Mixture Of Acetonitrile Research Articles

Strong impact of exposure to water/solvent mixtures on permeance of nanofiltration membranes

Water/solvent mixtures released from industrial processes, especially in pharma and fine chemical synthesis or in advanced oil production, are an environmental concern, necessitating the development of efficient remediation and recycling techniques. Solvent-tolerant nanofiltration (STNF), situated between aqueous nanofiltration (NF) and solvent-resistant nanofiltration (SRNF), offers a promising solution. This study investigates the potential of using aqueous NF- and SRNF-membranes to treat water/solvent mixtures. Commercial membranes (NF270, DuraMem® 300, DuraMem® 200) and a lab-synthesized polyvinylidene fluoride (XL-PVDF NF) membrane were used to treat dimethyl sulfoxide (DMSO), acetonitrile (ACN), Isopropyl alcohol (IPA), or dimethylformamide (DMF) mixtures with water. The addition of 10% DMSO, ACN, IPA, or DMF to water significantly reduced the permeance of these NF-membranes, and an increase in temperature failed to restore the initial permeance. Changes in both viscosity and surface tension of the water/solvent solutions strongly influence the permeance of the NF-membranes. Flory-Huggins and Zimm-Lundberg theories offered an explanation for the phenomenon where solvent clusters form within the dense polymer matrix of NF-membranes upon exposure to water/solvent mixtures, resulting in decreased water permeabilities. NMR analysis identified of the presence of small amounts of solvents in the STNF-membranes, even still after prolonged exposure to pure water permeation. The results emphasize the current shortcomings of aqueous and solvent-resistant membrane chemistries in handling water/solvent mixtures. Minor solvent additions significantly modify NF membrane permeance, emphasizing the need for innovative material design, especially given the variable solvent content in industrial applications.

Simultaneous HPLC determination of remdesivir and dexamethasone in the presence of metformin, sitagliptin, and glimepiride in a synthetic mixture and spiked human plasma

The COVID-19 pandemic has raised many questions regarding the control and therapy of type 2 diabetes and the higher risk of severe disease progression. One of the therapeutic regimens used in moderate and severe cases of COVID-19, endorsed by the World Health Organization, involves the administration of an antiviral medicinal product and a corticosteroid. The present study describes the development of a liquid chromatographic method for the simultaneous separation and quantification of Remdesivir and Dexamethasone in the presence of Metformin, Sitagliptin, and Glimepiride in a synthetic mixture. The developed method also allows determination of Remdesivir, Dexamethasone, and Glimepiride in spiked plasma samples, using Sitagliptin as internal standard. A mixture of acetonitrile and potassium dihydrogen phosphate buffer (pH 3) in a ratio of 45:55 v/v was used as а mobile phase on a C18 column. The recovery percentages from plasma ranged from 85.1 to 108.5%. The developed method can serve in routine quality control and clinical laboratory practice.

Extraction of naturally occurring peptides versus the tryptic digestion of proteins from fetal versus adult bovine serum for LC-ESI-MS/MS

The naturally occurring peptides and digested proteins of fetal versus adult bovine serum were compared by LC-ESI-MS/MS after correction against noise from blank injections and random MS/MS spectra as statistical controls. Serum peptides were extracted by differential precipitation with mixtures of acetonitrile and water. Serum proteins were separated by partition chromatography over quaternary amine resin followed by tryptic digestion. The rigorous X!TANDEM goodness of fit algorithm that has a low error rate as demonstrated by low FDR q-values (q ≤ 0.01) showed qualitative and quantitative agreement with the SEQUEST cross correlation algorithm on 12,052 protein gene symbols. Tryptic digestion provided a quantitative identification of the serum proteins where observation frequency reflected known high abundance. In contrast, the naturally occurring peptides reflected the cleavage of common serum proteins such as C4A, C3, FGB, HPX, A2M but also proteins in lower concentration such as F13A1, IK, collagens and protocadherins. Proteins associated with cellular growth and development such as actins (ACT), ribosomal proteins like Ribosomal protein S6 (RPS6), synthetic enzymes and extracellular matrix factors were enriched in fetal calf serum. In contrast to the large literature from cord blood, IgG light chains were absent from fetal serum as observed by LC-ESI-MS/MS and confirmed by ELISA.

