A magnetic nanosorbent was synthesized from a ferric precursor recovered from iron mining tailings and applied in magnetic solid-phase extraction (MSPE) for the determination of bisphenol A (BPA) in aqueous matrices. An analytical method based on high-performance liquid chromatography with UV detection (HPLC–UV) was developed for the extraction and determination of BPA in water samples. BPA is classified as an emerging contaminant and an endocrine-disrupting compound due to its potential to interfere with the endocrine system. The Fe3O4@SiO2–NH2 nanosorbent was prepared using ferric ions obtained via acid leaching of mining tailings, an abundant industrial waste. The material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), scanning electron microscopy (SEM), transmission electron microscopy (TEM), pH at the point of zero charge (pHPZC), and wettability measurements. The MSPE procedure was optimized by evaluating the elution solvent, sample pH, eluent volume, sample volume, sorbent amount, and stirring time. The method exhibited good linearity (R2 > 0.99), with limits of detection and quantification of 30 and 80 ng mL−1, respectively. Intra- and interday precision and accuracy showed relative standard deviation (RSD) and relative error (RE) values below 15
Imeglimin (IMG) is the first agent of the new tetrahydrotriazine-based class of oral antidiabetic drugs known as ‘glimins’. This work presents LC–ESI–MS based degradation profiling, by fragmentation-assisted structural elucidation of major degradation products of Imeglimin under forced degradation conditions. For that, first we have developed and validated a green, robust, simple and efficient RP-HPLC method to ensure its stability. The column used in the method is ACE CN 25 column (250 mm × 4.6 mm, 5 µm). Acetonitrile: 20 mM Ammonium Formate (60:40
Accurate determination of trace anions in electronic-grade N-methylpyrrolidone (NMP) is crucial for ensuring the reliability of lithium-ion batteries and semiconductor devices. However, severe interference from the massive organic matrix prevents conventional one-dimensional ion chromatography (1D-IC) from meeting the stringent requirements of sub-microgram-per-kilogram (µg/kg) level detection. To address this challenge, an automated, online two-dimensional ion exclusion–ion exchange chromatography (2D-ICE-IC) method integrated with a valve-switching technique was developed. By introducing ion exclusion chromatography (ICE) in the first dimension, the complex NMP matrix and potential interfering components were eliminated, leveraging the distinctly different retention behaviors between the target anions and the organic background. Combined with large-volume injection and a precisely timed valve-switching program, the heart-cut target anions were captured on a concentrator column and subsequently transferred to the second-dimensional ion exchange system for high-sensitivity analysis. Under optimized conditions, five target anions (Cl⁻, Br⁻, NO₃⁻, SO₄²⁻, and PO₄³⁻) exhibited excellent linearity within the range of 0.5–20 µg/kg (r > 0.999), with limits of detection (LODs) as low as 0.006–0.021 µg/kg. Spiked recoveries at low, medium, and high concentration levels ranged stably between 75
Solvents are needed in all branches of chemistry, and they must be eliminated after use. Impurities present in these solvents could concentrate detrimentally during chemical and, especially, pharmaceutical processes. So it is critically important to know the purity of the solvents used. The label-claimed purity of 24 solvents, including polar protic alcohols, polar aprotic carbonate esters and acetonitrile, dipolar ethers, aromatic solvents, and apolar alkanes, was tested by liquid chromatography with fluorescence detection (HPLC-FLD), gas chromatography with flame ionization or mass spectrometry detection (GC-FID or GC–MS). For all 24 tested solvents, the label-indicated purities were confirmed. The study showed that minute amounts of fluorescent impurities could be better visualized on a logarithmic scale of the emitted light rather than on the classical linear scale. Comparing the results obtained for the same solvent by HPLC-FLD and GC-FID showed that the fluorescence detector is so sensitive that it could detect an extremely low concentration of a fluorescent compound that did not produce a signal in the FID detector. However, the FID detected several more impurities than the fluorescence detector since many do not fluoresce. GC-FID and GC–MS chromatograms of the same sample on the same column showed similarities. But the strong advantage of the MS detector is impurity identification using extended modern spectral databases.
