Netai Mukaratirwa Muchanyereyi

Miconazole/Hydrocortisone (HCA) cream is a pharmaceutical formulation developed as a combination of three major components (HCA, miconazole nitrate [MCN] and chlorocresol [CHL]). In some instances, reference monographs used for referencing the quantification of pharmaceutical molecules focus on individual analysis of molecules. Therefore, there is need to develop, optimize and validate methods that simultaneously separate constituents of a combined formulation. In this study, a method for the separation of HCA, MCN and CHL in miconazole/HCA cream was developed by investigating the effect of mobile phase, stationary phase, wavelength and gradient program on the separation of HCA, MCN and CHL in miconazole/HCA cream. A 10 mM ammonium acetate (AAC) buffer pH 5.0 was used. Acetonitrile was used as the organic modifier. An injection volume of 10 µL was used on a C18, 15 cm × 4.6 mm Zorbax. The optimum conditions for reverse phase liquid chromatography were obtained as follows: injection volume (10 µL), column temperature (30°C), flow rate (1 mL/min), gradient elution program: 0 min, 60AAC:40ACN; 4 min, 60AAC:40ACN; 9 min, 5AAC:95ACN; 13 min, 5AAC:95ACN using a C18 stationary phase, UV detector, 5 µm stationary phase pore size and post run of 3 min.

The study seeks to determine the most significant factors affecting arsenic and chromium enrichment using novel P-ZrO2CeO2ZnO nanoparticles/alginate beads in order to minimize the total number of runs needed to successfully run the experiment. The effects of interactions between factors were also evaluated so that the optimum conditions which are not affected by the other factors are chosen for the experiments. The most significant factors on arsenic and chromium enrichment were screened for by using a half-factorial design, followed by the optimization of significant factors using the full-factorial design, and the interaction between factors was determined using ANOVA and interaction plots. The most significant factors for chromium recovery were sample volume, eluent flow rate, and sorbent dosage. For both chromium and arsenic recovery, interactions occurred between sample volume, dosage, and pH. The optimum conditions chosen for the experiment that gave favourable results for both metal ions were sample volume 5 mL, dosage 40 mg, pH = 7 and eluent flow rate 1 mL/min. This study showed that a preliminary screening step for the most significant factors for arsenic and chromium enrichment helps to reduce the number of total runs, and for the same experiment interactions between factors were present; hence, it is necessary to take this into account during the experimental design.

This research article presents a comparative study of the adsorption properties of Moringa oleifera biomass using Pb2+ ions as test analyte. The investigated parameters which affected the adsorption process were the effect of pH, initial concentration, adsorbent dose, contact time, and temperature. The comparison of adsorption process was evaluated in the pH range of 3 to 8, concentration range from 5 to 20 ppm, temperature varied from 25 to 80°C, variation of contact time from 15 to 80 min, and dose of the adsorbent from 0.3 to 1.2 g. The results obtained showed that a high adsorbent dose is required for high adsorption capacity. The pH of 7 was most effective with temperature set at 25°C and contact time of 60 min. The Temkin, Dubunin-Radushkevich, Langmuir and Freundlich isotherms were applied and fitted well to the data and values of the parameters of these isotherm equations were calculated. The Langmuir isotherm proved to be the overall best isotherm. The adsorbent surface functional groups were identified with Fourier Transform Infrared (FTIR) spectroscopy. The maximum adsorption capacity obtained was 98% for seed, 96% for blended, 94% for pods, and 92% for leaves. Better thermodynamic and kinetic properties were obtained with the seeds and the blended samples. In total, these results indicate that the blended moringa biosobent can be employed as a low-cost biosorbent for the removal of lead ions from water. Key words: Biosorption, Moringa oleifera biomass, adsorption isotherms, lead ions.

Sweet sorghum (Sorghum bicolor (L.) moench), a crop that is grown by subsistence farmers in Zimbabwe was used to extract silica gel in order to assess its possible use as a raw material for the production of silica-based products. The gel was prepared from sodium silicate extracted from sweet sorghum bagasse ash by sodium hydroxide leaching. Results show that maximum yield can be obtained at pH 5 and with 3 M sodium concentration. The silica gel prepared at optimum pH 5 had a bulk density of 0.5626 g/cm3 and anestimated porosity of 71.87%. Silica gel aged over 10 h had improved moisture adsorption properties. X-ray fluorescence (XRF) determinations show that the silica content in the ash is 40.1%. Characterization of sweet sorghum ash and silica gels produced at pH 5, 7 and 8.5 by Fourier Transform Infrared spectroscopy gave absorption bands similar to those reported by other researchers.Transmission electron micrographs show that silica prepared under optimum conditions is amorphous and consisted of irregular particles. Sweet sorghum proved to be a potential low cost raw material for the production of silica gel. Key words: Silica gel, sweet sorghum, extraction, ash, bagasse, X-ray powder diffraction (XRD).