Development and validation of a simple and efficient method for the analysis of commercial formulations containing clopyralid, picloram and aminopyralid as active ingredients

Liquid chromatography plays a pivotal role in evaluating pesticide formulations as it enables the determination of multiple active substances in plant protection products. An adaptable separation technique has been developed, enabling the qualitative and quantitative analysis of clopyralid, picloram, and aminopyralid within pesticide formulations in line with SANCO/3030/99 rev. 5 guidelines. This article offers an insight into the validation procedure encompassing key aspects such as selectivity, linearity, accuracy, precision, and recovery. It places emphasis on critical stages, including sample preparation, chromatographic separation, detection, quantification, and data analysis. The active ingredients are separated using chromatography with isocratic elution, utilizing a mobile phase consisting of a mixture of water, acetonitrile, and acetic acid in a specific ratio (83:15:2 v/v/v). This separation is carried out on a YMC-Pack ODS-AQ column (250 mm x 4.6 mm, 5 μm) at a flow rate of 1.5 mL/min. The method’s validation parameters have produced satisfactory outcomes. The recovery rates for each individual compound were found to be in the range of 98.6% to 101.0%. Precision, as indicated by the relative standard deviation (%RSD), was lower than the values predicted by the modified Horwitz equation. Furthermore, the correlation coefficients assessing the linearity of the response exceeded 0.99.

A green perspective on simultaneous HPLC and UV spectrophotometric estimation of Udenafil and Dapoxetine hydrochloride in pharmaceutical formulations

Clinical research has affirmed that the combination of Udenafil and Dapoxetine hydrochloride yields greater improvement in erectile dysfunction compared to the use of individual medications. There is a requirement of precise quantitative method for accurate determination of Udenafil and Dapoxetine when taken together. Consequently, our interest lies in developing and validating analytical methods for the simultaneous estimation of Udenafil and Dapoxetine - Various strategies, such as UV spectrophotometric approaches and an innovative, straightforward, accurate, sensitive, and robust High-Performance Liquid Chromatography (HPLC) procedure, have been explored. An Isocratic HPLC approach was employed using reversed-phase CHEMSIL ODS C18 column (4.6 mm x 250 mm, 5 µm) as a stationary phase and detection wavelength (λ max) 230 nm for the two analytes in the chromatographic column. The mobile phase comprised of (70:30, v/v) mixture of Acetonitrile and 10 mM Ammonium formate buffer having pH 5, adjusted with formic acid. The elution was carried out at a constant flow rate of 1 mL/min. The UV simultaneous equation technique estimated the medicine's quantities and derived a simultaneous equation for DAP and UDN using 2 wavelengths, 230 nm and 298 nm. Furthermore, the two advanced methods underwent rigorous statistical validation, guided by the valuable ICH Q2R1 guidelines, affirming their effectiveness as a successful analytical tool for the concurrent analysis of both tablets in bulk and the synthetic mixture fabricated in the laboratory. To assess the environmental impact of contemporary UV spectrophotometric and HPLC techniques, the Green Analytical Greenness Metric (AGREE) software and the Green Analytical System Index (GAPI) were employed to evaluate the greenness profile. This examination confirmed the method's environmental friendliness concerning solvent usage, chemical ingredients, energy consumption, and waste production. The developed UV method is more sustainable and greener compare to HPLC method for simultaneous estimation of compound, which can be utilised by industry for quantification of each individual drug in their combination products.

Stability Indicating Method Development and Validation for the Estimation of Bempedoic Acid by RP-HPLC.

