[Applications of high performance liquid chromatography-mass spectrometry in proteomics].

Proteomics profiling plays an important role in biomedical studies. Proteomics studies are much more complicated than genome research, mainly because of the complexity and diversity of proteomic samples. High performance liquid chromatography-mass spectrometry (HPLC-MS) is a fundamental tool in proteomics research owing to its high speed, resolution, and sensitivity. Proteomics research targets from the peptides and individual proteins to larger protein complexes, the molecular weight of which gradually increases, leading to sustained increases in structural and compositional complexity and alterations in molecular properties. Therefore, the selection of various separation strategies and stationary-phase parameters is crucial when dealing with the different targets in proteomics research for in-depth proteomics analysis. This article provides an overview of commonly used chromatographic-separation strategies in the laboratory, including reversed-phase liquid chromatography (RPLC), hydrophilic interaction liquid chromatography (HILIC), hydrophobic interaction chromatography (HIC), ion-exchange chromatography (IEC), and size-exclusion chromatography (SEC), as well as their applications and selectivity in the context of various biomacromolecules. At present, no single chromatographic or electrophoretic technology features the peak capacity required to resolve such complex mixtures into individual components. Multidimensional liquid chromatography (MDLC), which combines different orthogonal separation modes with MS, plays an important role in proteomics research. In the MDLC strategy, IEC, together with RPLC, remains the most widely used separation mode in proteomics analysis; other chromatographic methods are also frequently used for peptide/protein fractionation. MDLC technologies and their applications in a variety of proteomics analyses have undergone great development. Two strategies in MDLC separation systems are mainly used in proteomics profiling: the "bottom-up" approach and the "top-down" approach. The "shotgun" method is a typical "bottom-up" strategy that is based on the RPLC or MDLC separation of whole-protein-sample digests coupled with MS; it is an excellent technique for identifying a large number of proteins. "Top-down" analysis is based on the separation of intact proteins and provides their detailed molecular information; thus, this technique may be advantageous for analyzing the post-translational modifications (PTMs) of proteins. In this paper, the "bottom-up" "top-down" and protein-protein interaction (PPI) analyses of proteome samples are briefly reviewed. The diverse combinations of different chromatographic modes used to set up MDLC systems are described, and compatibility issues between mobile phases and analytes, between mobile phases and MS, and between mobile phases in different separation modes in multidimensional chromatography are analyzed. Novel developments in MDLC techniques, such as high-abundance protein depletion and chromatography arrays, are further discussed. In this review, the solutions proposed by researchers when encountering compatibility issues are emphasized. Moreover, the applications of HPLC-MS combined with various sample pretreatment methods in the study of exosomal and single-cell proteomics are examined. During exosome isolation, the combined use of ultracentrifugation and SEC can yield exosomes of higher purity. The use of SEC with ultra-large-pore-size packing materials (200 nm) enables the isolation of exosomal subgroups, and proteomics studies have revealed significant differences in protein composition and function between these subgroups. In the field of single-cell proteomics, researchers have addressed challenges related to reducing sample processing volumes, preventing sample loss, and avoiding contamination during sample preparation. Innovative methods and improvements, such as the utilization of capillaries for sample processing and microchips as platforms to minimize the contact area of the droplets, have been proposed. The integration of these techniques with HPLC-MS shows some progress. In summary, this article focuses on the recent advances in HPLC-MS technology for proteomics analysis and provides a comprehensive reference for future research in the field of proteomics.

Analytical method development and dermal absorption of gallic acid, a hair dye ingredient.

Gallic acid (GA) is a phenolic compound known as 3,4,5-trihydroxybenzoic acid. GA is used as a hair dye ingredient. It is limited to be below 4.0% in Korea. Dermal absorption rate of GA has not been reported yet. In this study, an analytical method for GA was developed and validated using high-performance liquid chromatography (HPLC) in various matrices of swab, stratum corneum (SC), skin (dermis + epidermis), and receptor fluid (RF). HPLC analysis showed acceptable linearity (r2 = 0.999-0.9998), accuracy (90.3-112.8%), and precision (0.7-13.6%) in accordance with validation guidelines by Korea Ministry of Food and Drug Safety (MFDS). The dermal absorption rate of GA was determined using Franz diffuse cells. GA (4.0%) was applied to mini pig skin of 10 µl/cm2. After 30 min application, the GA was wiped out and receptor fluid sampling was continued until 24 h. After 24 h, skin was wiped off with swab and SC was collected using tape stripping. All samples were extracted with ethanol and analyzed using the validated method. The total dermal absorption rate of GA was determined to be 2.6 ± 1.3% (24 h).

