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Separation Science Plus Jan 2020Many over-the-counter drug products lack official compendial analytical methods. As a result, the United States Pharmacopeia and the United States Food and Drug...
Many over-the-counter drug products lack official compendial analytical methods. As a result, the United States Pharmacopeia and the United States Food and Drug Administration are seeking to develop and validate new methods to establish analysis standards for the assessment of the pharmaceutical quality of over-the-counter drug products. Diphenhydramine and phenylephrine hydrochloride oral solution, a combination drug product, was identified as needing a compendial standard. Therefore, an ultra-high-performance liquid chromatography method was developed to separate and quantify the two drug compounds and eleven related organic impurities. As part of a robustness study, the separation was demonstrated using different high-performance liquid chromatography systems and columns from different manufacturers, and showed little dependence with changes in flow rate, column temperature, detection wavelength, injection volume and mobile phase gradient. The method was then validated conformant with the International Council for Harmonisation guidelines. For impurities, adequate specificity, linearity, accuracy and precision were demonstrated. For assay, a slight modification to the injection volume was necessary to achieve adequate analytical performance. With successful development and validation, these methods were shown to be suitable for their intended purpose and may be considered for adoption as compendial procedures.
PubMed: 32076656
DOI: 10.1002/sscp.201900084 -
Forensic Science International Apr 2020This work examines organic impurity profiles of 3,4-methylenedioxymethamphetamine (MDMA) that has been synthesised from the "pre-precursors" catechol...
This work examines organic impurity profiles of 3,4-methylenedioxymethamphetamine (MDMA) that has been synthesised from the "pre-precursors" catechol (1,2-dihydroxybenzene) and eugenol, via a safrole intermediate. MDMA was synthesised from the catechol- and eugenol-derived safrole intermediate via two routes, which resulted in the synthesis of MDMA from catechol via two routes (Route 1A and 1B) and from eugenol via two routes (Route 2A and 2B). Twelve organic impurities were identified in MDMA synthesised via Routes 1A and 1B, and eleven organic impurities were identified in MDMA synthesised via Routes 2A and 2B. Route specific organic impurities were identified in MDMA that indicated the "pre-precursors" catechol and eugenol were used in the respective synthetic routes. Route specific organic impurities were also identified in MDMA that indicated the route used to synthesise safrole from the "pre-precursor" and the route used to synthesise MDMA from safrole. Thus, the use of the "pre-precursors" catechol and eugenol and the synthetic route utilised could be ascertained by the organic impurity profiling of MDMA under the conditions used here.
PubMed: 32070849
DOI: 10.1016/j.forsciint.2020.110176 -
Biomedical Chromatography : BMC Feb 2023Apalutamide, an androgen receptor inhibitor, is used to treat prostate cancer. A stability-indicating high-performance liquid chromatography method was developed for the...
Apalutamide, an androgen receptor inhibitor, is used to treat prostate cancer. A stability-indicating high-performance liquid chromatography method was developed for the estimation of assay and organic impurities of apalutamide in drug substance and in tablet dosages using Design of Experiments. The chromatographic separation was achieved within 30 min using Atlantis dC , 100 × 4.6 mm, 3.0 μm and the binary gradient program (10 mm KH PO , pH 3.5; acetonitrile). The detection wavelength, flow rate, column temperature and injection volume used were 270 nm, 1.0 ml/min, 45°C and 10 μl, respectively. The interaction of independent variables (pH, column temperature and flow rate) and their influences on HPLC parameters were studied using a central composite design, and then the peak separation and elution behaviors between apalutamide and its seven impurities were determined. The method validation was performed for linearity, detection limit, quantitation limit, accuracy, precision and robustness as per the International Conference on Harmonization. A high-quality recovery with good precision (91.7-106.0%) and correlations (r > 0.997) within a linear range of 0.12-2.24 μg/ml (0.05-0.3%, w/w) were achieved consistently for assay and organic impurities of apalutamide. The stability-indicating characteristics of the proposed method were assessed through forced degradation and mass balance studies. An effort was made to figure out the chemical structures of newly formed degradation products (DP1-DP5) using LC-MS/MS.
Topics: Male; Humans; Chromatography, Liquid; Chromatography, High Pressure Liquid; Tandem Mass Spectrometry; Antineoplastic Agents; Drug Contamination; Drug Stability; Reproducibility of Results
PubMed: 36409057
DOI: 10.1002/bmc.5549 -
Materials (Basel, Switzerland) Jun 2023Charge transport characteristics in organic semiconductor devices become altered in the presence of traps due to defects or impurities in the semiconductors. These traps...