Bempedoic acid (BEM) belongs to a category of drugs known as Adenosine triphosphate-citrate Lyase (ACL) inhibitors. It is a prodrug with intracellular activation that is administered orally. Bempedoic acid is used to treat existing atherosclerotic cardiovascular diseases, mainly hypercholesterolemia. For the stability-indicating assay, the HPLC method was employed using a Kromasil 100-5-C8 column (100 mm × 4.6 mm), a UV detector set at 230 nm, and a mobile phase comprising a 70:30 v/v mixture of acetonitrile and 0.1% Orthophosphoric Acid (OPA) buffer. The method was operated at an ambient temperature with a flow rate of 1 mL/min. The method developed has been statistically validated according to ICH guidelines. The stability-indicating method was executed using a Kromasil 100-5-C8 (100 mm × 4.6 mm) column at a 1.0 mL/min flow rate. A mixture of acetonitrile and 0.1% Orthophosphoric Acid (OPA) buffer in a 70:30 v/v ratio made up the mobile phase. BEM's retention times were discovered to be 1.88 minutes each. The temperature was kept at room temperature. 234 nm was the ideal wavelength for BEM. According to ICH criteria, the approach developed has undergone statistical validation. BEM's % RSD was discovered to be 0.6, respectively. For BEM, the % recovery was determined to be 100.0%. Regression models for bempedoic acid yielded LoD and LoQ values of 3.3 and 10.1 g/mL, respectively. The method showed good reproducibility and recovery with a % RSD less than 2. Studies on forced degradation confirmed the method's capacity to indicate stability in the presence of stress conditions, such as acid, basic, peroxide, UV, heat, and humidity. Both the retention times and the run time were shortened. In accordance with ICH Q2 (R1) guidelines, this method was successfully tested with HPLC to confirm the chemical structures of newly produced degradation products of bempedoic acid.

Simultaneous determination of sulfonamides, trimethoprim, amoxicillin and tylosin in medicated feed by high performance liquid chromatography with mass spectrometry.

The article presents a rapid and simple analytical procedure for determination of four sulfonamides (sulfadiazine, sulfamerazine, sulfamethazine and sulfamethoxazole), trimethoprim, tylosin and amoxicillin in animal medicated feed. Eighteen medicated feed samples were analysed for active substances. The analytical protocol used a mixture of acetonitrile and 0.05 M phosphoric buffer, pH 4.5 for the extraction of seven antibacterial substances. After extraction, the samples were diluted in Milli-Q water and analysed by liquid chromatography with mass spectrometry. The developed procedure was subjected to validation in terms of linearity, selectivity, limits of quantification and determination, repeatability, reproducibility and uncertainty. The validation of the method was carried out in accordance with the criteria set out in Commission Implementing Regulation (EU) 2021/808 and ICH guidelines. This method provided average recoveries of 90.8 to 104.5% with coefficients of variation for repeatability and reproducibility in the ranges of 3.2-6.9% and 5.2-8.3%, respectively for all analysed antibacterial substances. The limit of detection and limit of quantification for all seven analytes ranged from 5.4 mg/kg to 48.3 mg/kg and from 10.4 mg/kg to 119.3 mg/kg, respectively. The uncertainty of the method depending on the compound varied from 14.0% to 24.0%. The validated method was successfully applied to the 18 medicated feeds. The developed method can be successfully used to routinely control the content and homogeneity of seven antibacterial substances in medicated feed.

Trace level quantification of N-nitrosorasagiline in rasagiline tablets by LC-TQ-MS/MS

