Browsing by Author "Kawa, Yahaya Kudus"

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Evaluation of Brands of Ascorbic Acid Tablets on the Market After Exposure to Sunlight and Temperature in Sierra Leone
(2026-03-02) Kawa, Yahaya Kudus
This study evaluated the quality, stability, and regulatory status of selected vitamin C tablet brands marketed in Freetown under different storage conditions. An experimental study design was employed involving ten (10) brands of vitamin C tablets purchased from registered pharmacies in the Western Area Urban between October and November 2021. Baseline physicochemical analyses were conducted, after which samples were exposed to sunlight and elevated temperature (40 ± 1 °C) for six months, alongside a control stored under recommended conditions. Quality assessment was carried out in accordance with British Pharmacopoeia (BP) 2022 and USP standards, including identification by Thin Layer Chromatography, assay of ascorbic acid content, uniformity of dosage units, friability, and disintegration testing. Results showed that friability values for all samples remained within acceptable limits (≤1%), indicating adequate mechanical strength. Significant degradation of ascorbic acid content was observed following exposure to sunlight and elevated temperature. At baseline, 7 out of 10 samples (70%) complied with BP assay specifications, while after six months of exposure, only 3 samples (30%)—C2, C5, and C7—remained within specification under both stress conditions. One sample (C9) consistently demonstrated extreme assay failure (≤58% of label claim) and failed the uniformity of dosage units’ test, with acceptance values ranging from 41.87 to 56.5. Additionally, 5 out of 10 products (50%) were unregistered, highlighting gaps in regulatory compliance within the pharmaceutical supply chain. Prolonged exposure to sunlight and high temperature reduces the chemical stability and dosage uniformity of vitamin C tablets, even when physical strength remains acceptable. The findings highlight the need for stronger regulatory oversight, enforcement of product registration, improved storage practices and increased public awareness to ensure the quality and safety of pharmaceutical products.
Extraction, optimization and characterization of crude polysaccharides from Artemesia Mongolica
(Academic Journals, 2016-11-30) Kawa, Yahaya Kudus
In this study, the extraction conditions of polysaccharides of Artemisia mongolia (PAM) were optimized and their molecular weight, weight distribution, composition and antioxidant activities of the polysaccharides investigated. The degree of polymerization of fructan-oligosaccharides 2-8 was separated by thin layer chromatography (TLC) with good results. Polysaccharides were extracted from the leaves of A. mongolia and the effects of the extraction parameters (extraction temperature, extraction time and water to raw material ratio) were optimized under optimal extraction combinations. Based on the study, the maximum yield of polysaccharides (17.38%) was obtained at an extraction temperature of 76.90°C, extraction time of 1.33 h and water-to-raw material ratio of 4.00 ml/mg. The yield of polysaccharides was largely dependent on the extraction parameters. Four isolated fractions of the polysaccharides were further characterized using high-performance liquid chromatography. Using TLC analysis, the degree of polymerization of fructan-oligosaccharides 2-8 was successfully separated. High A. mongolia antioxidant polysaccharide with antioxidant activity of 351.3 sc/g was obtained at optimized incubation temperature of 70.37°C, extraction time of 1.45 h and water-to-raw material ratio of 2 ml/mg. Key words: Artemisia Mongolia, crude polysaccharide, antioxidant activity, response surface methodology, box-Behnken design
Physical, chemical and bacterial analysis of drinking water: Kakua Chiefdom, BO district, Sierra Leone
(Academic Journals, 2016-01-31) Kawa, Yahaya Kudus
Water makes the difference between living and non-living things, base on this there is a strong need to look at the chemistry, to make sure that it is free from contamination because of chemical reaction that take place in the living cell. In the case of this study, it is critical to determine the quality of the water supplied, because of the chemical reaction. This study analyzes 10 representative well water systems for 18 quality parameters in Kakua Chiefdom of Bo District, Sierra Leone. The study note among others, well-water total dissolved solids (TDS), turbidity, electrical conductivity (EC), coliform and nitrate (NO3-), in the region that are fairly high. The incidence of coliform in well waters is highest in April and those iron (Fe2+) and nitrate in May. The Dipha street well is amongst the most contaminated and TDS, Non-faecal and fluoride (F-) have the highest scores in a three-category plot along wells. Correlation analysis among the water chemistry shows an interesting results; ranging strong positive (R=1.0) to strongly negative (R=-1.0). Key words: Physico-chemical, parameter chemical parameters, bacteriological parameters, water molecule.