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Biomedical Chromatography : BMC Aug 2023Baloxavir marboxil (BXM) is a polymerase acidic endonuclease inhibitor used as an antiviral drug. A simple, reliable, and robust liquid chromatographic method was...
Stability-indicating method development and validation for quantitative estimation of assay and organic impurities of antiviral drug baloxavir marboxil in drug substance and pharmaceutical dosage form using HPLC and LC-MS methods.
Baloxavir marboxil (BXM) is a polymerase acidic endonuclease inhibitor used as an antiviral drug. A simple, reliable, and robust liquid chromatographic method was developed and validated per International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) Q2(R1) for estimating the assay and impurities of BXM in drug substance and pharmaceutical formulations. The chromatographic separation was carried out on C (100 × 4.6 mm, 5 μm) with binary solvent delivery system (A:0.1% trifluoroacetic acid in water; B:0.1% trifluoroacetic-acid in acetonitrile) along with detection wavelength of 260 nm, column temperature of 57°C, flow of 1.2 mL/min and injection volume of 10 μL. All five known impurities and unknown impurities were separated well with resolution >1.7 and were estimated accurately without any interference. Recovered values and regression value were 99.5%-101.2% and R > 0.999, respectively. The recovery and linearity studies covered from 50% to 150% for assay, and quantitation limit, 120% for five BXM impurities. Stability-indicating property of the HPLC developed method was assessed from the forced degradation studies. The mass spectral data of unknown impurity formed under oxidation stress condition were discussed. The developed method was also successfully utilized for stability sample analysis of drug substance and tablet dosage form.
Topics: Humans; Chromatography, Liquid; Chromatography, High Pressure Liquid; Antiviral Agents; Drug Stability; Tandem Mass Spectrometry; Tablets; Drug Contamination
PubMed: 37052118
DOI: 10.1002/bmc.5644 -
Journal of Environmental Management Aug 2019Investigations on membrane materials for membrane distillation (MD) and its applications have been ongoing since the 1990s. However, a lack of materials that produce... (Review)
Review
Investigations on membrane materials for membrane distillation (MD) and its applications have been ongoing since the 1990s. However, a lack of materials that produce robustly stable and up-to-the-mark membranes for MD for different industrial applications remains an ongoing problem. This paper provides an overview of materials developed for MD applications. Although key aspects of published articles reviewed in this paper pertain to MD membranes synthesized for desalination, future MD can also be applied to organic wastewater containing surfactants with inorganic compounds, either with the help of hybrid treatment processes or with customized membrane materials. Many industrial discharges produce effluents at a very high temperature, which is an available driving force for MD. However, there remains a lack of cost-effective membrane materials. Amphiphobic and omniphobic membranes have recently been developed for treating emulsified and shale gas produced water, but the problem of organic fouling and pore wetting remains a major challenge, especially when NaCl and other inorganic impurities are present, which further deteriorate separation performance. Therefore, further advancements in materials are required for the treatment of emulsified industrial wastewater containing surfactants, salts, and for oil or shale gas wastewater for its commercialized reuse. Integrated MD systems, however, may represent a major change in shale gas wastewater and emulsified wastewater that are difficult to treat.
Topics: Distillation; Membranes, Artificial; Natural Gas; Wastewater; Water Purification
PubMed: 31078929
DOI: 10.1016/j.jenvman.2019.04.105 -
Journal of the American Chemical Society Jun 2023Metal-organic frameworks (MOFs) are crystalline, porous solids constructed from organic linkers and inorganic nodes that are promising for applications in chemical...
Metal-organic frameworks (MOFs) are crystalline, porous solids constructed from organic linkers and inorganic nodes that are promising for applications in chemical separations, gas storage, and catalysis, among many others. However, a major roadblock to the widespread implementation of MOFs, including highly tunable and hydrolytically stable Zr- and Hf-based frameworks, is their benchtop-scalable synthesis, as MOFs are typically prepared under highly dilute (≤0.01 M) solvothermal conditions. This necessitates the use of liters of organic solvent to prepare only a few grams of MOF. Herein, we demonstrate that Zr- and Hf-based frameworks (eight examples) can self-assemble at much higher reaction concentrations than are typically utilized, up to 1.00 M in many cases. Combining stoichiometric amounts of Zr or Hf precursors with organic linkers at high concentrations yields highly crystalline and porous MOFs, as confirmed by powder X-ray diffraction (PXRD) and 77 K N surface area measurements. Furthermore, the use of well-defined pivalate-capped cluster precursors avoids the formation of ordered defects and impurities that arise from standard metal chloride salts. These clusters also introduce pivalate defects that increase the exterior hydrophobicity of several MOFs, as confirmed by water contact angle measurements. Overall, our findings challenge the standard assumption that MOFs must be prepared under highly dilute solvothermal conditions for optimal results, paving the way for their scalable and user-friendly synthesis in the laboratory.