Charge transport characteristics in organic semiconductor devices become altered in the presence of traps due to defects or impurities in the semiconductors. These traps can lead to a decrease in charge carrier mobility and an increase in recombination rates, thereby ultimately affecting the overall performance of the device. It is therefore important to understand and mitigate the impact of traps on organic semiconductor devices. In this contribution, the influence of the capture and release times of trap states, recombination rates, and the Lorentz force on the net charge of a low-mobility organic semiconductor was determined using the finite element method (FEM) and Hall effect method through numerical simulations. The findings suggest that increasing magnetic fields had a lesser impact on net charge at constant capture and release times of trap states. On the other hand, by increasing the capture time of trap states at a constant magnetic field and fixed release time, the net charge extracted from the semiconductor device increased with increasing capture time. Moreover, the net charge extracted from the semiconductor device was nearly four and eight times greater in the case of the non-Langevin recombination rates of 0.01 and 0.001, respectively, when compared to the Langevin rate. These results imply that the non-Langevin recombination rate can significantly enhance the performance of semiconductor devices, particularly in applications that require efficient charge extraction. These findings pave the way for the development of more efficient and cost-effective electronic devices with improved charge transport properties and higher power conversion efficiencies, thus further opening up new avenues for research and innovation in this area of modern semiconductor technology.
PubMed: 37445005
DOI: 10.3390/ma16134691 -
Proceedings of the National Academy of... Apr 2022Knowledge of deformation mechanisms in aragonite, one of the three crystalline polymorphs of CaCO3, is essential to understand the overall excellent mechanical...
Knowledge of deformation mechanisms in aragonite, one of the three crystalline polymorphs of CaCO3, is essential to understand the overall excellent mechanical performance of nacres. Dislocation slip and deformation twinning were claimed previously as plasticity carriers in aragonite, but crystallographic features of dislocations and twins have been poorly understood. Here, utilizing various transmission electron microscopy techniques, we reveal the atomic structures of twins, partial dislocations, and associated stacking faults. Combining a topological model and density functional theory calculations, we identify complete twin elements, characters of twinning disconnection, and the corresponding twin shear angle (∼8.8°) and rationalize unique partial dislocations as well. Additionally, we reveal an unreported potential energy dissipation mode within aragonite, namely, the formation of nanograins via the pile-up of partial dislocations. Based on the microstructural comparisons of biogenic and abiotic aragonite, we find that the crystallographic features of twins are the same. However, the twin density is much lower in abiotic aragonite due to the vastly different crystallization conditions, which in turn are likely due to the absence of organics, high temperature and pressure differences, the variation in inorganic impurities, or a combination thereof. Our findings enrich the knowledge of intrinsic crystal defects that accommodate plastic deformation in aragonite and provide insights into designing bioengineering materials with better strength and toughness.
PubMed: 35357967
DOI: 10.1073/pnas.2122218119 -
ACS Omega Nov 2022In this study, the aim was to prepare drug-releasing clay mineral particles using raw (CaMt) and purified (PMt) montmorillonite and to compare and determine the effects...
In this study, the aim was to prepare drug-releasing clay mineral particles using raw (CaMt) and purified (PMt) montmorillonite and to compare and determine the effects of purification on the properties of montmorillonite. Montmorillonite clay minerals are used in several pharmaceutical and cosmetic products due to their many favorable properties, such as cation exchange capacity, adsorption capability, high specific surface area, and biocompatibility. Recently, several types of clay minerals have been widely studied for drug delivery applications due to their unique properties. The purification of montmorillonite is considered as a potentially useful step which may decrease the toxicity of impurities but which may increase the adsorption capacity of the montmorillonite. However, the effects on the toxicity and drug-release properties of purified montmorillonite have never been compared to that of raw montmorillonite. Montmorillonite was purified through decomposition of carbonates, dissolution of hydroxides, oxidation of organic materials, dialysis, and sedimentation. The raw and the purified montmorillonite were characterized using XRD, FTIR, and cation exchange capacities. Then, the cytotoxicity of raw and purified montmorillonite on normal hFOB cells was investigated to assess their biocompatibility . Finally, the efficacy of montmorillonite as a drug-delivering agent was investigated using cytotoxicity assays with the MCF7 cell line. The antitumor drug doxorubicin was loaded onto particles through electrostatic forces at 97.99% for CaMt and 96.79% for PMt. The drug-loading efficiency and release behavior of both clay minerals were determined. Results showed that both raw and purified montmorillonite did not significantly reduce the viability of normal cells at low concentrations (<500 μg/mL). At high concentrations, both raw and purified montmorillonite showed significant toxicity and the effect of impurities on toxicity were also more pronounced. Although drug loading was successful for both clay minerals there were differences in their controlled drug-release behavior. Doxorubicin-loaded raw and purified clay minerals significantly reduced MCF7 cell viability similar to pure DOX.
