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Transmission Low-Frequency Raman Spectroscopy for Quantification of Crystalline Polymorphs in Pharmaceutical Tablets
摘要： The purpose of this study was to quantify polymorphs of active pharmaceutical ingredients in pharmaceutical tablets using a novel transmission low-frequency Raman spectroscopy method. We developed a novel transmission geometry for low-frequency Raman spectroscopy and compared quantitative ability in transmission mode versus backscattering mode using chemometrics. We prepared two series of tablets: 1) containing different weight-based contents of carbamazepine form III and 2) including different ratios of carbamazepine polymorphs (forms I/ III). From the relationship between the contents of carbamazepine form III and partial least squares (PLS) predictions in the tablets, correlation coefficients in transmission mode (R2= 0.98) were found to be higher than in backscattering mode (R2= 0.97). The root mean square error of cross-validation (RMSECV) of the transmission mode was 3.9 compared to 4.9 for the backscattering mode. The tablets containing a mixture of carbamazepine (I/ III) polymorphs were measured by transmission low-frequency Raman spectroscopy, and it was found that the spectral shape changed according to the ratio of polymorphs: the relationship between the actual content and the prediction showed high correlation. These findings indicate that transmission low-frequency Raman spectroscopy possess the potential to complement existing analytical methods for the quantification of polymorphs.
关键词： Transmission,Carbamazepine,Pharmaceutical Tablets,Quantification,Low-Frequency Raman Spectroscopy,THz-Raman,Crystalline Polymorph
更新于2025-09-23 15:23:52
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High efficient catalytic degradation of tetracycline and ibuprofen using visible light driven novel Cu/Bi2Ti2O7/rGO nanocomposite: Kinetics, intermediates and mechanism
摘要： The photoexcited charge carriers trapping was an effective way to generate a large number of active species like O2?? and ?OH radicals to oxidize pharmaceutical molecules. In ternary Cu/Bi2Ti2O7/rGO composite Cu nanoparticles and rGO sheets act as charge carrier trappers and the suppression of e--h+ pair recombination was confirmed by Photoluminescence analysis. The Cu/Bi2Ti2O7/rGO composite exhibited higher photocatalytic degradation efficiency for degradation of ibuprofen and tetracycline molecules under visible light irradiation within 90 min. Therefore, this research designates a promising strategy for higher photoexcited charge carrier trapping photocatalyst design for efficient degradation of pharmaceutical molecules.
关键词： Nanocomposite,Visible light-driven,Hydrothermal,Pharmaceutical contamination.,Charge carrier trappers
更新于2025-09-23 15:23:52
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Cu2O photocatalyst modified antifouling polysulfone mixed matrix membrane for ultrafiltration of protein and visible light driven photocatalytic pharmaceutical removal
摘要： This study explains synthesis, characterization of an effective and efficient mixed matrix polysulfone (PSF) ultrafiltration membrane modified with Cu2O photocatalyst, synthesized using electrodeposition method, for pharmaceutical removal. Cu2O photocatalyst, polyethylene glycol, and N-methyl-2-pyrrolidone were used as additive, pore former, and solvent, respectively in the phase inversion method. Characterization techniques, such as XRD, FTIR, FESEM, FESEM-EDX, and AFM were used to characterize the photocatalyst and blended membranes so as to analyze their structural and functional attributes. Further, the membranes were analyzed by using permeation techniques to analyze their flux profiles. Similarly, antifouling nature and hydrophilicity of the membranes were studied by permeating aqueous BSA solutions and measuring the static water contact angle (SWCA), respectively. The pharmaceutical removal studies were carried out using ibuprofen (IBP). The additive improves the membrane attributes, such as flux improved from 34.24 L m-2 h-1 to 179.54 L m-2 h-1 deciphering improved porosity and pore size distribution; SWCA decreased from 71.5° to 45.3° showing increase in the hydrophilicity of the membranes; BSA adsorption decreased from 56 μg cm-2 to 27 μg cm-2; and successful removal of IBP at 86% was achieved under visible light conditions with a removal rate of 32.63 × 10-3 min-1.
关键词： antifouling,Ultrafiltration,mixed matrix membranes,pharmaceutical,Photocatalyst
更新于2025-09-23 15:21:21
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Blue LED light-driven photoelectrocatalytic removal of naproxen from water: Kinetics and primary by-products
摘要： Here, we demonstrate the viability of a ZnO/TiO2/Ag2Se thin-film composite synthesized on FTO to degrade the drug naproxen in aqueous solutions by visible-light photoelectrocatalysis (PEC). The experiments were made with 100 mL of solutions containing 5 mg L-1 drug and 50 mM Na2SO4 at natural pH, using a cell equipped with a Pt wire as cathode and the composite as photoanode exposed to a 36 W blue LED lamp. Total degradation was achieved after 210 min of electrolysis at anodic potential of +1.0 V/Ag|AgCl. This resulted from the oxidative action of hydroxyl radicals formed via direct anodic water discharge and through mediated water oxidation by photogenerated holes. The degradation rate decreased at higher naproxen concentration, but the treatment efficiency became higher due the deceleration of the parasitic reactions involving hydroxyl radicals. In chloride medium, the photoanode showed a large ability to produce active chlorine, which contributed to the oxidation of the target molecule. LC-QToF-MS analysis of treated solutions revealed the generation of four primary naphthalenic by-products, from which the initial degradation route of naproxen is proposed.