Parkinson's disease is a chronic, progressive neurological disease that currently affects about more than 10 million population worldwide. Rasagiline is a selective, irreversible monoamine oxidase type B inhibitor used as monotherapy in early Parkinson's disease. Rasagiline tablets have been recalled from market due to the presence of unacceptable levels of nitrosamine impurity. European Medical Agency has set up very stringent limit 100ng/day of N-nitrosorasagiline (NSRG) in drug product based on its mutagenicity. The analytical methods need to be sufficiently sensitive in order to adequately detect and quantify trace levels of NSRG. A highly sensitive LC-MS/MS method for determination of NSRG in rasagiline tablet formulation was developed by effectively separating on zorbax eclipse XDB C18 column using 0.1% formic acid in mixture of water and acetonitrile (35:65 v/v) in an isocratic mode at 0.5mL/min flow rate. The measurement of NSRG was performed using triple quadrupole mass detection accompanied by electrospray ionization in the multiple reaction monitoring mode. The validation of the method was comprehensive, demonstrating strong linearity across the concentration spectrum of 2 to 200ng/mL for NSRG. The obtained correlation coefficient exceeded 0.998, signifying a robust relationship. Recoveries spanning from 80.0% to 120.0% for NSRG were deemed satisfactory. The developed method was able to detect and quantitate NSRG at a concentration level of 1 to 2ng/mL respectively (1 to 2ppm with respect to 1mg/mL of rasagiline tablet sample concentration). The developed and validated method can be employed for routine quality control testing of rasagiline tablets.

Combined thermodynamic and theoretical study on ether-functionalized ionic liquid mixture systems of [MOEmim][TFSI] with ACN/GBL

Ether-functionalized ionic liquids (ILs) have a higher fluidity and are widely used in a variety of applications due to the introduction of the ether group. In order to better understand the relationship between properties and internal interactions of ether-based ILs, we prepared two ether-functionalized ILs 1–2-methoxyethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide ([MOEmim][TFSI]) with acetonitrile (ACN) or γ-butyrolactone (GBL) mixture systems, and investigated the changes of their thermodynamic properties and internal interaction behaviors over the entire concentration range. First, the thermodynamic properties such as dynamic viscosity, density and electrical conductivity of the two mixture systems were measured from 288.15 K to 343.15 K. The excess molar volume (VE), and viscosity deviation (Δη) were calculated by using the measured experimental density and dynamic viscosity data, which can provide microscopic information on the interactions. Further, the intermolecular interactions of the mixture systems were evaluated by density functional theory (DFT) calculations. The sigma–profile (σ–profile) provided insight into the hydrogen bonds (H-bonds) and molecular surfaces interactions. We also used molecular dynamics simulations (MD) to study ILs mixtures in many different solvent concentrations, thereby providing a microscopic and macroscopic characterization of fluid structure, molecular aggregation, and intermolecular forces.

Development and Validation of RP-HPLC Method using UV detection for Simultaneous quantification of Amlodipine besylate and Nebivolol hydrochloride in Fixed-dose combination tablets

Calcium channel blockers and beta blockers are the class of choice of drugs in treatment of hypertension and cardio vascular diseases. Such a fixed dose combination is viable to deal with the patients for whom monotherapy is not sufficient. A simple, responsive and productive high performance liquid chromatography method was designed and approved for simultaneous quantification of Amlodipine Besylate (AMB) and Nebivolol Hydrochloride (NBL) in tablet dosage form. In the developed method mobile phase comprised of a mixture of aqueous buffer (pH 6) and acetonitrile (55:45 v/v, respectively) at a flow rate of 1.5 ml/min. Chromatographic separation was achieved using Reverse-phase Kromasil 60-5-CN column, 250 × 4.6 mm (particle size 5 μm). Method was discovered specific as no obstruction of excipients peaks at the retention time of tablets was observed and demonstrated linearity in concentration range of 30.4-70.8 mcg/ml for AMB and 29.8-69.4 mcg/ml for NBL with R2> 0.999. Accuracy values for AMB and NBL was found to be 98.21-99.49% and 97.91-99.09%, respectively. Inter-day and intra-day precision was carried out and % RSD was found to be less than 2%. Robustness was performed to evaluate the results with slight variations in method and % RSD found to be less than 2%. Solution stability studies were conducted in normal conditions. Force degradation study was carried out using Photo-diode Array (PDA) detector and revealed that acid degradation in AMB and NBL was 7.12% and 1.88%, alkaline degradation was 9.61% and 0.05% and oxidative degradation was 8.50% and 1.59%, respectively.

