Browsing by Author "Alresawum, Yoseph"

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    Laser Induced Breakdown Spectroscopy (LIBS) Coupled with Multivariate Chemometric Method for Characterization and Quality Control of Ethiopian Coffee and Herbal Medicines
    (Addis Ababa University, 2016-04) Alresawum, Yoseph
    In this researches seven Ethiopian export quality coffee, their ten mixtures, ten commonly used medicinal plants and their two mixtures were analyzed. The method of analysis we used is the LIBS technique. Atomic and ionic lines of Zn, Cu, Mg, Al, Ca, K , Mn Fe, P and Na were used for characterization of coffee and medicinal plant samples. Using the most relevant emission signals of LIBS, an attempt was made in order to discriminate the samples of coffee and their mixtures using Principal Component Analysis. We applied PCA for characterization of Ethiopian coffee, according to their geographical origin first by using forty nine atomic and ionic lines then by using all calcium and magnesium lines. We investigate several ranges and identify the use of these models on a specific range for a higher accuracy; accordingly we can able to characterize the coffee samples by using two lines of magnesium and two lines of calcium and finally we optimize our characterization by using only one line of calcium and one line of magnesium. By taking a sample at a time we have shown the capability of LIBS coupled with PCA for discrimination of coffee samples from their mixtures and this is useful for inspection of adulteration of coffee. Nutrient elements of ten Ethiopian herbal medicines and their mixtures promoting health advancing effect and practiced in local medicine were determined using LIBS technique. The LIBS analysis revealed the presence of many nutrient elements such as copper, zinc, carbon, manganese, phosphorous, calcium, magnesium, iron, sodium and potassium. In this study we also tried to correlate the elemental compositions in the plants with their biological effects then, by using principal component analysis we clustered the herbal medicines with similar elemental compositions. Finally we demonstrated the capability of LIBS for monitoring the change in elemental compositions of the mixtures of herbal medicines