Forced Degradation Studies on Sodium Picosulfate and Separation of 15 Process Related Impurities/Degradants by HPLC

A selective, precise and stability-indicating, high performance liquid chromatographic method was developed for the analysis of active ingredient sodium Picosulfate and forced degradation behavior was studied. The current article describes forced degradation behavior of the Sodium Picosulfate drug substance in detail by analyzing 15 process related/degradants in a single HPLC method under ICH recommended stressed conditions. Mobile phase comprised of 0.01 M of Disodium hydrogen phosphate and 0.01 M of potassium phosphate monobasic buffer and 1 mL of triethyl amine in 1000 mL water adjusted to pH 7.5 with 10% phosphoric acid. Acetonitrile was used as Mobile Phase B. The separation was achieved on a gradient method. The reversed phase chromatography was performed in Hypersil BDS C18 5.0 μm, 4.6 × 250 mm column maintained at temperature 35°C. Injection volume was 60 μL. Milli-Q water used as diluent. The mobile phase was pumped at 0.9 mL/min-1. The eluted compounds were monitored at 220 nm. Secondary wavelength of the 263 nm was studied to check any further degradants during the forced degradation studies. New additional degradants Sodium Picosulfate Benzyl alcohol Impurity and N oxide degradations were discussed and studied during the forced degradation to understand the chemical stability of the drug substance.

Chemical Characterization of Lake Togbadji

The present study focused on the chemical characterization of the watercourse of the Togbadji Lake wildlife ranch. The methodological approach followed is as follows: Bibliography review, Sampling campaign. The results obtained were the subject of descriptive statistics, the two-sample Wilcoxon test to determine the impact of different localities on the abundance of microbiological contaminants, a Principal Component Analysis (PCA) with the software R version 3.5.0, in order to group the pollution parameters according to the different levels and sources of contamination. From our results, it is found that the respective average values in dry and rainy seasons for ammonium ions are 0.38 ± 0.16 mg/L and 0.22 ± 0.03 mg/L;for nitrite ions 0.20 ± 0.25 mg/L and 0.02 ± 0.01 mg/L;for nitrate ions 3.72 ± 2.52 mg/L and 7.84 ± 4.91 mg/L;for total Kjeldahl nitrogen 1.27 ± 1.44 mg/L and 1.19 ± 1.49 mg/L;for orthophosphate ions 0.20 ± 0.25 mg/L and 0.02 ± 0.01 mg/L;for total phosphorus 0.04 ± 0.01 mg/L and 0.11 ± 0.23 mg/L;the chemical oxygen demand 93.36 ± 61.73 mg/L of O2 and 89.93 ± 66.11 mg/L of O2 and the biochemical oxygen demand over 5 days 25.50 ± 18.22 mg/L of O2 and 37 ± 33.15 of O2. It emerged that the main sources of pollution in Lake Togbadji are runoff water, discharges of various wastewater from artisanal activities, livestock farming and open defecation.

Understanding the oxidation chemistry of Ti_(3)C_(2)T_(x)(MXene)sheets and their catalytic performances

Transition metal carbides and nitrides(MXenes)nanosheets are attractive two-dimensional(2D)materials,but they suffer from oxidation/degradation issues during storage and/or applications due to their sensitivity to water and oxygen.Despite the great research progress,the exact oxidation kinetics of Ti_(3)C_(2)T_(x)(MXene)and their final products after oxidation are not fully understood.Herein,we systematically tracked the oxidation process of few-layer Ti_(3)C_(2)T_(x) nanosheets in an aqueous solution at room temperature over several weeks.We also studied the oxidation effects on the electrocatalytic properties of Ti_(3)C_(2)T_(x) for hydrogen evolution reaction and found that the overpotential to achieve a current density of 10 mA cm^(-2)increases from 0.435 to 0.877 V after three weeks of degradation,followed by improvement to stabilized values of around 0.40 V after eight weeks.These results suggest that severely oxidized MXene could be a promising candidate for designing efficient catalysts.According to our detailed experimental characterization and theoretical calculations,unlike previous studies,black titanium oxide is formed as the final product in addition to white Ti(IV)oxide and disordered carbons after the complete oxidation of Ti_(3)C_(2)T_(x).This work presents significant advancements in better understanding of 2D Ti_(3)C_(2)T_(x)(MXene)oxidation and enhances the prospects of this material for various applications.

Influence of morphology on basicity of CeO2 and its use in 2-chloroethyl ethyl sulfide degradation

Three CeO_2 samples with different morphologies, i.e., cubes, rods, and spindles, were synthesized and investigated for 2-chloroethyl ethyl sulfide（2-CEES） degradation. The samples were characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, the Brunauer-Emmett-Teller method, and temperature-programmed CO_2 desorption. It was found that morphologies of CeO_2 could strongly affect the surface properties and the 2-CEES degradation activities. The surface basicity and the continuous 2-CEES degradation activity of spindle-like CeO_2 were much better than those of the other CeO_2 samples, although all the samples had identical chemical compositions. That was benefited by the largest surface area, abundant microcracks, and surface oxygen vacancies of the spindle-like CeO_2.

Negative Charge Management to Make Fragile Bonds Less Fragile toward Electrons for Robust Organic Optoelectronic Materials

The operational stability of organic(opto)electronic devices largely depends on the intrinsic stability of organic materials on service.For organic light-emitting diode(OLED)materials,a key parameter of their intrinsic stability is the bond-dissociation energy of the most fragile bond(BDE_(f)).Although rarely involved,many OLED molecules have the lowest BDE_(f) in anionic states[BDE_(f)(−)∼1.6–2.5 eV],which could be a fatal short-slab for device stability.Herein,we separated BDE_(f)(−)from other parameters and confirmed the clear relationship between BDE_(f)(−),intrinsic material stability and device lifetime.Based on thermodynamic principles,we developed a general and effective strategy to greatly improve BDE_(f)(−)by introducing a negative charge manager within the molecule.The manager must combine an electron-withdrawing group(EWG)with a delocalizing structure,so that it can firmly confine the negative charge and hinder the charge redistribution toward fragile bonds.Consequently,the use of this manager can substantially promote BDE_(f)(−)by∼1 eV for various fragile bonds and outperform the effect reported from solely employing EWGs or delocalizing structures.This effect was verified in typical phosphine-oxide and carbazole derivatives and backed up by newly designed molecules with multiple fragile bonds.This strategy provides a new way to transform vulnerable building blocks into robust organic(opto)electronic materials and devices.