A sensitive analytical method was developed and validated for the simultaneous quantification of insulin glargine and its active metabolites M1 and M2 in human K₂EDTA plasma. Plasma sample extraction was performed using an optimized mixed-mode solid-phase extraction (SPE) procedure, followed by analysis using liquid chromatography–tandem mass spectrometry (LC–MS/MS API 6500+) in positive electrospray ionization mode. The method specificity, linearity, sensitivity, recovery, accuracy, precision, IS-normalized matrix factor, matrix effect, and stability, were systematically validated as per ICH M10 guidelines. The method exhibited high specificity, with no significant interference at the retention times of analytes and internal standards. The calibration curves showed linearity over the concentration range of approximately 70–2200 pg/mL, with regression coefficients (r2) ≥ 0.995. The lower limit of quantification was approximately 70 pg/mL for analyte and metabolites. Observed intra-day and inter-day precision (2.93–11.27
In present research, a hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method was proposed for the concurrent determination of 11 biogenic amines, including putrescine (PUT), cadaverine (CAD), histamine (HIS), 2-phenethylamine (2-PHE), tyramine (TYR), spermidine (SPD), octopamine (OA), 5-hydroxytryptamine (5-HT), adrenaline (A), tryptamine (TRP), and spermine (SPM) within 11 min. A Waters ACQUITY UPLC® BEH Amide (100 mm × 2.1 mm i.d., 1.7 μm) was used as stationary phase. Gradient elution was conducted using a mobile phase of 90
The best separation possible of delta-9-tetrahydrocannabinol (Δ9-THC) in complex samples via liquid chromatography (LC) is particularly challenging due to the potential for interference from other cannabinoids. Over 100 cannabinoids have been detected in Cannabis sativa plant samples. The separation of Δ9-THC in Cannabis-derived finished products was believed to be easier than plant extracts to analyze at one time because the acidic cannabinoids are converted to their neutral cannabinoids during material preparation. However, the emergence of synthetic or semi-synthetic cannabinoid products, such as delta-8-tetrahydrocannabinol (Δ8-THC), has led to more chromatographic interferences due to the presence of synthetic by-products. The original LC separation method implemented in the Chemical Sciences Division (CSD) at the National Institute of Standards and Technology (NIST) was not acceptable when these chromatographic interferences were present. Within this context, the work presented here explores initial separation of an 11 cannabinoid mixture using different monomeric and polymeric octadecylsilane (C18) columns via liquid chromatography. These columns were characterized using the Standard Reference Material 869b as a three-component column selectivity test mixture to determine if an LC C18 column is classified as monomeric or polymeric. Monomeric C18 columns (NexLeaf C18, ACE 3 C18, and ACE Super C18) provided better separations of the 11 cannabinoids, and baseline separations were obtained in less than 13 min after minor adjustments to the mobile phase program. Using the NexLeaf C18 LC-UV method, mixtures of Δ9-THC and four known chromatographic interferences were analyzed. Cannabinolic acid (CBNA) could not be separated from Δ9-THC; however, CBNA has drastically different absorbance spectra from Δ9-THC, and the co-elution of these cannabinoids can easily be recognized using photodiode array detection. When CBNA is present, the sample can be reanalyzed using an alternate NexLeaf C18 LC-UV method developed here, which baseline-resolves Δ9-THC and CBNA in 60 min. These two LC-UV methods will be further evaluated at NIST CSD through quantitative comparisons in future publications, enabling their use in the development of reference materials for Cannabis plants and/or Cannabis-derived finished products.