Synthesis and Trace-Level Quantification of Mutagenic and Cohort-of-Concern Ciprofloxacin Nitroso Drug Substance-Related Impurities (NDSRIs) and Other Nitroso Impurities Using UPLC-ESI-MS/MS-Method Optimization Using I-Optimal Mixture Design.

Globally, the pharmaceutical industry has been facing challenges from nitroso drug substance-related impurities (NDSRIs). In the current study, we synthesized and developed a rapid new UPLC-MS/MS method for the trace-level quantification of ciprofloxacin NDSRIs and a couple of N-nitroso impurities simultaneously. (Q)-SAR methodology was employed to assess and categorize the genotoxicity of all ciprofloxacin N-nitroso impurities. The projected results were positive, and the cohort of concern (CoC) for all three N-nitroso impurities indicates potential genotoxicity. AQbD-driven I-optimal mixture design was used to optimize the mixture of solvents in the method. The chromatographic resolution was accomplished using an Agilent Poroshell 120 Aq-C18 column (150 mm × 4.6 mm, 2.7 μm) in isocratic elution mode with 0.1% formic acid in a mixture of water, acetonitrile, and methanol in the ratio of 475:500:25 v/v/v at a flow rate of 0.5 mL/min. Quantification was carried out using triple quadrupole mass detection with electrospray ionization (ESI) in a multiple reaction monitoring technique. The finalized method was validated successfully, affording ICH guidelines. All N-nitroso impurities revealed excellent linearity over the concentration range of 0.00125-0.0250 ppm. The Pearson correlation coefficient of each N-nitroso impurity was >0.999. The method accuracy recoveries ranged from 93.98 to 108.08% for the aforementioned N-nitrosamine impurities. Furthermore, the method was effectively applied to quantify N-nitrosamine impurities simultaneously in commercially available formulated samples, with its efficiency recurring at trace levels. Thus, the current method is capable of determining the trace levels of three N-nitroso ciprofloxacin impurities simultaneously from the marketed tablet dosage forms for commercial release and stability testing.

Pharmacokinetic analysis of febuxostat in human serum by UFLC based on fluorimetric derivatization

An ultra fast liquid chromatographic (UFLC) method using fluorimetric detection for the quantitation of Febuxostat (FEB) in human serum was developed by precolumn derivatization with 4-bromomethyl-7-methoxy coumarin (BrMmC). The derivatization was catalyzed with dibenzo-18-crown-6-ether to produce a fluorescent derivative which was determined through fluorescence measurement with excitation at 320 nm and emission at 395 nm wavelengths. A C18 column with 100 cm x 4.6 mm, 3 µm particule size was used for the UFLC separation procedure. A mixture of acetonitrile: methanol: 0.05 M aqueous ammonium acetate (pH 5.0) (40:40:20, v/v/v) was used as mobile phase. During the procedure, the flow rate was maintained at 0.5 mL/min. A calibration curve was then plotted as 0.005–3.0 µg/mL with a detection limit of 0.0022 µg/mL and quantification limit of 0.0073 µg/mL. The mean recovery to reveal the accuracy and relative standard deviation (RSD) that indicates the precision of the method were found out to be 85.20 % and less than 3.52 %, respectively. The utility of the new method has been demonstrated by measuring the pharmacokinetics of FEB by administration of 80 mg tablets to a healthy female volunteer, aged 42.

Structural characterization of a new samarium–sodium heterometallic coordination polymer

Lanthanide-containing materials are of interest in the field of crystal engineering because of their unique properties and distinct structure types. In this context, a new samarium–sodium heterometallic coordination polymer, poly[tetrakis(μ2-2-formyl-6-methoxyphenolato)samarium(III)sodium(I)], {[SmNa(C8H7O3)4]·solvent} n (Sm-1), was synthesized and crystallized via slow evaporation from a mixture of ethanol and acetonitrile. The compound features alternating SmIII and NaI ions, which are linked by ortho-vanillin (o-vanillin) ligands to form a mono-periodic chain-like coordination polymer. The chains propagate along the [001] direction. Residual electron density of disordered solvent molecules in the void space could not be reasonably modeled, thus the SQUEEZE function was applied. The structural, vibrational, and optical properties are reported.