PubMed: 36340105
DOI: 10.1021/acsomega.2c04510 -
Life (Basel, Switzerland) Sep 2022Most experimental results that guide research related to the origin of life are from laboratory simulations of the early Earth conditions. In the laboratory, emphasis is... (Review)
Review
Most experimental results that guide research related to the origin of life are from laboratory simulations of the early Earth conditions. In the laboratory, emphasis is placed on the purity of reagents and carefully controlled conditions, so there is a natural tendency to reject impurities and lack of control. However, life did not originate in laboratory conditions; therefore, we should take into consideration multiple factors that are likely to have contributed to the environmental complexity of the early Earth. This essay describes eight physical and biophysical factors that spontaneously resolve aqueous dispersions of ionic and organic solutes mixed with mineral particles and thereby promote specific chemical reactions required for life to begin.
PubMed: 36143465
DOI: 10.3390/life12091429 -
Analytical Sciences : the International... Jan 2023Differential scanning calorimetry can be used to measure the impurity contents of pure organic substances on the principle of freezing-point depression. Impurity...
Differential scanning calorimetry can be used to measure the impurity contents of pure organic substances on the principle of freezing-point depression. Impurity determination by differential scanning calorimetry with a dynamic method, which has the advantages of speediness and convenience, remains to be explored. Here, a series of acetanilide and dibenzothiophene samples with various purities was prepared through zone melting, and the samples were then analyzed by gas chromatography-mass spectrometry. A modified dynamic method, including encapsulating the analyte in a volatile pan through cold welding, remelting the analyte with a low heating rate, calculating the melted fraction considering the area of the tailing under the heat-flow curve, and reducing the error from solid-solution formation, is proposed. Encapsulating with a volatile pan using a proper torque gave an accurate result. Remelting gave a lower impurity content and a more narrow and sooth peak of heat-flow compared with the first melting. The impurity-content results calculated by the modified method were usually higher than those calculated by the ASTM standard method. For acetanilide and dibenzothiophene with impurity contents of less than 0.30%, the modified dynamic method showed good accuracy. The proposed method is applicable to determination of reference materials of organic substances with high purity owing to its accuracy and convenience.
Topics: Calorimetry, Differential Scanning; Gas Chromatography-Mass Spectrometry; Hot Temperature; Acetanilides
PubMed: 36266561
DOI: 10.1007/s44211-022-00205-4 -
RSC Advances Feb 2023For the last several decades, semiconducting materials and nanocomposites have received a lot of interest in generating highly efficient photocatalysts to destroy...
For the last several decades, semiconducting materials and nanocomposites have received a lot of interest in generating highly efficient photocatalysts to destroy organic pollutants and eradicate bacteria. This study uses a simple deposition and precipitation approach at ambient temperature to create a unique and efficient AgI-CdO heterojunction. DRS, IR, SEM, EDS, XRD, EIS, and TEM were utilized to identify the material. SEM and TEM investigation depict the completely spherical, hexagonal forms and zigzag cubes for synthesized AgI-CdO. The EDX spectra reveal the presence of Ag, I, Cd, and O elements without impurity peaks showing that the prepared samples are highly pure. The activity of the synthesized materials was tested by degrading two different chromophoric dyes and a drug derivative (paracetamol) in an aqueous suspension under visible light. In addition, the activity of the most active catalyst was compared with Degussa P25, Fenton's reagent, and under sunlight for degradation of MB and RhB under similar conditions. Photolysis of paracetamol was also looked at using HPLC to identify intermediates formed in the photo-oxidation process. In addition, antibacterial activity was also investigated with the synthesized CdO-AgI nanocomposite against human pathogenic bacterial strains and compared with that of pure materials like AgI and standard ampicillin. The results showed excellent activity with the composite material, which could be due to the higher surface areas and the interactions between AgI and CdO nanoparticles. Quenching investigations revealed O˙ and holes are principal reactive species. A viable photocatalytic degradation mechanism for organic pollutant elimination over the AgI-CdO nanocomposite has been sketched out based on the obtained results.
PubMed: 36777948
DOI: 10.1039/d2ra07626h -
Chemistry, An Asian Journal Oct 2023Metal-organic frameworks (MOFs) are promising porous materials that have huge potential for gas separation when put in the membrane configuration. MOFs have huge... (Review)
Review
Metal-organic frameworks (MOFs) are promising porous materials that have huge potential for gas separation when put in the membrane configuration. MOFs have huge potential due to certain salient features of the MOFs such as excellent pore size, ease of tuning the pore chemistry, higher surface area, and chemical and thermal stabilities. MOFs have been explored for various gas separation and storage applications. This review discusses various approaches for fabricating MOFs-based membranes for the separation of H gas from a variety of feeds having various gases CO , CO, N , and CH as impurities. The emphasis has been put on three types of membranes for H separation which include MOFs-based hollow fibrous/tubular/disk membranes, MOFs-based mixed matrix membranes (MMMs), and MOFs-based stand-alone membranes. In addition, various challenges such as reducing inhomogeneity between MOFs and polymeric matrices have also been discussed. Similarly, the approaches to successfully decorating MOFs on different supports in different configurations have been explained. The possible ways of improving the MOFs-based membranes for H have also been discussed.
PubMed: 37818783
DOI: 10.1002/asia.202300619