Pyriproxyfen enhances germline stem cell proliferation and reduces reproduction in Drosophila by up-regulating juvenile hormone signaling.

BACKGROUND: Pyriproxyfen is an insect growth regulator (IGR) that is effective against various types of insect pests. However, the molecular mechanism underlying pyriproxyfen effects on insect reproduction remains unclear. Thus, in this study, we attempted to uncover the mechanisms underlying the impact of pyriproxyfen on the reproductive system of the model organism Drosophila melanogaster. RESULTS: A significant decrease in Drosophila reproduction was observed after pyriproxyfen treatment. The juvenile hormone (JH) titer was significantly increased (120.4%) in the ovary samples of pyriproxyfen-treated flies. Likewise, the concentrations of key enzymes and the expression of key genes related to the JH signaling pathway were also increased in the pyriproxyfen-treated group compared with the control group. Furthermore, pyriproxyfen treatment significantly increased (15.6%) the number of germline stem cells (GSCs) and significantly decreased (17%) the number of cystoblasts (CBs). However, no significant differences were observed in the number of somatic cells. We performed RNA interference (RNAi) on five key genes (Met, Tai, gce, ftz-f1, and hairy) related to the JH signaling pathway in germ cells using the germ cell-specific Gal4 driver. Interestingly, RNAi of the selected genes significantly decreased the number of both GSCs and CBs in pyriproxyfen-treated transgenic flies. These results further validate that pyriproxyfen enhances GSC proliferation by up-regulating JH signaling. CONCLUSION: Our results indicate that pyriproxyfen significantly decreases reproduction by affecting germ cells in female adult ovaries. The effect of pyriproxyfen on germ cell proliferation and differentiation is mediated by an increase in JH signaling. This study has significant implications for optimizing pest control strategies, developing sustainable agriculture practices, and understanding the mechanism of insecticide action. © 2024 Society of Chemical Industry.

A Study of the UV Spectral Features in Wine and Their Correlation with Phenolic Constituents.

BACKGROUND: This study investigated the ultraviolet (UV) absorption spectra of various types and ages of grape wines and the correlation these spectra presented with their phenolic constituents. Firstly, the differences in UV spectra were characterized for different wine samples, depending on their type and age. METHODS: The following methods were used in this study: ultraviolet visible spectrophotometry, Folin-Ciocalteu spectrophotometric method, high-performance liquid chromatography. RESULTS: Then, it was demonstrated that for identically aged wines, the 280 nm absorbance is proportional to the concentration of phenolic compounds, as determined by the Folin-Ciocalteu method. Next, an investigation was conducted into the absorption coefficients of different phenolic classes commonly found in grapes and wine. Finally, the range in variation of phenolic compounds in various types of grape wines was established. CONCLUSIONS: This work provides a methodological approach to rapidly determine the concentration of phenolic compounds in wines using UV spectroscopy, provided that their age is known. As UV spectrophotometers are available in nearly all laboratories, this may provide a cheaper and faster alternative to current methods, including high-performance liquid chromatography (HPLC).

Covalent binding of reactive anhydride of cantharidin to biological amines.

