Methanol Acid Research Articles

Macroporous resins combined with UPLC-QTRAP-MS/MS for the purification and identification of 3-deoxyanthocyanidins from Sorghum bicolor L. Moench and their bioactivities.

3-Deoxyanthocyanidins (3-DAS) are the unique flavonoid compounds in sorghum. The majority of research to date have concentrated on the biological activity and extraction of 3-DAS from sorghum and lacked systematic purification and identification investigations. Herein, a facile method for the purification of sorghum 3-DAS from the acidic methanol solution crude extract using macroporous resins (MARs) was proposed and investigated in this work. Based on the experimental data, commercial MAR AB-8 was selected to achieve the purification of sorghum 3-DAS. The adsorption-desorption experiment confirmed the optimal procedure. With this procedure, the total purity of 3-DAS was 19.32%, and 3-DAS content in the purified product was 8.4 times higher than that in the crude extract. UPLC-QTRAP-MS/MS identification indicated that the purified 3-DAS product was mainly composed of apigeninidin, luteolinidin, and their methoxy derivatives. Besides, the purified product exhibited better bioactivities than the crude extract, including the scavenging activities for DPPH, ABTS+, and hydroxyl radicals, the total antioxidant capacity, and the inhibitory effects for α-amylase, α-glucosidase, and lipase. This work provides a potential way for the large-scale purification of bioactive sorghum 3-DAS from crude extract, which is significant to deepen the applications of sorghum 3-DAS in the food nutrition and pharmaceutical industries.

Synthesis and optimization of Pt nanoparticle catalyst supported on heterogeneous composite Mo2C-N-C for acidic direct methanol fuel cell anodes

Molybdenum carbide (Mo2C) has similar d-band characteristics to platinum (Pt), so it has a similar catalytic activity to Pt. It can be used as a catalyst support or co-catalyst in the anode of direct methanol fuel cells (DMFC). The unique hexagonal crystal system structure of Mo2C is beneficial for improving the overall performance of the catalyst when combined with N-doped carbon (N-C). When Pt is loaded onto the Mo2C-N-C support, the synergistic effect between Mo2C-N-C and Pt makes the catalyst exhibit higher activity and stability in the methanol oxidation reaction. In this study, a high-quality Mo2C-N-C support was synthesized using stripped g-C3N4 as a self-sacrificing template, followed by the preparation of Pt/Mo2C-N-C catalyst via microwave-assisted glycol reduction. In acid media, the optimized Pt/Mo2C-N-C catalyst exhibited improved methanol oxidation reaction (MOR) activity and robust durability, the methanol oxidation current density reached 1.74 times that of commercial Pt/C, which was prepared under the same conditions, demonstrating the catalyst’s superior methanol oxidation activity.

Light Harvesting Materials: A Study on Förster Resonance Energy Transfer and Optoelectronic Properties of Potential Nerium oleander Flowers.

The present study focused on extracting the anthocyanin dyes in ethanol, acidic ethanol, methanol, and acidic methanol solvents from Nerium oleander flowers by a simple maceration extraction process. FTIR spectroscopy and vibrational studies have confirmed the existence of polyphenolic groups in 2-phenyl chromenylium (anthocyanin) dyes. The optoelectronic results show the least direct bandgap (2.89 eV), indirect bandgap (1.98 eV), Urbach energy (0.120 eV), high refractive index (1.654), dielectric constant (3.294) and high optical conductivity (1.813 103 S/m) for the anthocyanin dye extracted found in acidic ethanol solvent. The photoluminescence properties such as Stokes' shift, quantum yield, and lifetime results show that anthocyanin dyes are promising candidates for red-LEDs and optical materials. The excellent correspondence between the absorption and emission spectra reinforces that the anthocyanins are efficient (89%) FRET probes. Further, the donor and acceptor undergo redshift in excitation and emission spectra in all studied solvents. The photometric properties such as CIE, CRI, CCT and color purity results of anthocyanins in all studied solvents revealed that this material exhibits pink to red shades (x = 0.40 → 0.50 and y = 0.46 → 0.39) and is well suitable for have great potential in the manufacturing of Organic-LEDs and other optoelectronic device applications.