关键词： Photoelectrocatalysis,Water treatment,Oxidation by-products,Blue LED light,Pharmaceutical residue
更新于2025-09-23 15:21:01
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Optical sensors based on silver nanoparticles for determination of pharmaceuticals: An overview of advances in the last decade
摘要： This review focuses on optical nanosensors based on silver nanoparticles (Ag NPs) and demonstrates their applications in the determination of pharmaceutical compounds in the last decade. Such optical sensors have received high attention in the analytical field owing to their low cost and simplicity since they do not require any complex or expensive instrumentation. This article reviews Ag NP-based optical methods for the determination of pharmaceutical compounds from 2010 to 2020. The reported optical methods are classified into four types: spectrophotometry, spectrofluorimetry, scattering and chemiluminescence. Ag NPs play different roles in the different sensing platforms used by these methods, the details of which are carefully explained in this review. Moreover, the relevant analytical parameters of the developed methods are categorized by role and tabulated. It is hoped that this review will stimulate further research in this field with similar nanostructures.
关键词： Silver nanoparticles,Optical sensors,Pharmaceutical compounds
更新于2025-09-23 15:21:01
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Determination of citalopram in fish brain tissue: benefits of coupling laser diode thermal desorption with low- and high-resolution mass spectrometry
摘要： Recent state-of-the-art methods developed for the analysis of polar xenobiotics from different types of biological matrices usually employ liquid chromatography with mass spectrometry. However, there are limitations when a small amount of sample mass is available. For example, individual benthic invertebrates or fish tissue samples often weigh less than 100 mg (e.g., brain, liver) but are necessary to understand environmental fate and bioaccumulation dynamics. We developed ultra-fast methods based on a direct sample introduction technique. This included coupling laser diode thermal desorption with atmospheric pressure chemical ionization mass spectrometry (LDTD-APCI-MS). We then quantitated a common selective serotonin reuptake inhibitor (citalopram) in brain tissues of individual juvenile fish after in vivo exposure to environmentally relevant concentration. Two mass spectrometric methods based on low (LDTD-APCI-triple quadrupole (QqQ)-MS/MS) and high (LDTD-APCI-high-resolution product scan (HRPS)) resolutions were developed and evaluated. Individual instrument conditions were optimized to achieve an accurate and robust analytical method with minimum sample preparation requirements. We achieved very good recovery (97–108%) across the range of 1–100 ng g?1 for LDTD-APCI-HRPS. LDTD-APCI-QqQ-MS/MS showed poorer performance due to interferences from the matrix at the lowest concentration level. LDTD-APCI ionization was successfully validated for analysis of non-filtered sample extracts. Evaluation of final methods was performed for a set of real fish brain samples, including comparison of LDTD-APCI-HRPS with a previously validated LC-heated electrospray ionization-HRPS method. This new LDTD-APCI-HRPS method avoids the chromatographic step and provides important benefits such as analysis of limited sample masses, lower total sample volume (typically μL), and reduction in analysis time per sample run to a few seconds.
关键词： Ambient ionization,Green chemistry,Laser diode thermal desorption,Psychoactive pharmaceutical,Juvenile fish
更新于2025-09-23 15:21:01
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Spectroscopic Analyses - Developments and Applications || Application of Flow-Injection Spectrophotometry to Pharmaceutical and Biomedical Analyses
摘要： The discovery of new drugs, especially when many samples have to be analyzed in the minimum of time, demand the improvement or development of new analytical methods. Various techniques may be employed for this purpose. In this context, this chapter gathers the collection of paper and represents the review of past work on spectrophotometric technique coupled to a continuous flow system to determine low concentrations of several chemical species in different kinds of pharmaceutical and biological samples. A short historical background of the flow-injection analysis technique and a brief discussion of the basic principles and potential are presented. Part of this chapter is devoted to describing the sample preparation techniques, principles, and figures of merit of analytical methods. Representative applications of flow-injection spectrophotometry to pharmaceutical and biomedical analysis are also described.