Determination of ω-end functionalities in tailored poly(2-alkyl-2-oxazoline)s by liquid chromatography and mass spectrometry.

The in-depth analytical characterization of polymers, in particular regarding intended biomedical applications, is becoming increasingly important to elucidate their structure-property relationships. Specifically, end group analysis of e.g. polymers featuring a 'stealth effect' towards the immune system is of particular importance because of their use in coupling reactions to bioactive compounds. Herein, we established a liquid chromatography (LC) protocol to analyse bicyclo[6.1.0]nonyne-functionalized poly(2-alkyl-2-oxazoline)s (POx)s as promising functional polymers that can be applied in strain-promoted click reactions. This work involved the synthesis of poly(2-methyl-2-oxazoline) (PMeOx) and poly(2-ethyl-2-oxazoline) (PEtOx) by living cationic ring-opening polymerization (CROP) with different molar masses ranging from 2 up to 17.5 kDa and, to our knowledge, the first liquid chromatographic analysis of PMeOx. The developed analytical protocol enables the quantitative determination of post-polymerization reaction sequences with respect to the conversion of the ω-end groups. All synthesized polymers were straightforwardly analysed on a C18-derivatized silica monolithic column under reversed-phase chromatographic conditions with a binary mobile phase gradient comprising a mixture of acetonitrile and water. Subsequent mass spectrometry of collected elution fractions enabled the confirmation of the desired ω-end group functionalities and the identification of synthetic by-products.

Laboratory Analogs of Thermally Processed Ices Containing H2O, N2, NH3, CO2, and C2H3N Relevant to Astrophysical Environments

Introduction: Laboratory simulations can benefit ground- and space-based observations of icy bodies in outer space. It is well-known that NH3 and CO2 can interact, forming ammonium carbamate (CH6N2O2). Method: This study examines NH3 and CO2 in thermally processed H2O-rich ices in the laboratory via mid-infrared absorption spectroscopy. In particular, the presence of CO2 in NH3- ice mixtures thermally annealed at 150 K for more than four hours in systematic experiments suggested that ammonium carbamate could potentially trap volatiles within the ice matrix. Result: Additional studies with acetonitrile (C2H3N) in ice mixtures containing H2O, CO2, and NH3 were also performed. Absorption peak position changes were recorded when the temperature was slowly increased (≤ 5K/min) and also annealed at temperatures up to 150 K. Conclusion: These studies will hopefully be useful in interpreting pre-biotic chemistry in the Solar System.

Coordinating nature of M6L12 double-stranded macrocycles: co-ligand competition of perchlorate, water, and acetonitrile depending on metal(II) ions.

Self-assembly of M(ClO4)2 (M(II) = Mn(II), Co(II), Ni(II), Cu(II), and Zn(II)) with dicyclopentyldi(pyridine-3-yl)silane (L) as a donor in a mixture of acetonitrile and toluene produces crystals consisting of M6L12 double-stranded macrocycles. The geometry around the M(II) cations is a typical octahedral arrangement, but the metallamacrocycles' outer axial coordination environment is sensitive to the M(II) cations. The conformation of the unique metallamacrocycles is informatively dependent on the nature of the coordination around the M(II) cations via subtle co-ligand competition among perchlorate anions, water, and acetonitrile. Both the coordinated acetonitriles and the solvate molecules of the crystals are removed at 170 °C, thereby transforming the crystals into new crystals that return to their original form in the mixture of toluene and acetonitrile. Catalytic oxidation of 3,5-di-tert-butylcatechol using [Cu6(ClO4)8(CH3CN)4L12]4ClO4·5C7H8 is much faster than those using the transformed product, [Cu(ClO4)2L2], and a simple mixture of Cu(ClO4)2 + L.