Quality Results of Cotton Fabric Coloring with Mangsi (Phyllanthus Reticulatus) Fruit Extract

The research was done to analyze the quality of the coloring result of mangsi (phyllanthus reticulatus) fruit extract as natural dyes in cotton fabric dyeing. Extraction method was carried out through maceration process using some solvents namley water, ethanol, acidic ethanol, methanol, and acidic methanol in a ratio of 1:10 with pre-mordanting and fixation using mordant alum, calcium carbonate, and ferrous sulphate. The conducted observations included color direction test, color opacity test and color fastness to soap washing test. The result of color direction was brown to yellow-orange and blue to dark blue. The value of color opacity on cotton fabrics was in the “medium” to “very opaque” color category. The resulting value of color fastness to soap washing test was in the “good” to “poor” category. The dyeing results on cotton fabric generated an even color.

Efficient catalysis for acidic methanol oxidation: Exploration of a Low-Platinum quaternary alloy catalyst via a Two-Step method

The quest for platinum-based catalysts with enhanced catalytic efficacy and durability during the methanol oxidation reaction (MOR) has been a focal point in energy conversion science. Traditional platinum-based catalysts are often constrained by their high platinum content, which escalates economic costs and complicates experimental protocols. In this study, we introduce a low-platinum-loaded catalyst synthesized via a two-step method, which incorporates a four-component alloy. This innovative approach significantly reduces platinum content while maintaining superior catalytic performance through precise control over the alloy’s composition and structure. The two-step synthesis methodology streamlines the conventional multi-step processes, enhancing the catalyst preparation’s efficiency and reproducibility. The resulting PtCoSnCu/N-C alloy catalyst exhibits remarkable catalytic activity in methanol solution, with mass activity and specific activity that are 9.73 and 9.75 times higher, respectively, than those of commercial platinum on carbon (Pt/C) catalysts. Notably, the optimized PtCoSnCu/N-C alloy catalyst demonstrates exceptional long-term stability, outperforming Pt/C in aging and extended stability tests. Density functional theory (DFT) calculations elucidate the optimization of the electronic structure and the synergistic effect of surface atoms in the PtCoSnCu/N-C catalyst, which mitigates the adsorption energy of CO molecules and enhances the utilization rate of active sites during the oxidation process. This research presents a paradigm-shifting low-platinum catalyst strategy for methanol fuel cells, establishing a theoretical foundation for catalyst design and optimization.

Isolation of a novel Bacillus subtilis HF1 strain that is rich in lipopeptide homologs and has strong effects on the resistance of plant fungi and growth improvement of broilers.

Bacillus subtilis is an important probiotic microorganism that secretes a variety of antimicrobial compounds, including lipopeptides, which are a class of small molecule peptides with important application value in the fields of feed additives, food, biopesticides, biofertilizers, medicine and the biological control of plant diseases. In this study, we isolated a novel B. subtilis HF1 strain that is rich in lipopeptide components and homologs, has a strong antagonistic effect on a variety of plant fungi, and is highly efficient in promoting the growth of broilers. The live B. subtilis HF1 and its fermentation broth without cells showed significant inhibitory effects on 20 species of plant fungi. The crude extracts of lipopeptides in the fermentation supernatant of B. subtilis HF1 were obtained by combining acid precipitation and methanol extraction, and the lipopeptide compositions were analyzed by ultrahigh-performance liquid chromatography with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF-MS). The results showed that HF1 could produce 11 homologs of surfactin and 13 homologs of fengycin. Among the fengycin homologs, C13-C19 fengycin A and C15-C17 fengycin B were identified; among the surfactin homologs, C11-C17 surfactin A and C13-C16 surfactin B were characterized. C13 fengycin A, C11 surfactin A and C17 surfactin A were reported for the first time, and their functions are worthy of further study. In addition, we found that HF1 fermentation broth with and without live cells could be used as a feed additive to promote the growth of broilers by significantly increasing body weight up to 15.84%. HF1 could be a prospective strain for developing a biocontrol agent for plant fungal diseases and an efficient feed additive for green agriculture.

