Conjugations of Carbaryl in Insects

<p>The conjugation of carbaryl and its initial breakdown products in insects has been examined. Houseflies, blowflies and grass grubs were dosed with [3 H] carbaryl and the water-soluble metabolites examined by a combination of paper chromatographic and ionophoretic techniques. These revealed the presence of 1-naphthyl dihydrogen phosphate, 1-naphtyl hydrogen sulphate and 1-naphthyl Beta-D-glucoside in the extracts, as well as at least seven other unidentified substances, probably including the phosphate, sulphate and glucoside conjugates of oxidation products of carbaryl. The conjugation of 1-naphthol, one of the primary metabolites of carbaryl, was examined in greater detail in flies and grass grubs. Isotope dilution and paper chromatographic analyses of extracts of insects dosed with [14 C]1-naphthol revealed the presence of the phosphomonoester, sulphate, and glucoside conjugate of 1-naphthol, but phosphodiester and glucosiduronic acid conjugates could not be detected. A new metabolite of 1-naphthol was present in extracts of dosed flies. This new metabolite, and also the corresponding p-nitrophenol metabolite, was isolated form extracts of flies fed with the parent phenols and characterised as a new conjugate, the Beta-D-glucoside 6-(dihydrogen phosphate). Some of the properties of this new conjugate were determined. 1-Naphthyl Beta-D-glucoside 6-phosphate probably accounted for one of the unidentified carbaryl conjugates.</p>

Conjugations of Carbaryl in Insects

<p>The conjugation of carbaryl and its initial breakdown products in insects has been examined. Houseflies, blowflies and grass grubs were dosed with [3 H] carbaryl and the water-soluble metabolites examined by a combination of paper chromatographic and ionophoretic techniques. These revealed the presence of 1-naphthyl dihydrogen phosphate, 1-naphtyl hydrogen sulphate and 1-naphthyl Beta-D-glucoside in the extracts, as well as at least seven other unidentified substances, probably including the phosphate, sulphate and glucoside conjugates of oxidation products of carbaryl. The conjugation of 1-naphthol, one of the primary metabolites of carbaryl, was examined in greater detail in flies and grass grubs. Isotope dilution and paper chromatographic analyses of extracts of insects dosed with [14 C]1-naphthol revealed the presence of the phosphomonoester, sulphate, and glucoside conjugate of 1-naphthol, but phosphodiester and glucosiduronic acid conjugates could not be detected. A new metabolite of 1-naphthol was present in extracts of dosed flies. This new metabolite, and also the corresponding p-nitrophenol metabolite, was isolated form extracts of flies fed with the parent phenols and characterised as a new conjugate, the Beta-D-glucoside 6-(dihydrogen phosphate). Some of the properties of this new conjugate were determined. 1-Naphthyl Beta-D-glucoside 6-phosphate probably accounted for one of the unidentified carbaryl conjugates.</p>

Synthesis and Characterization of Caprolactam- based Ionic Liquids as Green Solvents

Aims: To synthesize and characterize six caprolactam-based ionic liquids (CPILs) by combination of caprolactam with different organic and inorganic Brønsted acids that can be utilized for lipid extraction from microalgae. Study design: Experimental design include quantitative and qualitative. Place and duration of study: The study was done at Department of Chemistry & Biochemistry, School of Sciences and Aerospace Studies, Moi University (Kenya) between November 2020 and May 2021. Methodology: Six CPILs were prepared through a simple neutralization reaction between Caprolactam and Brønsted acids such as Hydrochloric acid (HCl), Methane sulphonic acid (CH3SO3H), Trifluoromethanesulphonic acid (CF3SO3H), Acetic acid (CH3CO2H), Trifluoroacetic acid (CF3CO2H), and Sulfuric acid (H2SO4). The first three acids were used in the synthesis of CPILs for the first time. The chemical structures of the synthesized CPILs were characterized by Fourier transform infrared and Raman spectroscopy. The densities and viscosities were measured at 20 oC using the weight (pycnometer) and capillary viscometer (Oswald) methods, respectively. Results: All the CPILs were insoluble in hexane and had high miscibility with water and methanol. Fourier transform infrared and Raman spectra of the CPILs were compared with that of free Caprolactam. The characteristic absorption bands of the synthesized compounds showed a big shift in position and/or intensity (compared to caprolactam), indicating the formation of the CPILs. The results showed that both the density and viscosity increased with the molecular weight of the anion - except in Caprolactamium hydrogen sulphate (CPSA)- which could be due to the strong interactions between the cation and anion resulting from the dimerization between hydrogen sulphate anions. Conclusion: The hydrophilic nature of the CPILs indicated by high miscibility with polar solvents (water and methanol) indicates that they are suitable for the dissolution of cellulose of microalgae cell wall and thus could result in high lipid extraction efficiency. Further studies should therefore utilize the synthesized CPILs in lipid extraction from microalgae.