Enhanced Detection of Benzo[a]pyrene in Olive Oil through Low Temperature Liquid-Liquid Extraction Coupled with Constant Energy Synchronous Fluorescence Spectroscopy

Refined processed olive oil can indeed become significantly contaminated with polycyclic aromatic hydrocarbons (PAHs). To assess exposure to these contaminants, benzo[a]pyrene (B[a]P) is utilized as a marker due to its known carcinogenicity in humans. The European Commission has established a maximum limit of 2 μg kg-1 for B[a]P in edible oils. However, the analysis of trace amounts of B[a]P in a complex matrix like olive oil poses a persistent challenge. In this study, we have developed a low-temperature liquid-liquid extraction method in combination with constant energy synchronous fluorescence analysis for the determination of B[a]P in olive oil samples. The analyte was extracted from the olive oil using a mixture of acetonitrile and acetone. The performance of fluorescence measurements was evaluated by carefully considering the effects of solvent, temperature, acetone quenching, and slit width for monochromators. The proposed method demonstrates a linear range from 0.8 to 3.2 μg kg-1, with limits of detection and quantification of 0.04 and 0.80 μg kg-1, respectively. Precision and trueness assessments revealed relative standard deviations of less than 10% and recovery rates ranging from 103 to 112%. This method presents an efficient and rapid alternative to sample preparation procedure that minimizes organic solvent consumption.

Direct sulfur-containing compound speciation in crude oils and high-boiling fractions by APCI (+) FT-ICR mass spectrometry.

In this study, we focus on advancing the methodology for detecting sulfur-containing compounds (SCCs) in crude oils and their derivatives. These compounds are critical for geochemical analysis, crude oil evaluation, and overcoming production and refining challenges. Although various analytical techniques exist, the precision and resolution power of Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) stand out. However, the current methods for characterizing SCCs in petroleum products often lack standardization and tend to be complex and time-consuming. Our research introduces the use of Atmospheric Pressure Chemical Ionization (APCI) as an efficient alternative. We employed a mixture of toluene and methanol (1 : 1 ratio) for APCI, which demonstrated superior performance in sulfur speciation compared to mixtures of toluene and acetonitrile. Our specified method showed high repeatability, with coefficients of variation reported between 5% and 14%. This method effectively covers a wide range of double bond equivalents (DBEs) from 1 to 25 and various carbon numbers, demonstrating notable repeatability and reproducibility. Compared to results from ESI post-S-methylation and Atmospheric Pressure Photoionization (APPI), APCI offers a more comprehensive analysis of sulfur compounds, presenting a broad spectrum of molecular formulae and extending across a vast range of carbon numbers and DBEs. Here, we demonstrate that APCI is a robust and efficient method for direct and extensive sulfur speciation in crude oil and its high-boiling fractions, marking a significant advancement over existing techniques. This methodological improvement opens new pathways for more accurate and efficient sulfur compound analysis in petroleum products.

Construction and catalytic effects of solvent- and metal(ii)-dependent products: the process of transformation of 0D structures into 3D structures

The dimensions of M(ii) complexes are dependent on the solvents or metals(ii) employed, and a transformation of the cage into 3D occurs. Zn(ii) and Cu(ii) species are effective catalysts in transesterification and catechol oxidation, respectively.

Catalyst-free ring opening of azlactones in water microdroplets.

A catalyst-free method was developed for the ring opening of azlactones (also known as oxazolones) in water microdroplets. Azlactone was dissolved in a water : acetonitrile (1 : 1) mixture, and the solution is sprayed by using nitrogen gas at a pressure of 120 psi to generate microdroplets. This method promoted selective cleavage of the lactone bond to afford the corresponding N-benzoyl derivatives in up to 94% isolated yield with no epimerization. Our method produces the ring-opening products in milliseconds (up to 94 μmol for 33.3 minutes), and may have utility for high-throughput synthesis applications.