Cantharidin is a terpenoid from coleoptera beetles. Cantharidin has been used to treat molluscum contagiosum and some types of tumors. Cantharidin is highly toxic and cantharidin poisoning and fatal cases have been reported worldwide. The mechanisms underlying cantharidin-induced toxicity remain unclear. Cantharidin contains anhydride, which may react with biological amines. This study aimed to examine the chemical reactivity of cantharidin toward nucleophiles and characterize adducts of cantharidin with biological amines in vitro and in mice. Here, two types of conjugates were formed in the incubation of cantharidin under physiologic conditions with free amino acids, a mimic peptide, or amine-containing compounds, respectively. Amide-type conjugates were produced by the binding of cantharidin anhydride with the primary amino group of biological amines. Imide-type conjugates were generated from the dehydration and cyclization of amide-type conjugates. The structure of the conjugates was characterized by using the high-resolution mass spectrometry. We introduced the 14N/15N and 79Br/81Br isotope signatures to confirm the formation of conjugates using L-(ε)15N-lysine, L-lysine-15N2, and bromine-tagged hydrazine, respectively. The structure of imide conjugate was also confirmed by NMR experiments. Furthermore, the amide and imide conjugates of cantharidin with amino acids or N-acetyl-lysine were detected in mouse liver and urine. Cantharidin was found to modify lysine residue proteins in mouse liver. Pan-P450 inhibitor 1-aminobenzotriazole significantly increased the urine cantharidin-N-acetyl-lysine conjugates whereas decreased cantharidin metabolites. In summary, cantharidin anhydride can covalently bind to biological amines nonenzymatically, which facilitates a better understanding of the role of nonenzymatic reactivity in cantharidin poisoning. Significance Statement Anhydride moiety of cantharidin can covalently bind to the primary amino group of biological amines nonenzymatically. Amide and imide conjugates were generated after the covalent binding of cantharidin anhydride with the primary amino groups of amino acids, a mimic peptide, and protein lysine residues. The structure of conjugates was confirmed by 14N/15N and 79Br/81Br isotope signatures using isotope-tagged reagents and NMR experiments. This study will facilitate the understanding of the role of nonenzymatic reactivity in cantharidin poisoning.

Combined Metabolite and Transcriptomic Profiling Unveil a Potential Gene Network Involved in the Triterpenoid Metabolism of Rose roxburghii.

Rose roxburghii, a horticulturally significant species within the Rosa genus of the Rosaceae family, is renowned for its abundance of secondary metabolites and ascorbate, earning it the title 'king of vitamin C'. Despite this recognition, the mechanisms underlying the biosynthesis and regulation of triterpenoid compounds in R. roxburghii remain largely unresolved. In this study, we conducted high-performance liquid chromatography profiling across various organs of R. roxburghii, including fruit, root, stem, and leaves, revealing distinct distributions of triterpenoid compounds among different plant parts. Notably, the fruit exhibited the highest total triterpenoid content, followed by root and stem, with leaf containing the lowest levels, with leaf containing the lowest levels. Transcriptomic analysis unveiled preferential expression of members from the cytochrome P450 (CYP) and glycosyltransferase (UGT) families, likely contributing to the higher accumulation of both ascorbate and triterpenoid compounds in the fruits of R. roxburghii compared to other tissues of R. roxburghii. Transcriptomic analysis unveiled a potential gene network implicated in the biosynthesis of both ascorbate and triterpenoid compounds in R. roxburghii. These findings not only deepen our understanding of the metabolic pathways in this species but also have implications for the design of functional foods enriched with ascorbate and triterpenoids in R. roxburghii.

Authentication of ten distinctive triterpenoids in Antrodia cinnamomea serves as a crucial aspect for ensuring the quality control of associated nutraceutical products.

Edible mushroom Antrodia cinnamomea is distinctive for its use in many health supplement products in relieving of diverse health-related conditions. A. cinnamomea is known for its rich array of bioactive secondary metabolites, predominantly terpenoids, that possess anti-inflammatory properties. Despite the abundance of these compounds, only some compounds have demonstrated notable anti-inflammatory activity. Moreover, there is a lack of established quality control methods specifically tailored to the active constituents of these products. Consequently, there is a great need for the development of precise and effective quality control methods for A. cinnamomea-based products, targeting their active components to ensure the consistency and reliability of these products in harnessing their anti-inflammatory potential. Herein we report a quantitative HPLC method for better evaluating the quality of A. cinnamomea based dietary supplements. Based on their bioactivities, we selected ten benchmark compounds, i. e. antcin K, (25S)-antcin H, (25R)-antcin H, (25R)-antcin C, (25S)-antcin C, (25R)-antcin A, 15α-acetyl-dehydrosulphurenic acid, versisponic acid D, dehydroeburicoic acid, and eburicoic acid and developed and validated a HPLC-UV method for quantification of these compounds simultaneously with high sensitivity, linearity and range, precision, and accuracy. Furthermore, we applied our method to quantify the commercially available A. cinnamomea containing supplements and found that the quality of these supplements varies greatly with only one product containing good amount of the active compounds. Our method provides a needed solution to quality control problem of the highly priced A. cinnamomea food and nutraceutical products that show great variety and inconsistency.