PubMed: 37294975
DOI: 10.1021/jacs.3c02787 -
Journal of Pharmaceutical and... Jan 2021A pure β-D-Glucopyranosiduronic acid metabolite (≥98.0 % purity and a single impurity ≤0.50 %) was requested for biological studies. Due to its unusual...
A pure β-D-Glucopyranosiduronic acid metabolite (≥98.0 % purity and a single impurity ≤0.50 %) was requested for biological studies. Due to its unusual instability, the purification of the glucuronide metabolite was extremely challenging. Initially, the crude sample (89 % HPLC area purity) was purified on a Waters SunFire C OBD column with 40 mM ammonium acetate buffer and acetonitrile as the mobile phase under a gradient program. The purified glucuronide metabolite solid was obtained by evaporation and lyophilization. However, this procedure yielded the target compound with 97.6 % HPLC area purity and did not meet the requirements. Through the investigation, lyophilization was identified as the key step for the purity of the metabolite, and further lyophilization resulted in an increased amount of the degraded impurities. To better understand the compound, stability studies of the purified metabolite were conducted under sample media, organic solvent, acid, base, and light exposure. The compound was observed to be extremely unstable in water, acid, base and methanol, and sensitive to light, but relatively stable in ammonium acetate buffer (pH 5.0). Taking into account compound stability and the initial purification method, the improved purification procedure was successfully developed and the purified glucuronide metabolite was obtained with 99.2 % HPLC area purity and 0.39 % of the largest single impurity.
Topics: Chromatography, High Pressure Liquid; Glucuronides; Methanol; Solvents
PubMed: 33010500
DOI: 10.1016/j.jpba.2020.113651 -
Food Additives & Contaminants. Part A,... Feb 2019Pigment Red 57 (Colour Index No. 15850, PR57) and Pigment Red 57:1 (Colour Index No. 15850:1, PR57:1) are certifiable in the USA as the color additives D&C Red No. 6...
Identification and quantification of the decarboxylated analogue of Pigments Red 57 and 57:1 in the color additives D&C Red No. 6, D&C Red No. 7, and their lakes, using a chelating agent and UHPLC.
Pigment Red 57 (Colour Index No. 15850, PR57) and Pigment Red 57:1 (Colour Index No. 15850:1, PR57:1) are certifiable in the USA as the color additives D&C Red No. 6 (R6) and D&C Red No. 7 (R7) for use in drugs and cosmetics. In the EU, PR57:1 is permitted in cosmetics and also as a food additive (E180) for colouring edible cheese rinds. The USFDA batch-certifies R6, R7, and their lakes in accordance with limiting specifications for impurities stated in the Code of Federal Regulations (CFR). In the current work, an impurity not specified in the CFR was studied because of its consistent presence in samples of R6 and R7 submitted for certification. Using spectroscopic methods, the impurity was tentatively identified as 4-[(4-methyl-2-sulfophenyl)azo]-3-naphthalenol (DPR57), the decarboxylated analogue of PR57 and PR57:1. Its identity was confirmed by synthesising DPR57 and determining that the UHPLC retention time, UV/visible spectrum and mass spectrum of the synthetic material were identical to those of the impurity. Using the synthesised DPR57 as a reference material, the impurity was quantified in 43 batches of R6, R7, and lakes produced by eight different manufacturers. Calibration curves ranging from 0.02% to 1.00% (w/w) were prepared by plotting the UHPLC area of DPR57 at 485 nm against its concentration. DPR57 levels ranged from < 0.02% to 0.50%. To facilitate dissolution of the color additive samples for DPR57 analysis, a relatively simple procedure was developed by adapting a previously published method that involves use of a basic solution of the chelating agent EDTA and the organic solvent N,N'-dimethylformamide. A source for DPR57 contamination of the color additives is also proposed.