Comparison of phenolics, flavonoids and anthocyanin in pigmented and non-pigmented maize in bangladesh

In the present study the compositions of phenolics, flavonoids and anthocyanins in a purple maize (SAU Bhutta 3) variety were determined and compared its phytonutrients with those of other maize varieties cultivated in Bangladesh. The SAU purple maize contained 106.0 ± 8.3 and 165.1 ± 8.0 mg /100 g of methanol soluble and acidic methanol soluble polyphenols, respectively. The SAU Bhutta 3 had the greatest amount of flavonoids (77.0 ± 10.0 mg /100 g) and anthocyanins (69.0 ± 5.0 C3G equv./100 g). Nevertheless, the SAU white maize variety had 31.0 ± 2.0, 47.0 ± 4.4 mg FAE/100 g and 9.0 ± 2.0 mg CE/100 g of free and bound phenolics and total flavonoids, respectively, which were lower than those of the SAU Bhutta 3. Again, the SAU red maize contained the lowest level of total anthocyanin (4.11 ± 1.2 mg C3G/100 g). The SAU Bhutta 3 exhibited higher proportions of insoluble phenolics compared to total phenolics and flavonoids compared to insoluble phenolics. Overall, the SAU Bhutta 3 contained relatively high amounts of phenolics, flavonoids and anthocyanins; thus, this particular maize variety shows significant potential for future utilization. Bangladesh J. Bot. 53(3): 495-502, 2024 (September)

Extraction and Quantification of Phenolic Compounds in Maize.

Plants accumulate hundreds of thousands of specialized metabolites that participate in their interactions with the environment. Among these compounds, phenolics represent a large class, and they play important physiological roles, such as providing a first barrier against pathogens, cues to pollinators, and radiation protection. Maize is one of the most important crops worldwide for food, animal feed, and biofuels, and it has the potential to accumulate different phenolics in vegetative tissues as well as in seeds. Recent studies have identified a large number of phenolic compounds-with a diversity of chemical decorations-in different maize tissues, but these likely represent just a fraction of the metabolic diversity of maize. In this protocol, we describe a specific method for the extraction and quantification of maize phenolic compounds by ultra-high-pressure liquid chromatography-tandem multiple reaction monitoring mass spectrometry (UHPLC-MRM-MS/MS) analysis. We provide detailed instructions for the extraction of phenolics using acidic methanol, and for the quantification of 33 different compounds in maize stems, including flavonoids, phenolic acids, and lignin precursors.

Extraction and Quantification of Total Anthocyanins, Determination of Anthocyanidin Core Structures, and Characterization of Specific Anthocyanins from Maize.

Anthocyanins are flavonoid pigments that accumulate in fruits and flowers that serve as attractants for pollinators and seed-dispersing organisms. Anthocyanins exhibit diverse chemical structures, characterized both by different anthocyanidin core structures and numerous chemical modifications of the anthocyanidin core. Here, we describe a protocol for the extraction and quantification of total anthocyanins, as well as for the characterization of anthocyanidin core structures and specific anthocyanins, using a spectrophotometer, high-performance liquid chromatography (HPLC), and ultra-high-performance liquid chromatography-two-dimensional mass spectrometry (UHPLC-MS/MS). The method involves anthocyanin extraction using acidic methanol, anthocyanin quantification using a spectrophotometer, determination of anthocyanidin core structure from hydrolyzed anthocyanin extracts using UHPLC-MS/MS, separation of different anthocyanins using HPLC, and characterization of specific anthocyanins using UHPLC-MS/MS. As an example, we describe how we have used this protocol to extract and quantify total anthocyanins from maize leaves, identify cyanidin as the core anthocyanidin structure, and characterize three specific anthocyanins that accumulate in maize leaves, each having a cyanidin core with decorations of a hexose group, and a malonyl or coumaroyl moiety.

