ELECTROPHORESIS最新文献

Pig skin and water buffalo hides were partially hydrolyzed to produce a heterogeneous mixture of polypeptides, known as gelatin, a commonly used food additive. Specific peptide markers were explored in the context of authentication and relative quantification of water buffalo hide gelatin (BHG) and porcine skin gelatin (PSG) via multiple reaction monitoring-mass spectrometry (MRM-MS). Tryptic gelatin peptides were separated and analyzed with ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), and five unique peptide biomarkers were selected for BHG and PSG. Gelatin extraction from BHG and PSG spiked chicken meat patties (CMP) followed by LC-MS/MS MRM-MS revealed two unique bovine gelatin peptides of m/z 781.336 and 852.718 and three unique porcine gelatin peptides of m/z 774.570, 971.776, and 727.436. The optimized MRM-MS protocol was efficient in detecting BHG/PSG from spiked CMP up to 0.5% (w/w). Twenty-five commercial food samples were screened, among which four samples showed the presence of BHG and six samples showed the presence of PSG. The proposed LC-MS/MS MRM strategy provides an efficient and sensitive authentication and traceability of gelatin-containing highly processed food, bakery, and confectionery products.

Advancements in food technology have increased the need for thorough analysis to ensure food safety, quality, and compliance with regulatory requirements. Capillary electrophoresis-mass spectrometry (CE-MS) has emerged as a powerful tool in food analysis due to its high separation efficiency, low sample consumption, and ability to handle complex matrices. However, challenges such as the use of volatile running buffers and maintaining the stability of the electrical circuit connecting the CE and MS systems have been addressed through advancements in interface designs, such as sheathless systems and optimized sheath-liquid compositions. Online and offline preconcentration techniques have significantly enhanced CE-MS sensitivity (up to 1000-fold) through stacking methods such as large volume sample stacking (LVSS) and dynamic pH junction stacking. Meanwhile, offline sample preparation techniques, such as solid-phase extraction (SPE) and liquid-based methods, are essential for removing matrix interferences and preconcentrating targeted analytes. This review explores both online and offline preconcentration methods and emphasizes the importance of CE-MS in helping researchers develop effective strategies for selecting the best preconcentration methods for food analysis.

Induction heating is one of the cleanest and most efficient methods for heating materials, utilizing electromagnetic fields induced through AC electric current. This article reports an analytical solution for transient heat transfer in a three-dimensional (3D) cylindrical object under induction heating. A simplified form of Maxwell's equations is solved to determine the heat generation inside the cylinder by calculating the current density distribution within the body. The temperature within the solid is found from the solution of the unsteady heat equation based on Green's function. Owing to multiple spatial dimensions and time, a separation of variables technique is used to find Green's function. In addition, an innovative algorithm is proposed to take care of the variable material properties in analytical treatment. The analytical solution for temperature is verified with the data obtained from experiments for identical operating conditions. The analytical solution is used to study the impact of heat transfer coefficient and input AC current frequency and amplitude during transient heat diffusion. Our analytical solution suggests that the temperature-dependent material properties significantly affect the thermal response within the solid. Unlike many other conventional heating methods, the thermal boundary condition changes with time in induction heating, which makes our solution much more challenging.