[High performance liquid chromatography combined with the 2,2'-dithiodipyridine derivatization reaction for determination of different types of free thiols in human serum and analysis of their relationship with coronary heart disease].

Oxidative stress, which is characterized by an imbalance between antioxidants and free radicals, plays a pivotal role in the pathogenesis of coronary heart disease, a common and serious cardiovascular condition, and contributes significantly to its development and progression. Serum free thiols are crucial components of the body's antioxidant defense system. The accurate determination of serum free thiol levels provides a reference basis for understanding the body's status and monitoring the risk factors associated with the occurrence and progression of coronary heart disease. In this study, a high performance liquid chromatographic (HPLC) method based on the derivatization reaction of 2,2'-dithiodipyridine was developed to simultaneously obtain the concentrations of total free thiols (Total-SH), low-molecular-mass free thiols (LMM-SH), and protein-free thiols (P-SH) in human serum. An Agilent Eclipse XDB-C18 column (150 mm×4.6 mm, 5 µm) was used for the analysis, and gradient elution was performed at a flow rate of 1 mL/min. A 0.1% formic acid aqueous solution was used as mobile phase A, and a 0.1% formic acid acetonitrile solution was used as mobile phase B. The gradient elution program was as follows: 0-0.1 min, 12%B-30%B; 0.1-2 min, 30%B; 2-2.1 min, 30%B-100%B; 2.1-6 min, 100%B; 6-6.1 min, 100%B-12%B; 6.1-7 min, 12%B. Well-separated peaks appeared after a run time of 5 min. The peak of 2-thiopyridone represented the Total-SH content of the samples, and the peak of the pyridyldithio derivative represented the LMM-SH content. The difference between these two peaks indicated the P-SH content. The derivatization reaction conditions were optimized, and the method was validated. The method demonstrated good linearity, with a correlation coefficient ≥0.9994, over the concentration range of 31.25-1000 µmol/L. The limits of detection for Total-SH and LMM-SH were 2.61 and 0.50 µmol/L, and the limits of quantification for Total-SH and LMM-SH were 8.71 and 1.67 µmol/L, respectively. The recoveries of Total-SH and LMM-SH were in the range of 91.1%-106.0%. The intra- and inter-day precisions ranged from 0.4% to 9.1%. The developed method was used to analyze serum samples from 714 volunteers. The Total-SH concentrations ranged from 376.60 to 781.12 µmol/L, with an average concentration of 555.62 µmol/L. The LMM-SH concentrations varied from 36.37 to 231.65 µmol/L,with an average of 82.34 µmol/L. The P-SH concentrations ranged from 288.36 to 687.74 µmol/L, with an average of 473.27 µmol/L. Spearman's correlation test showed that serum thiol levels were correlated with the severity of coronary artery disease and common clinical biochemical indicators. The proposed study provides a simple and reliable HPLC method for detecting serum free thiols and exploring their relationship with coronary heart disease, offering a new reference for the study of markers related to the risk of coronary heart disease.

In-line coupling of capillary-channeled polymer fiber columns with optical absorbance and multi-angle light scattering detection for the isolation and characterization of exosomes.

Extracellular vesicles (EVs) have garnered much interest due to their fundamental role in intracellular communication and their potential utility in clinical diagnostics and as biotherapeutic vectors. Of particular relevance is the subset of EVs referred to as exosomes, ranging in size from 30 to 150 nm, which contain incredible amounts of information about their cell of origin, which can be used to track the progress of disease. As a complementary action, exosomes can be engineered with therapeutic cargo to selectively target diseases. At present, the lack of highly efficient methods of isolation/purification of exosomes from diverse biofluids, plants, and cell cultures is a major bottleneck in the fundamental biochemistry, clinical analysis, and therapeutic applications. Equally impactful, the lack of effective in-line means of detection/characterization of isolate populations, including concentration and sizing, is limiting in the applications. The method presented here couples hydrophobic interaction chromatography (HIC) performed on polyester capillary-channeled polymer (C-CP) fiber columns followed by in-line optical absorbance and multi-angle light scattering (MALS) detection for the isolation and characterization of EVs, in this case present in the supernatant of Chinese hamster ovary (CHO) cell cultures. Excellent correlation was observed between the determined particle concentrations for the two detection methods. C-CP fiber columns provide a low-cost platform (< $5 per column) for the isolation of exosomes in a 15-min workflow, with complementary absorbance and MALS detection providing very high-quality particle concentration and sizing information.