Characterization of the Bioavailability of Per- and Polyfluoroalkyl Substances in Farmland Soils and the Factors Impacting Their Translocation to Edible Plant Tissues.

In this study, various crops and farmland soils were collected from the Fen-Wei Plain, China, to investigate the bioavailability of perfluoroalkyl substances (PFAS), their accumulation in edible plant tissues, and the factors impacting their accumulation. PFAS were frequently detected in all of the crops, with total concentrations ranging from 0.61 to 35.8 ng/g. The results of sequential extractions with water, basic methanol, and acidic methanol indicate that water extraction enables to characterize the bioavailability of PFAS in soil to edible plant tissues more accurately, especially for the shorter-chain homologues. The bioavailability of PFAS was remarkably enhanced in the rhizosphere (RS) soil, with the strongest effect observed for leafy vegetables. The water-extracted Σ16PFAS in RS soil was strongly correlated with the content of dissolved organic carbon in the soil. Tannins and lignin, identified as the main components of plant root exudates by Fourier transform-ion cyclotron resonance mass spectrometry, were found to enhance the bioavailability of PFAS significantly. Redundancy analysis provided strong evidence that the lipid and protein contents in edible plant tissues play important roles in the accumulation of short- and long-chain PFAS, respectively. Additionally, the high water demand of these tissues during the growth stage greatly facilitated the translocation of PFAS, particularly for the short-chain homologues and perfluorooctanoic acid.

In Situ ATR-FTIR Studies on the β-Sheet Formation of Native and Regenerated Bombyx mori Silk Material in Solution and Its Potential for Drug Releasing Coatings.

Dynamic attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy at both solutions and coatings of a semicrystalline silk material derived from Bombyx mori was applied to monitor the β-sheet conformation, which is known to correlate with silk protein crystallinity. The secondary structure-sensitive Amide I band was analyzed. Two silk protein samples were studied: native-based silk buffer fibroin (NSF) was extracted from silk glands and regenerated silk fibroin (RSF) was extracted from degummed cocoons. Solutions of both NSF and RSF at 2 mg/mL featured low initial β-sheet contents of 5-12%, which further increased to 47-53% after 24 h. RSF and NSF solutions at 23 mg/mL also featured low initial β-sheet contents of 9-10%, which yet only slightly increased to 16-17% after 24 h. Coatings deposited from RSF solutions showed high surface integrity (Q > 99%) after rinsing in mineralized water, enabling interfacial drug delivery applications. RSF coatings were post-treated with either formic acid (FA) or pure methanol (MeOH) vapor to showcase inducibility of crystalline domains in RSF coatings. Such coatings were loaded with the model antibiotic drugs tetracycline (TCL) and streptomycin (STRP), and the sustained release of TCL was followed in contact with (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) (HEPES) buffer. RSF/TCL coatings post-treated with formic acid (FA) vapor followed by methanol (MeOH) vapor showed a significantly lower (52%) initial burst of rather hydrophobic TCL compared to untreated RSF/TCL coatings (72%), while no such significant release difference was observed for hydrophilic STRP. This was rationalized by a specific interaction between nonpolar TCL and hydrophobic crystalline RSF domains.

Chemoreactive 2,5-Diketopiperazines from a Penicillium sp., Structure Revision of Reported Analogues and Proposed Facile Transformation Pathways.

Merkel cell carcinoma (MCC) is a rare and aggressive cutaneous cancer. Two new prenylated indole 2,5-diketopiperazine alkaloids, brevianamides E1 (1) and E2 (2), were isolated from a Penicillium fungus. Both compounds showed moderate cytotoxic activity against select MCC cell lines (i.e., MCC13, MKL-1, UISO, and WaGa) in the low micromolar range. The relative and absolute configurations of 1 and 2 were determined by combined approaches, including NOESY spectroscopy, DFT ECD and DP4 plus calculations, and Marfey's reaction. Literature research and the comparison of NMR and ECD data led to the structure revision of three previously reported natural analogues, notoamides K and P and asperversiamide L. The structurally unstable 1 and 2 underwent steady interconversion under neutral aqueous conditions. Investigation of the degradation of 2 in acidic methanol solutions led to the identification of a new methoxylated derivative (6) and two new ring-opened products (7 and 8) with the rearranged, elongated, 4-methylpent-3-ene side chain. The facile transformation of 2 to 7 and 8 was promoted by the intrinsic impurity (i.e., formaldehyde) of HPLC-grade methanol through the aza-Cope rearrangement.