A significant limitation of imaged capillary electric focusing (icIEF) is the inability to identify and characterize specific species in the electropherogram. This has led to the development of complementary ion-exchange chromatography (IEX)-based methods that are amenable to either fraction collection and subsequent characterization or online IEX coupled to mass spectrometry. To overcome this limitation while maintaining the use of icIEF, novel approaches, including an icIEF separation and fractionation technology (MauriceFlex, ProteinSimple), have been developed. This approach enables the fractionation of various icIEF peaks, which can then be characterized by mass spectrometry to confirm the identity of the separated charged species. Herein, the MauriceFlex technology was applied to adeno-associated viral (AAV) gene therapy products, which contain a DNA transgene packaged into a protein capsid and have shown tremendous therapeutic potential in recent years. Utilizing the MauriceFlex system, we developed an approach for the separation of charged species from AAV capsid viral proteins (VP) by icIEF and subsequent characterization by liquid chromatography and mass spectrometry (LC–MS). When applying the same sample preparation, charge profiles of AAV capsid proteins on the MauriceFlex instrument were demonstrated to be consistent with those from the original Maurice platform, the industrial gold standard. Optimization of the VP icIEF fractionation method required the development of a method for low concentration samples, optimization of mobilization conditions, enhancement of fraction recovery, and maintenance of protein stability post fractionation. Herein, we were able to successfully collect charge-separated VP fraction samples and subsequently analyze them by MS analysis. In addition, a workflow for AAV capsid protein characterization based on icIEF separation and fractionation coupled with downstream LC–MS has been established for the confirmation of VP identity and additional characterization of capsid protein heterogeneity.

Computer simulation was utilized to characterize the electrophoretic processes occurring during the enantioselective capillary electrophoresis-mass spectrometry (CE-MS) analysis of ketamine, norketamine, and hydroxynorketamine in a system with partial filling of the capillary with 19 mM (equals 5%) of highly sulfated γ-cyclodextrin (HS-γ-CD) and analyte detection on the cathodic side. Provided that the sample is applied without or with a small amount of the chiral selector, analytes become quickly focused and separated in the thereby formed HS-γ-CD gradient at the cathodic end of the sample compartment. This gradient broadens with time, remains stationary, and gradually reduces its span from the lower side due to diffusion such that analytes with high affinity to the anionic selector become released onto the other side of the focusing gradient where anionic migration and defocusing occur concomitantly. The analytes that remain focused until the migrating HS-γ-CD concentration boundary arrives at the cathodic end of the sample compartment become gradually released into the cathodic part and migrate in the absence of HS-γ-CD toward the detector. This behavior is dependent on the length of the HS-γ-CD zone in the cathodic part of the electrophoretic column, the initial sample zone length, and the sample matrix. The data presented reveal the possibility that only one of the enantiomers of an analyte migrates toward the detector, whereas the other is lost for the analysis, or that both enantiomers migrate toward the cathode but do not separate. Enantiomer separation followed by migration toward the cathode can only be achieved for analytes with rather low complexation constants, such as hydroxynorketamine assessed in this work, and is dependent on the slope of the HS-γ-CD focusing gradient. The gained insights illustrate that dynamic simulation is an indispensable tool to investigate electrophoretic processes of complex systems.

Western flower thrips, Frankliniella occidentalis (Thysanoptera: Thripidae) is an invasive agricultural pest with developed resistance to abamectin in some strains due to frequent treatment with the pesticide. In this study, we examined differentially expressed proteins (DEPs) between abamectin-resistant (Aba^R; under abamectin selective pressure) and susceptible strains (Aba^S; without abamectin selective pressure) of F. occidentalis. Proteins were isolated from second instar larvae of both strains and separated via two-dimensional polyacrylamide gel electrophoresis. Nano-flow liquid chromatography–tandem mass spectrometry identified selected protein spot features. From 70 DEPs, 43 spot features were identified: A total of 23 showed an increase in abundance, and 20 were down-regulated in response to abamectin pressure. The enzymatic and structural proteins were classified into the functional groups of macromolecular metabolisms, signaling and cellular processes, immune system, genetic information processing, and exoskeleton-related proteins. The up-regulation of exoskeleton-related proteins may contribute to forming a thicker cuticle, potentially hindering abamectin penetration, which is an interesting finding that needs further investigation. Two novel proteins, triacylglycerol lipase and cuticle protein CPF 2, were only expressed in Aba^R. This work provides insights into abamectin resistance mechanisms in F. occidentalis, which will provide important information for developing insecticide resistance management approaches for this pest.