Simultaneous high-performance liquid chromatography analysis of anthraquinones in sicklepod sprouts with α-glucosidase inhibitory activity.

INTRODUCTION: Sicklepod [Cassia obtusifolia L. syn Senna obtusifolia (L.) H.S. Irwin & Barneby, Fabaceae] sprouts are promising ingredients with health-promoting benefits. Notwithstanding, the pharmacologically active compounds in sicklepod sprouts have not been studied or analysed in detail. OBJECTIVE: This study aimed to isolate and structurally identify phytochemicals showing α-glucosidase inhibitory activity in sicklepod sprouts and simultaneously quantify the compounds in the sprouts to determine the optimal cultivation method and germination time to maximise active compounds. METHOD: A simultaneous high-performance liquid chromatography-ultraviolet (HPLC-UV) method with high sensitivity and accuracy was developed and used to analyse time-dependent changes in anthraquinone content during sicklepod germination. RESULTS: Thirteen anthraquinones were isolated and identified, of which six-chrysoobtusin, emodin, 1-O-methyl-2-methoxychrysophanol, 7-O-methylobtusin, chrysophanol, and physcion-showed moderate α-glucosidase inhibitory activity. The maximum content of anthraquinones in a sprout was observed on Day 5 under both light and dark conditions. CONCLUSION: The findings of this study revealed that sicklepod sprouts which are promising functional food materials contain a variety of anthraquinones.

Determination of Methamphetamine by High-Performance Liquid Chromatography in Odor-Adsorbent Material Used for Training Drug-Detection Animals.

The objective of the present report was to develop and validate a simple, sensitive, and selective analytical method for the determination of methamphetamine in an odor-adsorbent material (gauze) which was used to improve and standardize the training method used for drug-detection animals. High-performance liquid chromatography (HPLC) was performed using a Spherisorb ODS2 C18 column (200 mm × 4.6 mm, 5 µm), with a mobile phase consisting of a 0.25% methanol/triethylamine aqueous solution (V:V = 20:80), the pH of which was adjusted to 3.1 using glacial acetic acid, at a flow rate of 1.0 mL/min. The column temperature was 25 °C, and the detection of the analytes was performed at a wavelength of 260 nm. Methamphetamine showed good linearity (R2 = 0.9999) in the range of 4.2~83.2 mg/mL. The stability of the test material was good over 24 h. The precision of the method was good, with an average spiked recovery of 86.2% and an RSD of 2.9%. The methamphetamine content in the gauze sample was determined to be 7.8 ± 2.2 µg/sample. A high-performance liquid chromatography (HPLC) method was optimized and validated for the determination of methamphetamine in adsorbent materials (gauze). Validation data in terms of specificity, linearity, the limit of detection and the limit of quantification, reproducibility, precision, stability, and recovery indicated that the method is suitable for the routine analysis of methamphetamine in adsorbent materials (gauze) and provided a basis for training drug-detection animals.

Determination of carbohydrate content in kenaf degumming wastewater and converting them to carbon dots.

The traditional textile degumming process produces abundant wastewater, which contains a lot of monosaccharides and oligosaccharides. It is of great economic and environmental significance to utilize these carbohydrates in high value. In this study, high performance liquid chromatography (HPLC) was used to analyze the carbohydrate components in kenaf degumming wastewater, and then the production of C-dots using the wastewater was explored. The results showed that the types and content in the degumming wastewater were monosaccharides (glucose, xylose and arabinose) and oligosaccharides (dextran, xylan and araban). The carbohydrate (mainly glucan and xylan) content in wastewater accounted for 91.16 % of the total carbohydrates weight loss in kenaf degumming process. By using hydrolysis and hydrothermal reaction on kenaf degumming wastewater, blue-green carbon dots (C-dots) with good performance were prepared and successfully applied to anti-counterfeiting printing. In particular, the as-prepared C-dots prepared from kenaf degumming wastewater with urea added (WUC-dots) showed an excitation-dependent photoluminescence (PL) spectrum and quantum yield (QY) of 2.4 % in aqueous solution. The fluorescent code exhibited a clear outline, excitation-tunable color and good stability, showing a great potential for anti-counterfeiting system.