In situ preparation of MOF-74 for compact zincophilic surfaces enhancing the stability of aqueous zinc-ion battery anodes

Zinc-ion batteries (ZIBs), while celebrated for their environmental friendliness, abundant material availability, and inherent safety, face significant challenges that curtail their performance and lifecycle. These challenges include the formation of zinc dendrites, susceptibility to electrolyte corrosion, and the propensity for hydrogen evolution reactions. Addressing these critical issues, our research introduces an innovative surface modification strategy for zinc anode of ZIB with mild electrolyte, by the in-situ synthesis of Metal-Organic Framework (MOF-74) facilitated by the mild acidity of a 2,5-dihydroxyterephthalic acid (DHTA) methanol solution. The zincophilic sites and pore structure introduced by MOF-74 to substantially enhance the surface properties of zinc anodes and accelerate the solvation process, enabling uniform zinc deposition, inhibiting dendrite growth, and significantly bolstering corrosion resistance and electrochemical stability. Combination of physical and electrochemical characterization techniques are employed to validate the successful implementation of MOF-74 on the zinc anode surface and its resultant benefits. When tested in full cell setups with α-MnO2 as the cathode, the MOF-74 modified zinc anodes displayed exceptional cyclic stability and rate performance, surpassing those of unmodified counterparts. This investigation highlights the potential of MOF materials to address the electrochemical challenges facing zinc anodes, offering a straightforward yet efficacious strategy to enhance the performance and longevity of ZIBs.

Determination and Identification of Antibiotic Residues in Fruits Using Liquid Chromatography-High-Resolution Mass Spectrometry (LC-HRMS).

Antibiotic residues may be present in fruit products from trees that were treated to combat bacterial diseases such as citrus greening or blight. A liquid chromatography-high-resolution mass spectrometry (LC-HRMS) method was developed for the simultaneous determination and identification of streptomycin, kasugamycin, penicillin, and oxytetracycline residues in fruit. Samples were extracted with acidic methanol and separation was optimized for a hydrophilic interaction LC column. A Q-Exactive HRMS instrument was used to obtain product ion spectra for analyte identification. Quantitation was performed with matrix-extracted calibration curves and internal standard correction. The method was tested on many different types of fruit. In general, fortified samples demonstrated acceptable recoveries (82-116%) and reproducibility (<15% RSD). Method detection limits for these analytes were well below the established US EPA tolerance levels. It was also possible to analyze the fruit extracts prepared using this method for additional chemical contaminants using LC-HRMS.

Constructing Gradient Orbital Coupling to Induce Reactive Metal-Support Interaction in Pt-Carbide Electrocatalysts for Efficient Methanol Oxidation.

Reactive metal-support interaction (RMSI) is an emerging way to regulate the catalytic performance for supported metal catalysts. However, the induction of RMSI by the thermal reduction is often accompanied by the encapsulation effect on metals, which limits the mechanism research and applications of RMSI. In this work, a gradient orbital coupling construction strategy was successfully developed to induce RMSI in Pt-carbide system without a reductant, leading to the formation of L12-PtxM-MCy (M = Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W) intermetallic electrocatalysts. Density functional theory (DFT) calculations suggest that the gradient coupling of the d(M)-2p(C)-5d(Pt) orbital would induce the electron transfer from M to C covalent bonds to Pt NPs, which facilitates the formation of C vacancy (Cv) and the subsequent M migration (occurrence of RMSI). Moreover, the good correlation between the formation energy of Cv and the onset temperature of RMSI in Pt-MCx systems proves the key role of nonmetallic atomic vacancy formation for inducing RMSI. The developed L12-Pt3Ti-TiC catalyst exhibits excellent acidic methanol oxidation reaction activity, with mass activity of 2.36 A mgPt-1 in half-cell and a peak power density of 187.9 mW mgPt-1 in a direct methanol fuel cell, which is one of the best catalysts ever reported. DFT calculations reveal that L12-Pt3Ti-TiC favorably weakens *CO absorption compared to Pt-TiC due to the change of the absorption site from Pt to Ti, which accounts for the enhanced MOR performance.

