Simple spectrophotometric methods for the determination of amlodipine and atorvastatin in bulk and tablets

Background Simultaneous spectrophotometric determination of samples containing more than one analyte presents analytical challenge; the choice of an analytical procedure is strictly related to the extent of overlapping between the individual absorption peaks of these components; if the absorption peaks are satisfactorily resolved, the determination is not problematic, but if the individual component signals are partly or totally overlapped, then powerful techniques are needed. Combined amlodipine and atorvastatin are typical example where special techniques are needed to resolve bands overlapping. Results Application of multiwavelength regression and absorbance factor methods to the analysis of atorvastatin and amlodipine combination proved to be satisfactorily capable of accurate and precise determination of the two analytes. The two methods recoveries were very close to the expected analytes concentrations, and the precision of the methods was < 2% relative standard deviation. Statistical comparison indicated that there is no significant difference between the assay results obtained by the two method as the calculated t values 0.91 and 1.13 for amlodipine and atorvastatin, respectively, were less than the tabulated t value 2.23 at 95% confidence level. Conclusion The proposed methods are accurate, precise, simple and inexpensive. They can be applied successfully to the analysis of the two drugs in combined dosage form.

Demographic feedbacks can hamper the spatial spread of a gene drive

This paper is concerned with a reactionddiffusion system modeling the fixation and the invasion in a population of a gene drive (an allele biasing inheritance, increasing its own transmission to offspring). In our model, the gene drive has a negative effect on the fitness of individuals carrying it, and is therefore susceptible of decreasing the total carrying capacity of the population locally in space. This tends to generate an opposing demographic advection that the gene drive has to overcome in order to invade. While previous reaction-diffusion models neglected this aspect, here we focus on it and try to predict the sign of the traveling wave speed. It turns out to be an analytical challenge, only partial results being within reach, and we complete our theoretical analysis by numerical simulations. Our results indicate that taking into account the interplay between population dynamics and population genetics might actually be crucial, as it can effectively reverse the direction of the invasion and lead to failure. Our findings can be extended to other bistable systems, such as the spread of cytoplasmic incompatibilities caused by Wolbachia.

Comparison of Different d-SPE Sorbent Performances Based on Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) Methodology for Multiresidue Pesticide Analyses in Rapeseeds

Pesticide extraction in rapeseed samples remains a great analytical challenge due to the complexity of the matrix, which contains proteins, fatty acids, high amounts of triglycerides and cellulosic fibers. An HPLC-MS/MS method was developed for the quantification of 179 pesticides in rapeseeds. The performances of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method were evaluated using different dispersive solid-phase extraction (d-SPE) sorbents containing common octadecylsilane silica/primary–secondary amine adsorbent (PSA/C18) and new commercialized d-SPE materials dedicated to fatty matrices (Z-Sep, Z-Sep+, and EMR-Lipid). The analytical performances of these different sorbents were compared according to the SANTE/12682/2019 document. The best results were obtained using EMR-Lipid in terms of pesticide average recoveries (103 and 70 of the 179 targeted pesticides exhibited recoveries within 70–120% and 30–70%, respectively, with low RSD values). Moreover, the limits of quantification (LOQ) range from 1.72 µg/kg to 6.39 µg/kg for 173 of the pesticides. Only the recovery for tralkoxydim at 10 μg/kg level was not satisfactory (29%). The matrix effect was evaluated and proved to be limited between −50% and 50% for 169 pesticides with this EMR-Lipid and freezing. GC-Orbitrap analyses confirmed the best efficiency of the EMR-Lipid sorbent for the purification of rapeseeds.

Concurrent chromatographic determination of pseudoephedrine and loratadine from combination syrups and tablets