Profiling Protein-Protein Interactions in the Human Brain by Refined Cofractionation Mass Spectrometry.

Proteins usually execute their biological functions through interactions with other proteins and by forming macromolecular complexes, but global profiling of protein complexes directly from human tissue samples has been limited. In this study, we utilized cofractionation mass spectrometry (CF-MS) to map protein complexes within the postmortem human brain with experimental replicates. First, we used concatenated anion and cation Ion Exchange Chromatography (IEX) to separate native protein complexes in 192 fractions and then proceeded with Data-Independent Acquisition (DIA) mass spectrometry to analyze the proteins in each fraction, quantifying a total of 4,804 proteins with 3,260 overlapping in both replicates. We improved the DIA's quantitative accuracy by implementing a constant amount of bovine serum albumin (BSA) in each fraction as an internal standard. Next, advanced computational pipelines, which integrate both a database-based complex analysis and an unbiased protein-protein interaction (PPI) search, were applied to identify protein complexes and construct protein-protein interaction networks in the human brain. Our study led to the identification of 486 protein complexes and 10054 binary protein-protein interactions, which represents the first global profiling of human brain PPIs using CF-MS. Overall, this study offers a resource and tool for a wide range of human brain research, including the identification of disease-specific protein complexes in the future.

Efficient Synthesis and HPLC-Based Characterization for Developing Vanadium-48-Labeled Vanadyl Acetylacetonate as a Novel Cancer Radiotracer for PET Imaging.

Bis(acetylacetonato)oxidovanadium(IV) [(VO(acac)2], generally known as vanadyl acetylacetonate, has been shown to be preferentially sequestered in malignant tissue. Vanadium-48 (48V) generated with a compact medical cyclotron has been used to label VO(acac)2 as a potential radiotracer in positron emission tomography (PET) imaging for the detection of cancer, but requires lengthy synthesis. Current literature protocols for the characterization of VO(acac)2 require macroscale quantities of reactants and solvents to identify products by color and to enable crystallization that are not readily adaptable to the needs of radiotracer synthesis. We present an improved method to produce vanadium-48-labeled VO(acac)2, [48V]VO(acac)2, and characterize it using high-performance liquid chromatography (HPLC) with radiation detection in combination with UV detection. The approach is suitable for radiotracer-level quantities of material. These methods are readily applicable for production of [48V]VO(acac)2. Preliminary results of preclinical, small-animal PET studies are presented.

PEG-Lipid-PLGA Hybrid Particles for Targeted Delivery of Anti-Inflammatory Drugs.

Hybrid nanoparticles (HNPs) were designed by combining a PLGA core with a lipid shell that incorporated PEG-Lipid conjugates with various functionalities (-RGD, -cRGD, -NH2, and -COOH) to create targeted drug delivery systems. Loaded with a neutral lipid orange dye, the HNPs were extensively characterized using various techniques and investigated for their uptake in human monocyte-derived macrophages (MDMs) using FC and CLSM. Moreover, the best-performing HNPs (i.e., HNP-COOH and HNP-RGD as well as HNP-RGD/COOH mixed) were loaded with the anti-inflammatory drug BRP-201 and prepared in two size ranges (dH ~140 nm and dH ~250 nm). The HNPs were examined further for their stability, degradation, MDM uptake, and drug delivery efficiency by studying the inhibition of 5-lipoxygenase (5-LOX) product formation, whereby HNP-COOH and HNP-RGD both exhibited superior uptake, and the HNP-COOH/RGD (2:1) displayed the highest inhibition.

Thermodynamic Characteristics and Selectivity of the Liquid-Phase Adsorption of Aromatic Compounds on Hypercrosslinked Polystyrene Networks with Ultimate-High Crosslinking Densities by Data of Liquid Chromatography.