In-gel protein digestion using acidic methanol produces a highly selective methylation of glutamic acid residues

Mass-tolerant open search methods allow the high-throughput analysis of modified peptides by mass spectrometry. These techniques have paved the way to unbiased analysis of post-translational modifications in biological contexts, as well as of chemical modifications produced during the manipulation of protein samples. In this work, we have analyzed in-depth a wide variety of samples of different biological origin, including cells, extracellular vesicles, secretomes, centrosomes and tissue preparations, using Comet-ReCom, a recently improved version of the open search engine Comet-PTM. Our results demonstrate that glutamic acid residues undergo intensive methyl esterification when protein digestion is performed using in-gel techniques, but not using gel-free approaches. This effect was highly specific to Glu and was not found for other methylable residues such as Asp.

Examining dietary supplements containing Euterpe oleracea Mart. (açaí) for potential botanical-drug interactions involving CYP3A4 inhibition

BackgroundBotanical dietary supplements (BDS) are consumed more by cancer patients than otherwise healthier patients to alleviate side effects of chemotherapy drugs or increase quality of life. The enzyme responsible for the metabolism of most anticancer drugs is CYP3A4, an enzyme predominantly located in the liver. HypothesisOur research team examined the potential risk between CYP3A4-interactive cancer drugs and Euterpe oleracea Mart. (açaí) berry and found that the compounds that passively and non-passively diffused from methanol açaí extract displayed significant inhibition of liver CYP3A4 – suggesting the potential for interactions between açaí and drugs metabolized by CYP3A4 if used synchronously. This study aims to identify the compounds responsible for the CYP3A4 inhibition using the newly automated Bioactivity – Global Natural Product Social Molecular Networking (GNPS) tool. MethodsDietary supplement capsules from two manufacturers (F1 and F2) containing aqueous extracts of açaí fruits were extracted separately by methanol (ME) and acidic methanol (AC) and standardized to cyanidin-3-O-glucoside (CG) concentration at a human-relevant dose. After solvent removal, a parallel artificial membrane permeability assay (PAMPA) was utilized to filter intestinal passive diffusion of the four extract constituents so that compounds could be tested for inhibition of hepatic CYP3A4. Passively and non-passively diffused constituents of extracts from PAMPA assays were injected into the liquid chromatography-mass spectrometry (LC–MS) and characterized for visualization and comparison of chemical entities. To elucidate the non-passively diffused compounds responsible for significant CYP3A4 inhibition, the Bioactivity – GNPS tool was used to hypothesize which compounds within the formulation extract were potentially active to accelerate their identification. ResultsThere was no significant inhibition of CYP3A4 by passively diffused constituents for any extract. There was, however, significant inhibition by non-passively diffused constituents of both F1ME and F1AC extracts with 50 % CYP3A4 inhibition at the donor compartment concentrations 5.764 and 15.58 ng/ml CG, respectively. Six compounds were predicted to be inhibitors of CYP3A4 from methanol F1 extract, including betaine and 5 unknown compounds. ConclusionThis indicates that BDS containing açaí may not inhibit CYP3A4 through passively diffused compounds. Compounds from açaí BDS that inhibit CYP3A4 may be absorbed through other mechanisms, such as transporters.