Standardized tuberculosis treatment involves four major drugs: rifampicin, isoniazid, pyrazinamide, and ethambutol. Suboptimal concentrations of these drugs are one of the reasons for treatment failure, relapse, or resistance to the disease, though most patients respond to treatment. It is necessary to monitor the concentrations of these drugs and make the required dose adjustments to achieve the desired therapeutic effect. We developed and validated a simple and practical LC–MS/MS method for the simultaneous estimation of these four main drugs. A single-step protein precipitation technique was employed, using methanol as the precipitating agent to extract the drugs from the plasma sample. Chromatographic separation was achieved on a Phenomenex Luna® C18 column (150 × 4.6 mm, 3 µm) using a mobile phase composed of 0.1
Glatiramer acetate (GA) is a heterogeneous synthetic polypeptide used as a disease-modifying therapy for relapsing forms of multiple sclerosis, and its molecular weight distribution (MWD) is a key attribute for demonstrating lot consistency and comparability across reference and follow-on products. In this work, GA MWD was characterized by size-exclusion chromatography coupled online to multi-angle light scattering and refractive index detection (SEC-MALS-RI), enabling calibration-independent (absolute) molar-mass determination across the elution profile. GA exhibited a broad, asymmetric SEC envelope consistent with inherent compositional and chain-length heterogeneity. Using RI-derived concentration (refractive index increment (dn/dc) established by a linear RI response–concentration relationship with R2 = 1.0000; dn/dc ≈ 0.1834 mL/g, fit error 0.38
This study addresses the issue of hazardous leachables specifically 2-mercaptobenzothiazole and 1,3-diphenylguanidine, which originate from vulcanizing agents and additives in pharmaceutical container materials. These compounds can negatively affect the quality and safety of pharmaceutical products by leaching out within the temperature range of 30–70 °C, which overlaps with typical daily life conditions. We developed a sensitive and robust UHPLC–MS/MS mass spectrometric method for the simultaneous quantification of primary leachables in pharmaceutical container systems. Chromatographic separation was performed on an ACQUITY UPLC CSH C18 column (2.1 × 100 mm, 1.7 µm) using a binary mobile phase consisting of 0.1
This study presents a green, near-solvent-free method for quantifying residual BTEX solvents (benzene, toluene, ethylbenzene, and xylene) in injectable antibiotic vials using gas chromatography with flame ionization detection (GC-FID) coupled with solid-phase microextraction (SPME). Among five fabricated functionalized carbon fibers, the fiber coated with a graphene oxide/pyrrole/aniline nanocomposite (Fiber 4) demonstrated superior adsorption capacity. Optimized extraction parameters were established as follows: fiber length 1.5 cm, sample temperature 50 °C, extraction time 15 min, stirring speed 500 rpm, and 20
The purpose of this study was to study the trace-level quantification of carcinogenic N-nitroso-duloxetine as well as the residual duloxetine HCl in different reactor material cleaning solvent samples. Duloxetine is a serotonin–norepinephrine reuptake inhibitor with a secondary amine group in its structure, which makes it susceptible to nitrosation in the presence of nitrosating agents, favored by low pH conditions. The sensitive LC–HRMS method was developed using an Agilent Poroshell C18 column with an isocratic elution (0.1
This study introduces a novel isocratic ultra-performance liquid chromatography method coupled with photodiode array and electrospray ionization mass spectrometry (ESI/MS) for the quantification of the antifungal drug Posaconazole (PCZ) and its four degradation products in tablet formulations. Employing an innovative Analytical quality by design (AQbD) approach, we established robust chromatographic conditions for precise measurement of degradation impurities resulting from forced degradation processes, such as acid/alkali hydrolysis, peroxide oxidation and thermal/photo degradation. A comprehensive risk assessment was conducted using failure mode effects analysis to identify critical analytical attributes (CAAs) and their impact on analytical target profiles (ATPs). The interactions between the identified CMAs (CMA1—retention time of PCZ and degradant peak; CMA2—resolution between degradant peaks) and ATPs were explored using a Box–Behnken Design (BBD), which led to the selection of optimal chromatographic conditions. These consisted of a mobile phase comprising 20 mM ammonium formate buffer (pH 4.2), acetonitrile, and methanol (70:18:12 v/v/v), an X‑Bridge C18 column (150 × 4.6 mm, 3.5 µm), a detection wavelength of 260 nm, a flow rate of 1.0 mL/min, and an injection volume of 5 µL. Each risk factors were reevaluated, and control on each was relinquished. The validation of the method was performed according to ICH Q2 (R2) guidelines, confirming its specificity, precision, linearity, LOQ, LOD, and accuracy. The developed method was deemed stability-indicating and suitable for routine and stability testing of Posaconazole formulations.
