Fluoride levels in commercially available rice in Ethiopia

Rice (Oryza sativa, Asian; Oryza glaberrima, African) is an important staple food crop in many Sub-Saharan African and Asian countries, so the consumer’s daily bowl of rice needs to be safe and of good quality. The objective of this study was to determine level of fluoride in raw and cooked rice by ion selective electrode. Alkaline fusion was used for sample preparation of six varieties for both the raw rice and rice cooked with tap water and fluoridated water. Fluoride levels ranged from 0.1-5.5 mg/kg in raw rice sample. Rice which was cooked with different fluoride levels of water showed increment depending on the method of cooking. In absorption method of cooking fluoride level was higher than that cooked by excess method and it may be due to the fact that all the fluoride in the water used for cooking by absorption method goes in to the grain while in excess method the remaining water was removed. The employed alkaline fusion procedure was evaluated using spiking method and an acceptable percentage recovery was obtained. A statistical analysis of variance at 95% confidence level for fluoride determination indicated significant difference between the mean of each variety of rice samples. KEY WORDS: Fluoride, Ethiopian rice, Imported rice, Staple food, Cooking methods Bull. Chem. Soc. Ethiop. 2013, 27(2), 179-189.DOI: http://dx.doi.org/10.4314/bcse.v27i2.

METALLIC NUTRIENTS IN ENSET (ENSETE VENTRICOSUM) CORM CULTIVATED IN WOLLISO AND WOLKITE TOWNS IN ETHIOPIA

Enset is an adaptable and drought resistant plant with multiple usages including consumption as co-staple diet in some parts of Ethiopia and has been dubbed “a tree against hunger”. With the plant gaining increased recognition as a food and cash crop, the need for multi-faceted research initiatives appears to be undisputable to preserve its features, maximize its productivity and document changes that would have occurred over the years. The metallic composition of unprocessed corm collected in Wolkite and Wolliso towns in Ethiopia has been investigated. As well as providing information on health benefits or risks, metallic composition may suggest fortification opportunities to improve its nutritive value or that of others and give an insight into temporal alterations. The levels of calcium, magnesium, potassium, iron, zinc, manganese, chromium, cobalt, copper, nickel, cadmium and lead determined with flame atomic absorption spectrometer (FAAS) in digested unprocessed corm samples varied as follows: Ca 36.1–39.1; Mg 24.9–26.9 and  K 14.1–32.2 (mg/g); Zn 11.9–42.3; Cu 1.5–5.2; Co 2.8–10.5; Cr 5.8–7.6; Fe 18.2–54.4; Mn 2–5; Ni 1–4 and Cd 0.6–1.8 (mg/g) with 15.3 μg/g lead being detected in one sample from Wolkite. Method accuracy evaluated as percentage recovery was within 90–110. The levels of metals were higher in samples from Wolliso than those from Wolkite, except for Pb, Mn and Cd. These results indicate that the enset corm, which is low in non-essential nutrients and rich in Ca, Mg, K, Zn and Fe can be recommended as nutritional supplement for deficiencies of Ca, Mg, K, Zn, and Fe

DETERMINATION OF THE LEVELS OF LEAD IN THE ROADSIDE SOILS OF ADDIS ABABA, ETHIOPIA

Contamination of the roadside soils of Addis Ababa city by lead, most likely originationg from vehicular exhaust, has been investigated. To this end, soil samples were collected from 14 roadside sites; i.e., 2 samples for shorter and 5 samples for longer roads. Determination of lead was carried out on a total of 45 samples and a control sample collected from a relatively remote area of the city, Entoto Mountains, which was assumed to be free of anthropogenic lead sources. The levels of lead in all the samples were determined using flame atomic absorption spectrometer. The concentration of lead obtained from majority of the sample sites surpassed the maximum limit of the metal in soil recommended by WHO (100 μg/g). The average concentrations of lead in the roadside soils were found to be 418.6 ± 3.4 μg/g. Similarly, the concentration of lead in the control soil sample was 18.8 ± 0.5 μg/g. Although at present the lead content of the gasoline used in the country is 0.013 g/L, the use of leaded gasoline during the past decades is thought to be responsible for the high concentration of lead in the roadside soils of Addis Ababa

Extraction and spectrophotometric determination of niobium(V) using N-4-chlorophenylcinnamohydroxamic acid and thiocyanate

Bull. Chem. Soc. Ethiop., 4(1), 1-11 (1990)

Determination of Iron(III) with N-phenyicinnamohydidxamic acid and sodium azide by extraction and spectrophotometry

Bu11.Chem.SOC.Ethiop.1(1) 1-8(1987)

Determination of Iron(III) with N-phenyicinnamohydidxamic acid and sodium azide by extraction and spectrophotometry

Bu11.Chem.SOC.Ethiop.1(1) 1-8(1987)

Sample clean-up, enrichment and determination of <i>s</i>-triazine herbicides from southern ethiopian lakes supported using liquid membrane extraction

The liquid membrane extraction method has been employed for selectively extracting trace quantities of <i>s</i>-triazine herbicides in environmental waters collected from lakes Awassa, Chamo and Abbya, located in close proximity to the agricultural farms in Southern Ethiopia. In liquid membrane extraction, the uncharged triazine compounds from the flowing donor solution diffuse through a porous poly(tetrafluoroethylene) (PTFE) membrane, containing a water immiscible organic solvent. The <i>s</i>-triazine molecules are then irreversibly trapped in the stagnant acidic acceptor phase since they become protonated. Using both di-n-hexylether and n-undecane membrane solvents, <i>s</i>-traizine herbicides were extracted and low detection limits of about 1 ng/L have been obtained by extraction of three liters of sample solution spiked with 0.1 g/L of each triazine. Residues of atrazine and terbutryn ranging in concentration from 0.02 to 0.05 g/L have been successfully determined

Evaluation of the effect of various drying techniques on the composition of the psychoactive phenylpropylamino alkaloids of khat (<i>Catha edulis</i> Forsk) chewing leaves

The study demonstrated that by freezing or drying under different conditions, cathinone could be detected in the khat (<i>Catha edulis</i> Forsk) samples that have been harvested for more than four months. Freeze drying or freezing in the refrigerator (-20 ^oC) yielded more than 73% of cathinone. Air drying, sun drying or oven drying at 60 ^oC resulted in a cathinone composition of 57%, 42% and 36%, respectively. The study confirmed that, freshly harvested tender leaves of khat contained exclusively of cathinone but upon sun drying, part of it decomposes to cathine and norephedrine leaving cathinone as a major component. Thus it is wrong to assume that sun drying the leaves can result complete conversion of cathinone to cathine and norephedrine. Furthermore, the results of the study confirmed that it was possible to preserve khat samples for longer periods after freeze drying or deep freezing without significant loss of cathinone.DOI: http://dx.doi.org/10.4314/bcse.v27i3.