QUANTIFICATION AND QUALITY CONTROL OF TRIPLE-DRUG COMBINATION EMPLOYED FOR GASTRIC ULCER USING STABILITY-INDICATING SELECTIVE RP-HPLC TECHNIQUE

Objective: A seven-day regimen consisting of vonoprazan (VNP), amoxicillin (AXC) and clarithromycin (CRC), administered twice daily, has been permitted and reimbursed by health coverage as initial therapy. No technique has been implemented yet to determine the quantities of VNP, AXC, and CRC combination. This work effectively aimed at estimating these medications (VNP, AXC, and CRC) at the same time by developing an HPLC technique that saves money and time. Methods: The VNP, AXC, and CRC were separated in a “Waters” column (C18 nature; 250 mm sized length; 4.6 mm sized internal diameter; 5 µm sized particle; 25 °C temperature). Phosphoric acid (0.1% in water; pH 4.2) and absolute methanol (50:50, v/v) comprise the mobile phase. The drug product, Voqueznatripak, was subjected to hydrolysis, oxidation, photolysis, and thermal stressors with the intent to cause enforced degradation. The suggested "HPLC conditions" were verified in compliance with ICH guidance. Results: The measurements had a linear range of 10–20 µg/ml for VNP and 250–750 µg/ml for AXC and CRC. The AXC, CRC, and VNP had LOQ’s 5.302 µg/ml, 5.487 µg/ml and 0.523 µg/ml, respectively. Precision measurements were&lt;0.2% RSD and accuracy ranges were 99.40% to 101.46%. The newly devised “HPLC conditions” specificity attribute and stability-indicating quality were also validated by forced degradation tests. Conclusion: The newly devised “HPLC conditions” for analysing AXC, CRC, and VNP in formulation dosage form and stability samples might be adapted by quality control laboratories. The devised “HPLC conditions” is qualified and consistent to reveal and detect any probable change in the drug product assessments throughout stability experiments.

Crystal structure characterization, Hirshfeld surface analysis, and DFT calculation studies of 1-(6-amino-5-nitronaphthalen-2-yl)ethanone

The title compound, C12H10N2O3, was obtained by the deacetylation reaction of 1-(6-amino-5-nitronaphthalen-2-yl)ethanone in a concentrated sulfuric acid methanol solution. The molecule comprises a naphthalene ring system bearing an acetyl group (C-3), an amino group (C-7), and a nitro group (C-8). In the crystal, the molecules are assembled into a two-dimensional network by N...H/H...N and O...H/H...O hydrogen-bonding interactions. n–π and π–π stacking interactions are the dominant interactions in the three-dimensional crystal packing. Hirshfeld surface analysis indicates that the most important contributions are from O...H/H...O (34.9%), H...H (33.7%), and C...H/H...C (11.0%) contacts. The energies of the frontier molecular orbitals were computed using density functional theory (DFT) calculations at the B3LYP-D3BJ/def2-TZVP level of theory and the LUMO–HOMO energy gap of the molecule is 3.765 eV.

Determination of two perfluorinated compounds in urine by liquid chromatography-tandem mass spectrometry

Objective: To establish a method for the determination of two perfluorinated compounds in urine by liquid chromatography-tandem mass spectrometry. Methods: In November 2022, urine samples were extracted by acidic methanol, purified by WAX solid phase extraction column, and eluted with methanol water, then Waters ACQUITY UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm) was used with 1.0 mmol/L ammonium acetate solution and methanol as mobile phase. The gradient elution was carried out, the detection was carried out by electrospray negative ion multiple response monitoring (MRM) mode, and the quantitative method was internal standard method. Results: Perfluorooctanoic acid and perfluorooctane sulfonic acid had a good linear relationship in the concentration range of 0.5-50.0 μg/L, and the correlation coefficient was >0.999. The limit of detection was 0.017 μg/L, and the limit of quantitation was 0.005 μg/L. The average recoveries were 96.3% and 101.8%, respectively. Days of precision were 3.5%-6.2% and 3.1%-7.4%, respectively, daytime precision were 4.3%-6.8% and 4.7%-8.1%, respectively. Conclusion: The established method of liquid chromatography-tandem mass spectrometry is high sensitivity and accuracy, and is suitable for the determination of perfluorooctanoic acid and perfluorooctane sulfonic acid in human urine.