关键词： biomedical samples,flow-injection,pharmaceutical,spectrophotometry
更新于2025-09-23 15:21:01
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Black phosphorus quantum dots are useful oxidase mimics for colorimetric determination of biothiols
摘要： Black phosphorus quantum dots (BP QDs) with small size are synthesized using an easy to operate thermal method. It was found that BP QDs possess oxidase-mimicking activity. They can catalyze the oxidation of the substrate 3,3′,5,5′-tetramethylbenzidine to produce a blue-colored product even in the absence of hydrogen peroxide. Active oxygen species are proved to be involved in the reaction through the experiments of radical scavenging and electron spin resonance. Biothiols including reduced glutathione and cysteine inactivate the oxidase-mimicking activity of BP QDs, concomitant to the fading of the blue solution. This provides the base for a colorimetric method for the determination of glutathione and cysteine. The decreased absorbance at 652 nm displays linear response to the concentrations of glutathione ranging from 0.1 to 5.0 μmol L?1, and cysteine from 0.1 to 10.0 μmol L?1. The detection limits are 0.02 μmol L?1 and 0.03 μmol L?1 for glutathione and cysteine, respectively. Successive determinations of 1.0 μmol L?1 glutathione and 5.0 μmol L?1 cysteine solution give relative standard deviations of 0.8% and 1.7% (n = 11), respectively. As a preliminary application, the practicability of the method was evaluated by the determination of glutathione in pharmaceutical preparations. This work not only discovers a useful oxidase mimics but also sets up a reliable platform based on BP QDs in colorimetric detection.
关键词： Cysteine,Pharmaceutical,Nanoprobe,Reactive oxygen species,Black phosphorous quantum dots,Oxidase-mimicking activity,Glutathione,Biothiols,Colorimetric method
更新于2025-09-23 15:19:57
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Investigation of minor elemental species within tablets using in situ depth profiling via laser-induced breakdown spectroscopy hyperspectral imaging
摘要： Laser-induced breakdown spectroscopy (LIBS) hyperspectral imaging allows for the determination of two-dimensional and three-dimensional spatial distributions of elemental species throughout complex samples. In this work, LIBS hyperspectral imaging was utilized to investigate minor elemental species within tablets. Representative LIBS spectra were initially collected on four complex, heterogeneous tablets, showing high concentrations of Ti in the tablet coating, with low and variable abundance of Na, Mg, and K. Principal component analysis revealed distinct resolution of the four tablets due to differences in Na, Mg, and K. Using two-dimensional LIBS hyperspectral imaging, spatial distributions of Na, Mg, and K within defined x and y regions of the tablet coating were generated. Subsequent three-dimensional LIBS hyperspectral imaging further elucidated the full x, y, and z spatial distributions of these minor elemental species within the tablet surface, tablet coating, and tablet core. As such, in situ depth profiling of the minor elemental species within each tablet was accomplished. Quantification of the homogeneity and uniformity of each tablet was determined. To our knowledge, this is the first report of multivariate analysis, LIBS, and LIBS hyperspectral imaging being utilized for the determination of both 2D and 3D spatial distributions of minor elemental species, along with quantification of tablet homogeneity, within tablets.
关键词： Chemical imaging,Laser-induced breakdown spectroscopy,Chemometrics,Pharmaceutical analysis,Atomic spectroscopy
更新于2025-09-23 15:19:57
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Portable and benchtop Raman spectrometers coupled to cluster analysis to identify quinine sulfate polymorphs in solid dosage forms and antimalarial drug quantification in solution by AuNPs-SERS with MCR-ALS
摘要： This paper proposes for the first time: (a) a qualitative analytical method based on portable and benchtop backscattering Raman spectrometers coupled to hierarchical cluster analysis (HCA) and multivariate curve resolution – alternating least-squares (MCR-ALS) to identify two polymorphs of antimalarial quinine sulfate in commercial pharmaceutical tablets in their intact forms and (b) a quantitative analytical method based on gold nanoparticles (AuNPs) as active substrates for surface-enhanced Raman scattering (SERS) in combination with MCR-ALS to quantify quinine sulfate in commercial pharmaceutical tablets in solution. The pure concentration and spectral profiles recovered by MCR-ALS proved that both formulation present different polymorphs. These results also were confirmed by two clusters observed in HCA model, according to their similarities within and among the samples that provided useful information about homogeneity of different pharmaceutical manufacturing processes. AuNPs-SERS coupled to MCR-ALS was able to quantify quinine sulfate in the calibration range from 150.00 to 200.00 ng mL-1 even with strong overlapping spectral profile of background SERS signal, proving that is a powerful ultrahigh sensitivity analytical method. This reduced linearity was validated through a large calibration range from 25.00 to 175.00 μg mL-1 used in a reference analytical method based on high performance liquid chromatography with diode array detector (HPLC-DAD) coupled to MCR-ALS for analytical validation purposes even in the presence of coeluted compound. The analytical methods herein developed are fast, because second-order chromatographic data and first-order SERS spectroscopic data where obtained in less than 6 and 2 min, respectively. Concentrations of quinine sulfate were estimated with a low root mean square error of prediction (RMSEP) values and a low relative error of prediction (REP%) in the range 1.8-6.1%.
关键词： Quinine sulfate pharmaceutical tablets,Raman spectrometer,polymorphs,HCA and MCR-ALS,AuNPs-SERS
更新于2025-09-23 15:19:57