demonstrated recoveries between 72.1-116.2 %, validating accuracy and applicability of method. This study realizes a speedy and sensitive determination of THs, showcasing potential of MMON-2OH in pollutant removal and food safety maintenance.

Microfibres released from textiles are one of the most common types of microplastics (MPs) found in the environment. Whether they are synthetic or natural, they can undergo degradation in different environmental matrices. This may result in the leaching of a variety of chemicals, mainly textile dyes and additives of high toxicity that need to be regulated. A novel method was developed, validated and applied to identify and quantify these types of compounds present in a hydrolytic alkaline degradation solution (neutralized), but it can also be used in similar laboratory-simulated solutions, and seawater. The employed solution was utilized in an accelerated degradation simulation of two different polyester (PES) fibre types. Thirteen compounds were extracted and quantified using a solid-phase extraction protocol followed by HPLC-HRMS/MS. Intra-day (Intra-R) and inter-day (Inter-R) precision ranged from 0.02 to 6.23 % and 0.08 to 8.85 %, respectively, while linearity (R²) values were >0.9980. The limits of detection (LOD=0.7- 3.3 ng mL^-1) and quantification (LOQ=0.5- 10 ng mL^-1) were determined for the proposed method. Good recoveries were obtained for all compounds studied (65-120 %), while matrix effects ranged from -6 to 30 %, depending on the analyte. Ten compounds were detected and quantified in the degradation solution of the two different polyester fibres, with three (benzothiazole, 4-nitrophenol, 2,6-dichloro-4-nitroaniline) being PES type specific, while the rest were found in both types. A non-target analysis allowed the identification of a wider range of possible leachates (55 compounds in positive ion mode and 24 in negative).

The evolution of precursors to form secondary organic aerosol (SOA) is still a challenge in atmospheric chemistry. Chamber experiments were conducted to simulate the ambient OH oxidation of naphthalene and α-pinene, which are typical markers of anthropogenic and biogenic emissions. Particulate matters were sampled by quartz filters and were analyzed by comprehensive two-dimensional gas chromatography (GC×GC) coupled with a thermal desorption system (TD) and a mass spectrometer (MS). A four-step procedure is proposed based on chromatographic differentiation in SOA fingerprint identification, including initial resolving, translation and alignment, pixel-based differentiation, and marker identification. Data processing begins by creating a 65-organic consensus template from peak identification results. Peaks are screened with matching factors >700. Retention time shifts of Naphthalene and α-pinene oxidation products are 0.5 min and 0.1 min respectively. A reverse matching factor >800 is used to define high-confidence compound recognition, and the ±50 retention index tolerance assists structure ID for SOA study. Two new markers are found for the first time, i.e., phthalimide in naphthalene-OH oxidation with the occurrence of NO_x, and citronellol epoxide from α-pinene-OH oxidation. Our finding offers fresh insights into the complex chemical pathways of these precursors and improving our understanding of SOA formation mechanisms. Our workflow works well for fingerprint identification and could be utilized in finding SOA intermediates and source appointments.

Analytical thin layer chromatography (TLC) is a simple yet powerful chromatographic technique that is widely used for the qualitative characterization of complex mixtures such as plant extracts. For their qualitative and visual characterisation, a large number of more or less specific colour reactions are at hand and numerous reference substances are available as well. However, the identification of extract components by colour and the comparison of retention times is not straightforward. In contrast, the coupling of TLC with MALDI-TOF mass spectrometry can enable the identification of components and contribute to the optimization of TLC protocols. One of the most important steps for a successful TLC-MALDI process is the deposition of a sufficient amount of matrix onto the TLC plate. Standard methods such as the dip-coating protocol have major drawbacks. Here we present an improved and robust procedure for matrix application by means of matrix lines. The practicability of the method was tested on plant extracts from Agrostemma githago L. and Papaver somniferum L. (opium).

As an established analytical method, high-performance thin-layer chromatography (HPTLC) offers powerful capabilities. This study focused on its application to analyze chlorinated paraffins (CP) by planar solid phase extraction (pSPE). Based on previous work, an irradiation chamber was developed to investigate the derivatization process on planar thin-layers and ensure a robust and reproducible analysis. A simple-to-handle irradiation chamber was designed to initialize the reaction between CP and the derivatization reagents o-tolidine and tetramethylbenzidine (TMB). It was shown that the complete derivatization reaction is not significantly influenced by the chain length and only depends significantly on the chlorine content of the used standards. Regarding the reaction process, a relation between the chain length and chlorine content was obtained; however, quantitative correlations cannot be found. Furthermore, the derivatization solutions were investigated in terms of stability, different concentrations, and the optimal irradiation time. The method showed robustness regarding signal intensity at irradiation times of 1 to 36 min and amounts of 10-400 ng of the technical reference CP mixture C₁₄-C₁₇ 52 % Cl. Its application to CP with chain lengths between C₁₀ and C₂₃ and chlorine content between 40 % and 70 % emphasized the method's versatility.