Historically exceptional observations of the blood movement in capillary vessels were revealed by Poiseuille. He found that blood corpuscles in flowing serum undergo only axial movement near the center of the vessels, whereas they rotate near the wall and in the intermediary space. This behavior generated the lift force. Poiseuille’s study of the effect of temperature gradient on the motion of the blood corpuscles resulted in the discovery of thermal diffusion. Recent investigation of the origin of the lift forces, applied on the ring-shaped two-dimensional particles, indicated an important difference between the theoretical and the experimental results and disclosed the necessity to take into account the three-dimensional sphere instead of the ring. The model of creeping flow of the liquid around the spherical particle is proposed to calculate the mean impact forces per unit area induced by the liquid streams in collisions with the surfaces of the upper and lower hemispheres of the particle. The difference of these forces between two hemispheres gives rise to the rotation of the particle and to the consequent lift force. This theoretical model approaches significantly the experimental data, but slightly deviates from them within the whole range of liquid flow velocities. The disaccord is due to the particle’s surface nature which is not smooth. The imperfections of the surface influence the effective particle size because the layer thickness of the species adhering to the surface can depend on the liquid flow velocity. Newton’s iteration method was used to obtain the correction factors. Then the first theoretical data calculation approach was corrected to obtain the second approach which fits almost perfectly the experimental data.
In this study, a non-isothermal chromatographic model is formulated and analyzed by coupling a Tri-Langmuir adsorption isotherm with the Lumped Kinetic Model (LKM). The proposed framework accounts for axial dispersion, finite mass-transfer resistance, and thermal effects arising during adsorption, enabling a more realistic description of the transport and separation of multiple chemical species in a packed chromatographic column. The resulting system of governing equations is solved numerically using the Runge–Kutta Local Discontinuous Galerkin (RK-LDG) method, which is particularly well suited for handling steep concentration and temperature gradients. Different numerical simulations were conducted to examine the effects of temperature, injection conditions, and flow rate as well as multi-site adsorption on chromatographic peaks. It has been shown that the Tri-Langmuir isotherm is a more accurate model of multi-component and nonlinear adsorption than the linear or the Bi-Langmuir model. The objective of this work is that accurate separation of complex mixtures requires careful consideration of both temperature variations and multi-site adsorption effects. Simplified assumptions, such as isothermal operation or single-site binding, can lead to significant deviations in predicted chromatographic behavior. By explicitly accounting for these factors, the proposed model provides a more reliable description of column dynamics and offers a practical framework for improving the design and optimization of chromatographic separation processes in demanding applications.
Artemisia absinthium Linn. (Family: Asteraceae), commonly known as Wormwood, is traditionally used against loss of appetite and mild dyspepsia. Its constituents viz., santonin (sesquiterpene lactone) and α- and β-thujone (monoterpene ketones) exhibit pharmacologic effects such as anthelmintic, neuro-stimulant, antioxidant, etc. They are also reported to exhibit potential toxicity on high or prolonged exposure and thus warrant accurate estimation. The current study aimed to develop a facile and precise method for the simultaneous estimation of santonin and thujones in the aerial parts of A. absinthium using high-performance thin-layer chromatography. Ascending development on aluminum-backed TLC plates pre-coated with silica gel 60 F254 with toluene–acetone–glacial acetic acid (85:13:2, v/v) resulted in good resolution of bands. Their content was determined by densitometric scanning of the plates at 245 nm. The method was validated as per the International Council for Harmonisation guidelines. The method demonstrated satisfactory linearity in the range of 400–2000 ng/band for santonin (r2 0.9971) and 200–1000 ng/band for α- and β-thujones (r2 0.9977 and 0.9995). LOD was calculated to be 129.1, 57.4, and 59.9 ng/band and LOQ was estimated to be 391.4, 173.9, and 181.5 ng/band for santonin, α- and β-thujone, respectively. The method demonstrated good recovery, reproducibility, and precision for the analytes. The content of santonin in A. absinthium was found to be 3.06 ± 0.42 mg/g while total thujones was found to be 0.57 ± 0.11 mg/g on a dry weight basis. The method was precise and robust for the simultaneous estimation of santonin, α- and β-thujone. The method can be applied for the quality control of A. absinthium preparations ensuring their safe use.
