Girum Habte

Determination of toxic heavy metals and speciation of arsenic in seaweeds from South Korea

This study aimed at determining the levels of toxic heavy metals including As, Pb, Cd, Al, Hg and As species, such as, As-III, As-V, MMA, DMA, AsB, and AsC in various edible species of seaweeds from South Korea. ICP-MS was used for determination of As, Pb and Cd, ICP-OES was used for Al, DMA was used for Hg, and LC-ICP-MS was used for As speciation. The analytical methods were validated by linearity, detection limits, precision, accuracy and recovery experiments, obtaining satisfactory results in all cases. From the results toxic heavy metals were found in the decreasing order of: Al>As>Pb-Cd>Hg. Generally concentrations of all analysed heavy metals and both organic and inorganic species of As were very low compared to PTWIs specified by JECFA and EC. Their contribution to the overall intake by the subject seafoods was found very low and thus would not pose any threat to consumers.

Determination of minor and trace elements in aromatic spices by micro-wave assisted digestion and inductively coupled plasma-mass spectrometry

This study aimed at analyzing the concentrations of 23 minor and trace elements in aromatic spices by inductively coupled plasma-mass spectrometry (ICP-MS), after wet digestion by microwave system. The analytical method was validated by linearity, detection limits, precision, accuracy and recovery experiments, obtaining satisfactory values in all cases. Results indicated the presence of variable amounts of both minor and trace elements in the selected aromatic spices. Manganese was high in cinnamon (879.8 μg/g) followed by cardamom (758.1 μg/g) and clove (649.9 μg/g), strontium and zinc were high in ajwain (489.9 μg/g and 84.95 μg/g, respectively), while copper was high in mango powder (77.68 μg/g). On the whole some of the minor and essential trace elements were found to have good nutritional contribution in accordance to RDA. The levels of toxic trace elements, including As, Cd, and Pb were very low and did not found to pose any threat to consumers.

Determination of toxic heavy metals in Echinodermata and Chordata species from South Korea

This study aimed at analysing concentrations of heavy metals including arsenic, lead, cadmium, aluminium and mercury in commonly consumed seafood species belonging to Echinodermata (Anthocidaris crassispina and Stichopus japonicus) and Chordata (Halocynthia roretzi and Styela plicata). The samples were digested by a microwave system and analysed for As, Cd and Pb by inductively coupled plasma mass spectrometer, for Al by inductively coupled plasma-optical emission spectrometer and Hg by Direct Mercury Analyser. The analytical method was validated by determining sensitivity, linearity, precision, spiking recoveries and analysis of the Standard Reference Material (SRM) NIST 1566-b, an Oyster Tissue. Results showed considerably higher accumulation of Al and As in analysed samples, compared to Pb and Cd, while Hg had the lowest contamination. On comparison, the obtained results with the recommended standards by the Food and Agriculture Organization, European Commission and Ministry of Food and Drug Safety of Korea, it was concluded that the analysed seafoods were safe and thus would not pose a threat to consumers.

Elemental profiling and geographical differentiation of Ethiopian coffee samples through inductively coupled plasma-optical emission spectroscopy (ICP-OES), ICP-mass spectrometry (ICP-MS) and direct mercury analyzer (DMA).

This study was aimed to establish the elemental profiling and provenance of coffee samples collected from eleven major coffee producing regions of Ethiopia. A total of 129 samples were analyzed for forty-five elements using inductively coupled plasma (ICP)-optical emission spectroscopy (OES), ICP-mass spectrometry (MS) and direct mercury analyzer (DMA). Among the macro elements, K showed the highest levels whereas Fe was found to have the lowest concentration values. In all the samples, Ca, K, Mg, P and S contents were statistically significant (p<0.05). Micro elements showed the concentrations order of: Mn>Cu>Sr>Zn>Rb>Ni>B. Contents of the trace elements were lower than the permissible standard values. Inter-regions differentiation by cluster analysis (CA), linear discriminant analysis (LDA) and principal component analysis (PCA) showed that micro and trace elements are the best chemical descriptors of the analyzed coffee samples.

Determination of toxic heavy metal levels in commonly consumed species of shrimp and shellfish using ICP-MS/OES

Toxic metal concentrations, including lead (Pb), cadmium (Cd), aluminum (Al), mercury (Hg), and arsenic (As) in edible tissues of different species of shrimp and shellfish consumed in South Korea were analyzed. Analysis was performed using inductively coupled plasma (ICP)-MS) for Pb, Cd and As, ICP-optical emission spectrometry (OES) for Al, and a direct mercury analyzer for Hg. Methods used were validated. Limited variation in heavy metal concentrations between shrimp and shellfish were observed. Al and As concentrations were highest while Hg was lowest. Heavy metal levels found in edible tissues of shellfish and shrimp were below international and local maximum permissible levels for human consumption. The methods used were accurate and reproducible for use in determination of toxic heavy metal levels in seafoods.

Determination of Mineral Elements in Milk Products by Inductively Coupled Plasma-Optical Emission Spectrometry

The determination of mineral elements in milk products is of great importance since their excess or deficiency may affect human health. In this study, calcium, magnesium, potassium, sodium, phosphorus, and iron were determined in milk products from South Korea. The samples were wet-digested by microwave-assisted combustion using nitric acid and hydrogen peroxide, and analyzed by inductively coupled plasma-optical emission spectrometry. The method was validated by sensitivity, linearity, precision, recovery checks, and the analysis of a milk powder certified reference material. The elemental concentrations were similar in the milk products. Calcium and potassium were the most abundant, followed by phosphorus, sodium, magnesium, and iron. All concentrations were comparable to previous values and were within the limits of recommended dietary allowances and tolerable upper levels.