Topics: Chelating Agents; Chromatography, High Pressure Liquid; Color; Decarboxylation; Food Additives; Food Coloring Agents
PubMed: 30696369
DOI: 10.1080/19440049.2018.1556404 -
Waste Management (New York, N.Y.) Feb 2018The application of organic soil amendments is a common measure to prevent structural degradation of agricultural soils and to maintain and improve long-term soil...
The application of organic soil amendments is a common measure to prevent structural degradation of agricultural soils and to maintain and improve long-term soil fertility. Solid residues from anaerobic digestion of municipal organic waste (MOW) are rich in nutrients and organic matter and have a promising potential to be used as soil amendment. However, no study has related amendment properties of MOW digestate of one origin to different treatment procedures. We therefore investigated the impact of drying, composting and sieving on final digestate properties and specifically nutrient availability and heavy metal and carbon elution. Samples were provided by a semi-industrial two-stage biogas plant with dry fermentation of MOW. Results confirm that in comparison to drying, composting of MOW digestates leads to a significant increase of K, P, Mg, Ca, Cd and Cr in the digestates. Sieving of composted digestates showed that heavy metals are not evenly distributed and that heavy metal concentration in the digestate increases with decreasing mesh sizes (highest concentrations in the fractions <1 mm). Although the element concentration is higher in composted batches, the water-extractability of nutrients, heavy metals and carbon is significantly lower from composted over dried digestates. A significant correlation was found between the dissolution of Zn, Ni, Ca and Mg and pH of eluate as well as dissolved organic carbon (DOC) release (R > 0.7, p<0.05). Results confirm that the extent of carbon elution depends on the degradation rate of digestates. DOC may therefore be a good measure to evaluate digestate stability and to decide on treatment measures.
Topics: Agriculture; Cities; Composting; Metals, Heavy; Sewage; Soil; Waste Management
PubMed: 29191369
DOI: 10.1016/j.wasman.2017.11.022 -
Water Research Sep 2016For successful application of a zero-valent iron (ZVI) system, of particular interest is the performance of ZVI under various conditions. The current review... (Review)
Review
For successful application of a zero-valent iron (ZVI) system, of particular interest is the performance of ZVI under various conditions. The current review comprehensively summarizes the potential effects of the major influencing factors, such as iron intrinsic characteristics (e.g., surface area, iron impurities and oxide films), operating conditions (e.g., pH, dissolved oxygen, iron dosage, iron pretreatment, mixing conditions and temperature) and solution chemistry (e.g., anions, cations and natural organic matter) on the performance of ZVI reported in literature. It was demonstrated that all of the factors could exert significant effects on the ZVI performance toward contaminants removal, negatively or positively. Depending on the removal mechanisms of the respective contaminants and other environmental conditions, an individual variable may exhibit different effects. On the other hand, many of these influences have not been well understood or cannot be individually isolated in experimental or natural systems. Thus, more research is required in order to elucidate the exact roles and mechanisms of each factor in affecting the performance of ZVI. Furthermore, based on these understandings, future research may attempt to establish some feasible strategies to minimize the deteriorating effects and utilize the positive effects so as to improve the performance of ZVI.
Topics: Iron; Oxygen; Solutions; Water Pollutants, Chemical
PubMed: 27206056
DOI: 10.1016/j.watres.2016.05.031 -
Journal of Pharmaceutical and... Sep 2023Ofloxacin ear drops contain a large proportion of organic solvents, which have a great effect on the photodegradation of ofloxacin. The photodegradation impurities of...
Study on the impurity profile and influencing factors of photodegradation in non-aqueous ofloxacin ear drops using liquid chromatography combined with ion trap/time-of-flight mass spectrometry.