Background Chromatographic separation of polar and nonpolar compounds when presented in combined dosage forms has always been considered as great analytical challenge. Separation and retention of both polar and nonpolar compounds by the same stationary phase can be a useful approach for analyses of complex samples with such a difference in chemical properties. Loratadine (nonpolar) and pseudoephedrine (polar) are typical examples of this situation. Results The Box–Behnken design was used to optimize the separation process, an efficient separation of loratadine and pseudoephedrine was achieved within 6 min; employing a mixture of 16.0 mM ammonium acetate buffer (pH 4.5) and acetonitrile (23:77, v/v) as isocratic mobile phase, pumped at 1.0 mL/min through a Zorbax cyanopropyl column (250 mm × 4.6 mm, 5 μm), the analytes were detected at 250 nm. Under the same conditions, separation of sodium benzoate preservative co-formulated with the two analytes in syrup formulation was also achieved. The calibration curve demonstrated excellent linearity in the range of 24.6–123.2 μg/mL and 594.8–2974.0 μg/mL for loratadine and pseudoephedrine, respectively with determination coefficient (r2) > 0.999. Conclusion The method’s accuracy bias < 2.0%, repeatability and intermediate precision (%RSD < 2.0%) were verified. In addition, system suitability parameters were found within the acceptable limits. Satisfactory results were obtained upon the application of the validated method to the analysis of commercial tablet and syrup formulations.

Negotiating the Descriptive–Normative Frontier of Complexity Research in the Anthropocene

This mini-review article offers a commentary on a singular analytical problem faced by legal scholars who use complexity theory and methods in legal research on climate change and the “Anthropocene”. It positions such research as a subset of complexity scholarship in law, which is generally faced with the methodological and analytical challenge of negotiating and reconciling empirical description with normative prescription. It argues that this challenge is particularly acute for legal scholars writing on climate change and the Anthropocene. Using examples from scholars writing about “Earth systems law,” it demonstrates how a heavy reliance on complexity-based empirical data as a source material for normative claim-making can distract scholars from important but difficult questions about normative legitimacy and how legal change happens at multiple levels. The special epistemological challenges posed by climate change and the Anthropocene should demand that scholars writing in this domain be especially mindful and explicit on how they link complexity descriptions to the normative claims they make, both for the sake of scientific credibility as well as for the legitimacy and viability of their propositions.

Uncovering the Release of Micro/nanoplastics from Disposable Face Masks at Times of COVID-19

<p>This study aims to assess the environmental impact of discarded face masks, that are a source of emerging concern as indicated by most recent literature, although still little investigated. Herein we evaluated micro- and nanoplastic particles that can be released from face mask once subject to environmental conditions. Exposure to simulated-low shear forces demonstrated to be effective in breaking and fragmenting face mask tissue into smaller debris. Even at low shear energy densities, a single mask could release in water thousands of microplastic fibers and up to 10^11 submicrometric particles. The latter were quantified using flow cytometry that was proven to be a promising technique for nanoplastic counting, thus improving our understanding on distribution and fate of NPs still representing a great analytical challenge in plastic pollution research. </p>

Uncovering the Release of Micro/nanoplastics from Disposable Face Masks at Times of COVID-19

<p>This study aims to assess the environmental impact of discarded face masks, that are a source of emerging concern as indicated by most recent literature, although still little investigated. Herein we evaluated micro- and nanoplastic particles that can be released from face mask once subject to environmental conditions. Exposure to simulated-low shear forces demonstrated to be effective in breaking and fragmenting face mask tissue into smaller debris. Even at low shear energy densities, a single mask could release in water thousands of microplastic fibers and up to 10^11 submicrometric particles. The latter were quantified using flow cytometry that was proven to be a promising technique for nanoplastic counting, thus improving our understanding on distribution and fate of NPs still representing a great analytical challenge in plastic pollution research. </p>

Capturing site-specific heterogeneity with large-scale N-glycoproteome analysis

ABSTRACTProtein glycosylation is a highly important, yet a poorly understood protein post-translational modification. Thousands of possible glycan structures and compositions create potential for tremendous site heterogeneity and analytical challenge. A lack of suitable analytical methods for large-scale analyses of intact glycopeptides has ultimately limited our abilities to both address the degree of heterogeneity across the glycoproteome and to understand how it contributes biologically to complex systems. Here we show that N-glycoproteome site-specific microheterogeneity can be captured via large-scale glycopeptide profiling with methods enabled by activated ion electron transfer dissociation (AI-ETD), ultimately characterizing 1,545 N-glycosites (>5,600 unique N-glycopeptides) from mouse brain tissue. Moreover, we have used this large-scale glycoproteomic data to develop several new visualizations that will prove useful for analyzing intact glycopeptides in future studies. Our data reveal that N-glycosylation profiles can differ between subcellular regions and structural domains and that N-glycosite heterogeneity manifests in several different forms, including dramatic differences in glycosites on the same protein.