This study delves into the thermodynamics of liquid-phase adsorption on hypercrosslinked polystyrene networks (HPSNs), widely recognized for their distinct structure and properties. Despite the considerable progress in HPSN synthesis and characterization, gaps persist regarding the chromatographic retention mechanism, thermodynamics of adsorption, and their impact on the adsorption selectivity, especially in the case of networks with ultra-high crosslinking densities (up to 500%). Utilizing high-performance liquid chromatography (HPLC), we have explored, for the first time, the thermodynamic intricacies of liquid-phase adsorption onto HPSNs crosslinked in the entire range of the crosslinking degree from 100 to 500%. Our findings reveal the dependences of thermodynamic characteristics and selectivity of adsorption on the crosslinking degree, textural features, and liquid-phase composition in the region of extremely low adsorbent surface coverages (Henry's range). We have detected that, in the case of HPSNs, the dependence of the thermodynamic characteristics of adsorption on the liquid-phase composition is different than for classical HPLC stationary phases. Moreover, we scrutinize the impact of the molecular structure of the studied aromatic compounds on the thermodynamic characteristics and selectivity of the liquid-phase adsorption on HPSNs. Investigating liquid-phase adsorption selectivity, we demonstrate the pivotal role of π-π interactions in separating aromatic compounds on HPSNs. Eventually, we unveil that the thermodynamic characteristics of adsorption peculiarly depend on the crosslinking degree due to the profound impact of the crosslinking on the electronic density in benzene rings in HPSNs, whereas the separation throughput peaks for the polymer with a 500% crosslinking degree, attributed to its exceptionally rigid network structure, moderate swelling and micropore volume, and minimum specific surface area.

Using QuEChERS and HPLC Method to Monitor the Background Concentration of Polycyclic Aromatic Hydrocarbons in Commercial Black Tea Leaves and Infusions in Taiwan.

Tea is an integral part of Taiwanese culture and is a popular drink as it contains many beneficial compounds. However, during the processing of tea, polycyclic aromatic hydrocarbons (PAHs) may form. This study investigated the concentrations of PAH4 in different black tea leaves and tea infusions based on the origin of the tea. The samples were extracted using QuEChERS, while the content of PAH4 was analyzed by high performance liquid chromatography coupled to a fluorescence detector (HPLC-FLD). The content of PAH4 in the tea leaves ranged from 2.88 µg/kg to 218.2 µg/kg (dry weight), with the highest concentration being found in teas from Vietnam. The concentration of BaP ranged from ND to 47.92 µg/kg. The release of PAH4 from tea leaves to tea infusions was significantly low, with the highest transfer being 25.8%. In this study, all PAH4 compounds in commercial black tea leaves can be detected by QuEChERS extraction with a simple HPLC method.

Time-dependent changes in retinoids content in liver and adipose tissue after feeding of a vitamin A-deficient diet to mice.

Vitamin A is an important nutrient for multiple physiological functions. To elucidate the role of vitamin A in vivo, vitamin A-deficient diets have been often used in mice to establish a vitamin A-deficiency model. However, the information on the appropriate feeding periods and time course of changes in vitamin A content in organs after the start of vitamin A-deficient diet feeding is lacking. This study aimed to assess the retinoids levels in liver and white adipose tissue in mice fed a vitamin A-deficient diet for £8 weeks. High-performance liquid chromatography was used to measure the retinoids levels in liver and white adipose tissue every 2 weeks for £8 weeks. Vitamin A-deficient diet feeding significantly decreased retinol in the liver over 6 weeks, but retinyl palmitate, a main storage form of vitamin A, was not changed over 8 weeks. The plasma retinol level remained constant throughout the experiment. In white adipose tissue, retinyl palmitate gradually decreased over 8 weeks. These results indicate that vitamin A-deficient diet feeding longer than 6 weeks reduced retinol in liver and retinyl palmitate in white adipose tissue over 8 weeks, although it is not enough for the induction of a whole-body vitamin A deficiency.

A new multi-template molecularly imprinted polymer for separation and purification of dioscin, protodioscin, and diosgenin from purple yam.