Ofloxacin ear drops contain a large proportion of organic solvents, which have a great effect on the photodegradation of ofloxacin. The photodegradation impurities of ofloxacin in aqueous solution has been studied, however, the photodegradation of ofloxacin in non-aqueous solution with a high proportion of organic solvents has not been reported. In this article, the impurity profile in non-aqueous ofloxacin ear drops was studied for further improvement of official monograph in pharmacopoeia and quality control of drug. The liquid chromatography combined with ion trap/time-of-flight mass spectrometry was applied to separate and characterize the structures of the impurities in non-aqueous ofloxacin ear drops. Mass fragmentation pattern of ofloxacin and its impurities were studied. The structures of seventeen impurities in ofloxacin ear drops were elucidated based on the high-resolution MS data in positive ion modes, and ten of them were unknown impurities. The results showed that the impurity profile of non-aqueous ofloxacin solution was significantly different from that of aqueous ofloxacin solution. The effects of packaging materials and excipients on the photodegradation of ofloxacin ear drops were also investigated. The results of correlation analysis showed that the packaging materials with low light transmittance could reduce the light degradation, and ethanol of excipients could significantly decrease the light stability of ofloxacin ear drops. This study revealed the impurity profile and key factors affecting the photodegradation of non-aqueous ofloxacin ear drops, and guided enterprises to improve drug prescription and packaging materials to ensure the safety of drug use by the public.
Topics: Photolysis; Excipients; Drug Contamination; Chromatography, Liquid; Gas Chromatography-Mass Spectrometry; Chromatography, High Pressure Liquid
PubMed: 37245330
DOI: 10.1016/j.jpba.2023.115476 -
Luminescence : the Journal of... Jan 2023The lighting industry currently accounts for a significant proportion of all energy demand. Luminescent white lighting is often impure, inefficient, expensive, and...
The lighting industry currently accounts for a significant proportion of all energy demand. Luminescent white lighting is often impure, inefficient, expensive, and detrimentally emits as a point source, meaning the light is emitted from a focused point. A luminescent light diffuser offers the potential to create a spatially broad lighting fixture. We developed a luminescent light diffuser consisting of three commercially available luminescent dye species (rhodamine 6G, fluorescein, 7-diethylamino-4-methylcoumarin) dispersed within a polymer matrix (polyvinyl alcohol), or commercial paint, and coated on a planar waveguide. A Light-emitting diode (LED) (385 nm) is directed into the waveguide which excites the luminescent species, coating the panel, creating a device that emits spatially broad pure white light. As the emission depends on escape cone emission from the waveguide, the device's emission was found to depend highly on the coating film quality and components. We present two systems: a small 40 mm × 40 mm prototype, made using standard water-soluble polymer (polyvinyl alcohol), to study the underlying operational principles, and a 100 mm 100 mm device with optimized efficiency fabricated with a clear commercial paint. By doping the polymer matrix with scattering silica microparticles we achieved a maximum photon outcoupling efficiency of 78%, whilst maintaining colour purity with an increased device size of more than 300 times (compared with the input LED). This work shows that it is possible to construct an inexpensive and spatially broad lighting source, whilst maintaining colour purity at a low cost.
Topics: Lighting; Polyvinyl Alcohol; Luminescence; Light; Polymers
PubMed: 36433880
DOI: 10.1002/bio.4416 -
Membranes Apr 2022Inorganic-organic composite membranes (IOCMs) are an alternative separation method developed for their straightforward process, economic benefits, and ease of scaling...
Inorganic-organic composite membranes (IOCMs) are an alternative separation method developed for their straightforward process, economic benefits, and ease of scaling up. The IOCMs in this study were prepared from a biopolymer chitosan matrix and rice husk-based silica filler to remove impurities from crude biodiesel. The IOCMs were prepared through phase inversions, in which the priorly prepared silica particles were dispersed in the dope solution of chitosan. The maximum loading of the silica particles was 60%, capable of reducing the soap level, free glycerol level, and acid number from 547.9 to 12.2 mg/L, 54 to 0.041%, and 2.02 to 1.12 mgKOH/g. These reduced impurity values have satisfied the standardized quality. The chemical composition and morphology of the IOCM was characterized using Fourier-transform infrared spectroscopy and scanning electron microscope-energy dispersive X-Ray spectroscopy. The IOCM water absorption-based porosity and swelling degree were studied as well. Further investigation using isothermal modeling revealed the adsorption dependency against the Sips model equation (R = 0.99 and root-mean-square errors = 1.77 × 10). Even though regeneration is still a challenging factor in this study, the IOCM prepared from chitosan and rice husk-derived silica particles could be used in crude biodiesel purification.
PubMed: 35448404
DOI: 10.3390/membranes12040435