Determination of Radiation Induced Hydrocarbons in Irradiated Camembert and Processed Cheese by GC-MS

Food irradiation processing needs proper control to facilitate consumer assurance, choice, and protection, including accurate detection of irradiated food. This study was aimed at analyzing hydrocarbons induced by gamma and electron beam irradiation in Camembert and processed cheeses. The samples were irradiated at 0, 1, 3, 5, 7, and 10 kGy doses of γ-rays and an electron beam. The induced hydrocarbons were separated on a florisil column and identified by gas chromatography-mass spectrometry (GC-MS). The detected hydrocarbons were pentadecane and 1-tetradecene from palmitic acid, heptadecane and 1-hexadecene from stearic acid, and 8-heptadecene and 1,7-hexadecadiene from oleic acid. The concentrations of the radiation-induced hydrocarbons increased with irradiation dose. Among the induced hydrocarbons, 1-tetradecene and 1,7-hexadecadiene were found to be the major hydrocarbons in the cheese samples. For most irradiation doses, the concentration of hydrocarbons induced by the electron beam was slightly higher than by gamma rays. These hydrocarbons were detected only in irradiated samples at 1 kGy or above, and not in the nonirradiated ones. It was concluded that the detected hydrocarbons were good markers to distinguish irradiated and nonirradiated cheese.

Determination of Essential and Toxic Elements in Tropical Fruit by Microwave-Assisted Digestion and Inductively Coupled Plasma–Mass Spectrometry

ABSTRACT The concentrations of eight essential (Co, Cr, Cu, Mn, Ni, Se, V, and Zn) and five toxic elements (Al, As, Cd, Hg, and Pb) were determined in 457 samples of commonly consumed fresh tropical fruit including bananas (Musa acuminata), kiwi (Actinidia deliciosa), mangos (Mangifera indica), and pineapple (Ananas comosus) from supermarkets from Seoul, Busan, Gangneung, Daegu, Daejeon, and Gwangju, South Korea. The samples were digested by microwave-assisted combustion using HNO3 and H2O2 and determined by inductively coupled plasma mass spectrometry. The Hg concentrations were evaluated by furnace-gold amalgamation direct mercury analysis. The techniques were validated by linearity, limits of detection and quantification, precision, recovery, and the analysis of a NIST-1570a spinach leaves certified reference material. The concentrations of essential elements varied considerably among the tropical fruit. Overall, the tropical fruit was higher in Mn (0.027–13.2 µg/g) and Zn (0.514–2.20 µg/g), while lower in Co (0.002–0.005 µg/g) and V (0.001–0.002 µg/g). The concentrations (µg/g) of toxic elements were 0.001 (kiwi) to 0.003 (mango) for As and Cd, 0.0004 (pineapple) to 0.002 (banana) for Hg, and 0.005 (kiwi) to 0.013 (mango) for Pb. The calculated values of estimated dietary intake, target hazard quotients and hazard indices were lower than one and the safety limits established by World Health Organization. The tropical fruits were therefore safe and did not pose any threat to consumers.

Detection of Hydrocarbons Induced by Gamma and Electron Beam Irradiation in Ground Beef by Gas Chromatography–Mass Spectrometry

This study determined hydrocarbons induced by gamma and electron beam irradiation of ground beef. The samples were irradiated with 0, 2.5, 5, 7.5, 10, 15, and 20 kGy dosages of gamma-rays and an electron beam. The lipid contents were extracted by hexane and the induced hydrocarbons were separated and identified by gas chromatography–mass spectrometry. The analytical method was validated by characterization of detection limits, linearity, precision, and recovery; satisfactory results were obtained in all cases. The major hydrocarbons detected in irradiated ground beef samples were pentadecane and 1-tetradecene from palmitic acid, heptadecane, and 1-hexadecene from stearic acid, and 8-heptadecene and 1,7-hexadecadiene from oleic acid. The induced hydrocarbons were detected at irradiation levels above 2.5 kGy but not in the absence of irradiation. The induced hydrocarbons showed an increase with radiation dosage, but the concentration was slightly higher for gamma rays than for the electron beam. The 1-tetradecene, 8-heptadecene, and 1,7-hexadecadiene were detected as the major hydrocarbons and showed good linearity with irradiation level. It was concluded that these major hydrocarbons are suitable markers to distinguish irradiated and unirradiated ground beef.

Determination of Macronutrients in Spices by Inductively Coupled Plasma-Optical Emission Spectrometry

The concentrations of the macronutrients sodium, potassium, calcium, magnesium, phosphorus, and iron were determined in spices by microwave-assisted digestion with nitric acid and hydrogen peroxide and analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES). The analytical methods were validated by recovery checks and the analysis of spinach leaves Standard Reference Material (NIST-1570a). The concentrations were dependent upon the identity of the spice. Potassium, calcium, and magnesium were the most abundant elements, followed by sodium, iron, and phosphorus. Concentrations of all analyzed elements were comparable to the published literature on spices and met the critical limits of Recommended Dietary Allowances and Tolerable Upper Levels, specified by the Food and Nutrition Board, USA.