Saponin is an essential natural compound in purple yams with high nutritional and medicinal value. In this work, a multitemplate molecule-imprinted polymer (MMIP) was synthesized with dioscin, protodioscin, and diosgenin templates. The MMIPs were characterized with scanning electron microscopy, thermogravimetric analysis, Brunauer-Emmett-Teller (BET) adsorption, and Fourier transform infrared spectroscopy. The efficacy of the MMIPs was assessed with static, dynamic, selective adsorption, desorption, and reusability experiments. The three saponins were selectively extracted and determined by MMIP-high-performance liquid chromatography. The polymer morphology was regular and spherical. The amount of the MMIP adsorbed was 74.825 mg/g, and the imprinting factor was 2.1. The MMIP adsorbed the three saponins from purple yam extract, with recovery rates of 95.5-103.43 % and desorption rates of 85 %-98 %. In addition, the MMIPs were reused at least six times. These results demonstrated that the MMIPs efficiently and selectively extracted dioscin, protodioscin, and diosgenin from food matrices at high rates.

[Simultaneous determination of four N-lauryl amino acid surfactants in facial cleansers by high performance liquid chromatography-ultraviolet detection].

Significant developments have recently been achieved in the field of N-lauryl amino acid (NLAA) surfactants derived from renewable resources. Compared with conventional surfactants, NLAAs exhibit remarkable surfactant properties, exceptional biodegradability, good biocompatibility, and high safety profiles. These attributes have led to the widespread use of NLAAs in personal-care products. The detection methods employed for NLAAs include two-phase titration (TT), spectrophotometric analysis (SA), and high performance liquid chromatography (HPLC). However, because both TT and SA measure the total concentration of anionic active matter, identifying and quantifying individual compounds in a sample containing multiple anionic surfactants is impossible. The presence of cationic surfactants in the sample also introduces interferences, which lead to significant errors. Compared with TT and SA, HPLC offers direct and rapid testing procedures. However, compounds with no or weak UV-visible light absorption exhibit low sensitivity when detected by UV, necessitating the use of detectors such as differential refractive index detectors (RIDs), evaporative light scattering detectors (ELSDs), or charged aerosol detectors (CADs). Most HPLC users consider UV light as the fundamental configuration of the instrument, and other detectors are less commonly employed. Therefore, establishing a new HPLC method suitable for the UV detection of NLAAs is of practical significance. In this study, a novel HPLC-UV method was developed for the simultaneous detection of N-lauryl glutamine (LG), N-lauryl glycine (LC), N-lauryl alanine (LA), and N-lauryl sarcosine (LS) by optimizing the mobile-phase composition and selecting an appropriate chromatographic column and detection wavelength. The samples were mixed with acetonitrile-0.10% H3PO4 aqueous solution (60∶40, v/v) and sonicated for 10 min, then stayed at room temperature for 5 min. Subsequently, the mixture was filtered through a 0.22 µm filter membrane and separated on an Agilent Eclipse Plus C18 column (150 mm×4.6 mm, 5 µm). The mobile phase used for separation consisted of acetonitrile-0.10% H3PO4 aqueous solution at a flow rate of 1.0 mL/min. The detection wavelength was set at 205 nm, and the injection volume was 10 µL. The results demonstrated that the four NLAAs exhibited good linearity in the range of 2.0-800.0 mg/L, with correlation coefficients (r)≥0.9995. The limits of detection (LODs) ranged from 0.17 to 0.49 mg/L, and limits of quantification (LOQs) ranged from 0.57 to 1.63 mg/L. The relative standard deviations (RSDs) for precision, repeatability, and stability over 24 h were all below 2.0%. Using this method, the NLAA contents of five facial-cleanser products were determined. The results demonstrated that all five samples contained one or more NLAAs, and the total NLAA contents ranged from 64.58 to 97.01 mg/g. The five spiked-sample recoveries of the NLAAs at four different spiked levels (0.60, 4.50, 15.00, 24.00 mg/g) ranged from 94.3% to 107.4%, indicating satisfactory accuracy. However, the actual NLAA composition and label for one facial-cleanser product were not consistent with our test results. This finding demonstrates the necessity of strengthening market monitoring through testing. The proposed method has the advantages of simple pretreatment, rapid testing, good precision, high accuracy, and appropriate stability. Thus, it is suitable for the determination of NLAA contents in facial cleansers and provides an effective technical reference for the raw-material purity assessment, synthetic yield detection, and product quality control of this type of surfactant.