A Novel Quinoxaline-Rhodamine Conjugate for a Simple and Efficient Detection of Hydrogen Sulphate Ion

This work presents the development of a quinoxaline and rhodamine conjugate system that acts as a colorimetric chemosensor for hydrogen sulfate (HSO4−) ions in methanol media. This sensor has been characterized both theoretically and experimentally. The detection limits for HSO4− are small as 0.71 µM and 3.8 µM for the absorption and emission experiments, respectively. The effectiveness of the probe in recognizing HSO4− both in gel and solid phase is evaluated as well. Thus, this works presents a simple strategy to detect the environmental HSO4− pollutant event at tiny concentrations.

Synthesis of 3-alkyl-1,2,3-triazol-1-ium hydrogen sulphate derivatives

An array of 3-alkyl-1,2,3-triazol-1-ium hydrogen sulphate derivatives was obtained from the reaction between some 1,4-disubstituted-1,2,3-triazoles and H2SO4 through a simple protocol in good yields. The molecular structure of a triazolium salt (R1 = PhCH2, R2 = CH2O(4-CHO)C6H4) was unambiguously determined from X-ray diffraction studies, showing a remarkable triazole N3–H bond.

Quality by Design Approach for Development and Validation of Stability Indicating RP-HPLC Method for Fosaprepitant Dimeglumine

Quality by design approach has been used to develop simple, rapid, sensitive gradient RP-HPLC stability indicating method for fosaprepitant dimeglumine and its related impurities. The chromatographic method has been developed by using symmetry shield RP-18 (250 mm × 4.6 mm; 5 μm) column maintained at column temperature of 20 ºC. The mobile phase-A consisted of water and acetonitrile (800:200, v/v), added 2 mL of orthophosphoric acid and 0.17 g of tetrabutylammonium hydrogen sulphate. The mobile phase-B consisted of water and acetonitrile (200:800, v/v), added 2 mL of orthophosphoric acid and 0.17 g of tetrabutylammonium hydrogen sulphate. Gradient program was executed as time (min)/% MP-A: 0/80, 3/80, 12/40, 20/20, 24/20, 25/80, and 30/80. The UV detection was carried out at wavelength 210 nm and 20 μL of sample was injected. Sample cooler was maintained at 5 ºC. Stability of fosaprepitant dimeglumine sample was investigated in different stress condition as acid, base, oxidation, thermal, humidity and photolytic. The method was developed in two phases, screening and optimization. During the screening phase, the most suitable stationary phase, organic modifier, and solvent were identified based on the behaviour of each stationary phase with fosaprepitant dimeglumine and its impurities using each buffer and solvent. Total 18 experiments were performed to find out the best experimental condition. The optimization was done for secondary influential parameters like column temperature, gradient program, using six experiments to examine multifactorial effects of system suitability parameters and generated design space representing the robust region. A verification experiment was performed within the working design space and the model was accurate. Drug showed unstable behaviour under acid, base, oxidation, thermal, and humidity conditions. Apripetant was found as major degradation impurity. The method was validated as per ICH guideline for specificity, limit of detection (LOD), limit of quantitation (LOQ), linearity, accuracy, precision, ruggedness and robustness. Correlation coefficient is about 0.999 for all impurities, recovery is between 90% to 103% at all level. LOD value of each impurity is less than 0.01% w/w. DOE statistically based experimental designs proved to be an important approach in optimizing selectivity-controlling parameters for the organic impurities determination in FD API. The method was found to be specific, linear, accurate, precise and robust. The peak purity test results confirmed that the fosaprepitant dimeglumine peak was homogenous in all stress samples and the mass balance was found to be more than 99%, thus proving the stability indicating power of the method. Present method is found to be suitable for routine analysis in quality control laboratory.

Silica-immobilized ionic liquid Brønsted acids as highly effective heterogeneous catalysts for the isomerization of n-heptane and n-octane

Metal-free imidazolium-based ionic liquid (IL) Brønsted acids 1-methyl imidazolium hydrogen sulphate [HMIM]HSO4 and 1-methyl benzimidazolium hydrogen sulphate [HMBIM]HSO4 were synthesized.