An effective and straightforward analytical technique has been developed and validated for the quantification of hexaconazole fungicide used to manage fungal diseases on tomato crops. The measurement uncertainty was determined, and the environmental impact of the validated method was also assessed. The extraction of fungicide residues from tomato samples was performed using a modified QuEChERS method, followed by analysis via HPLC-UV. The validation parameters of the method, including specificity, linearity, matrix effects, limit of detection, limit of quantification, recovery, accuracy, precision, robustness, estimation of measurement uncertainty, and environmental impact, were assessed. The method’s specificity, determined by the purity of chromatographic peaks, was evident in the chromatograms of hexaconazole. The calibration curve exhibited linearity with an R2 value > 0.99. The matrix effect for the fungicide in tomato crops was found to be less than ± 20
Amorphophallus konjac, as a plant with both medicinal and edible uses that is widely valued by people, the main research on it is still glucomannan. However, a large amount of byproduct—Amorphophallus konjac flying powder (AKFP)—is discarded during the refining process. The reason for this lies in the insufficient research on the bioactive compounds and quality contained in AKFP. In this study, two qualitative methods, ultra-performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS) and gas chromatography–mass spectrometry (GC–MS), were adopted to characterize the nonvolatile and volatile components in the supercritical CO2 extract of AKFP (AKFPSE), and the contents of the four target components contained therein were determined by ultra-performance liquid chromatography–quadrupole/electrostatic field orbital trap high-resolution mass spectrometry (UPLC-Q-Exactive/MS). As a result, a total of 49 nonvolatile components and 35 volatile components were identified from the AKFPSE. In addition, the contents of N-hexanoyl-D-sphingosine (C6-SG) and N-acetyl dihydrosphingosine (C2-DSG) in the extract were determined to be 0.071 mg/g and 0.010 mg/g, respectively, and the contents of lysophosphatidylcholine 18:0 (LPC 18:0) and phosphatidylcholine 34:2 (PC 34:2) were 0.056 mg/g and 13.749 mg/g, respectively. In conclusion, this study employed highly sensitive mass spectrometry technology to comprehensively investigate the chemical composition and the content of nutritional components of AKFP from both qualitative and quantitative perspectives. This research can provide a research basis for the resource utilization and in-depth development of AKFP, and also offer a reference for the detection of lipids from other plant sources.
Biomass adsorption onto surfaces has a considerable role in many fields including biological science, drug innovation, ecological engineering, separation sciences, and the medical industry. The current research is sought to explore the interactions of microbial cells (undesirable) and proteins (desirable) with chromatographic beads by employing theoretical and experimental frameworks. The extended DLVO approach was used to analyze the interaction energies, while the cell partition index (CPI) technique was used for experimental validations. The aim of this study was to better understand the adhesion of cells and propose a simplified and cost-effective strategy for protein purification in adsorption chromatography. The results of this proposed framework revealed that salt concentration influences the interaction of cells or proteins with chromatographic beads. In hydrophobic interaction chromatography, CPI values decreased with increasing salt concentration, leading to enhanced secondary energy minimum between cells or proteins and Toyopearl Phenyl 650C beads. This effect was attributed to the exposure of hydrophobic patches, which promoted attractive forces between the interacting bodies. In contrast, during ion exchange chromatography, the CPI value increased with increased salt (NaCl) concentration, resulting in reduced interactions between cells/proteins with Toyopearl SP beads. This decrease was due to electrostatic screening and charge repulsion. These trends were consistent with calculated secondary interaction energy values obtained from xDLVO calculations. This research can assist in developing cost-effective and less complicated integrative technology, xDLVO-CPI approach, for understanding the interaction behavior. These findings may contribute to the development of less complex and more economical system for the purification of commercially important biomolecules from unclarified feedstock.