Traditional Chinese medicine (TCM) is a treasure of China and a crucial part of traditional medicine in the world, particularly in many oriental countries. TCM is the core and basis of traditional medicine in clinical practice for numerous diseases, and performs important function in nutraceuticals and dietary supplements. However, it is extremely difficult to extract each active ingredient from TCM to elucidate the mechanism of TCM clinical efficacy due to numerous compounds in TCM, especially trace compounds. Consequently, liquid-phase microextraction (LPME) techniques, one of the main extraction methods of active ingredients in TCM, have attracted a considerable attention from researchers. In recent years, many novel green solvents based-LPME methods have been reported, such as single-drop microextraction (SDME), hollow-fiber liquid-phase microextraction (HF-LPME), dispersive liquid-liquid microextraction (DLLME), and electro-membrane extraction (EME). Therefore, in this review, we present an up-to-date and comprehensive summary of various LPME techniques, novel green solvents, and their applications in the analysis of active ingredients within the complex TCM samples. We provide a detailed overview of the fundamental principles, modes, and the critical process parameters of the LPME techniques. In addition, we compare different types of green solvents (i.e., deep eutectic solvents, ionic liquids, magnetic ionic liquids, supramolecular solvents, switchable solvents, among others), and the advantages and disadvantages of these solvents are critically evaluated, highlighting their suitability for various applications. Finally, we elucidate the merits and demerits of different LPME methods, discuss their practical applications, and explore their future research directions. This review aims to provide a valuable resource for researchers and practitioners in the field of TCM, promoting research development and application of the advanced and environmentally friendly sample pretreatment techniques.

Our previous studies on protein adsorption onto anion-exchangers of poly(ethylenimine) (PEI)-grafted Sepharose FF (PEI-Sepharose) proved their significantly improved performance over the commercial nongrafting anion-exchangers such as Q Sepharose FF, and it was found the protein adsorption behavior on PEI-Sepharose was more sensitive to counterions (Cl^-, SCN^-, HPO₄^2- and SO₄^2-). However, the complicated role of counterions has not been well interpreted due to their distinct chemical and physical characteristics. Thus, we have further studied the counterion effects by adding two halide ions (F^- and Br^-) to explore the effects of the three halide ions on bovine serum albumin adsorption and the results were compared with previous data. Furthermore, separation of recombinant human serum albumin (rHSA) from fermentation broth was studied. It was found that the counterion preference for PEI-Sepharose increased with the charge density of the counterions, demonstrating the favorable elution by choosing a proper counterion. Moreover, uptake kinetics onto PEI-Sepharose was very sensitive to counterions, even the three halide ions. In contrast, there is little difference among the halide ions for dynamic binding capacity of PEI-Sepharose, presenting a high value (104 ± 3 mg/mL) for the three halide ions. Furthermore, PEI-Sepharose exhibited much higher rHSA separation performance over Q Sepharose FF, characterized by sharper and more symmetrical elution peaks, higher recovery, enriched eluates, and reduced use of elution salt. The high recovery (>90 %) of rHSA from the Pichia pastoris culture supernatant proved the superiority of PEI-Sepharose column in downstream processing of therapeutic proteins.

Extracellular vesicles (EVs) carrying lipids, proteins, nucleic acids and small molecular metabolites have emerged as an attractive paradigm for understanding and interfering physiological and pathological processes. To this end, selective and efficient separation approaches are highly demanded to obtain target EVs from complicated biosamples. With increasing knowledges on EV lipids, recent years have witnessed rapid advances of phospholipid-targeted affinity materials and platforms for high-performance isolation and analysis of EVs. In view of this, this review is contributed to introduce recent progresses in lipid membrane-targeted affinity strategies for EV isolation and molecular detection in biofluids. Affinity ligands including lipids, peptides, small molecules and aptamers and their molecular interactions with lipids are discussed in focus. The design, construction and mechanism of actions of affinity interfaces are summarized. The EV separation performances in complex biosamples and downstream proteomic, lipidomic and metabolic profiling are introduced. Finally, the perspectives and challenges for the development of next-generation phospholipid-targeted EV separation platforms are discussed.

A new type of sorbent functionalized with π-hole bond, perfluoronaphthyl bonded magnetic nanosorbent (Fe₃O₄@SiO₂-C₁₀F₇), was designed and synthesized. The morphology, structure and magnetic properties of the sorbent were characterized. The results of a comparative experiment with naphthyl bonded magnetic nanosorbent (Fe₃O₄@SiO₂-C₁₀H₇) revealed that the π-hole bonds between perfluoronaphthyl and PAHs improved adsorbilities for PAHs in water compared to the traditional π-π interactions between naphthyl and PAHs. A new MSPE-HPLC method for the simultaneous detection of 15 PAHs in environmental water was established based on Fe₃O₄@SiO₂-C₁₀F₇ sorbent. This method requires less sorbent, offers high sensitivity, and allows for easy operation without solvent replacement. The results revealed that the method exhibited good linearity in the range of 0.05-12 ng·mL^-1, and the recoveries of the PAHs in real samples ranged from 70.1 % to 108 % at the spiked concentration of 0.5 ng·mL^-1, except for volatile naphthalene (41.8 %). The LODs were 0.2-13.4 ng·L^-1. The results demonstrate the effectiveness of π-hole bond in extraction of PAHs, surpassing traditional π-π interaction even in water. The application of π-hole bond in sorbents offers a new interaction mode or retention mechanism in extraction processes, undoubtedly providing a fresh perspective for the design of selective sorbents.