Determination of essential and toxic trace elements in biological materials, mostly foodstuffs, was grow to the need at this present time. Earlier workers [1-3] have reported that trace metal contents of sure foods, mostly fish should be contaminated with non-residential effluents and wastes discharged into oceans, lakes, coastal waters, etc. Different species of fish [4-6] shall uptake heavy metals in their tissue, which shall in some approach toxic levels. Some regarding the investigators [7-12] have reported significantly high grades of cadmium and arsenic in some species of fish. However, the investigation of DE GOEIJ [13] and GUINN [14] have shown that there is no significant difference of these grades of sure trace elements, like arsenic, cadmium than those in unpolluted areas.
Whether or not fish shall be contaminated shall depend on the chemical shape regarding the element and its concentration within the surrounding medium, microbiological activity within the marine environment, texture regarding the sediment, kind and age regarding the fish, etc. However, there exists still insufficient data available in Bangladesh for toxic metals like arsenic, cadmium, etc. It is strongly believed that this read shall consequently be a best help for Bangladesh's economy in view of quality assurance for trade as well as the health, well-being and benefit of her people. This cardboard presents details on the concentration of arsenic, chromium, selenium and zinc in some varieties of fish and also describes briefly the chemical procedure followed. The instrumental neutron activation analysis INAA of such elements as As, Cr, Cd, Zn and Cu in pet organs and fish tissues is difficult due to the fact that regarding the 24Na and 86Br activities developed on irradiation.
This is due to the fact that the photopeaks of radioactive products of these elements are masked, particularly by the Compton continuum regarding the high 24Na matrix activity, thus posing difficulty not only in handling but also within the computation regarding the peak regions from the -ray spectra. This difficulty has necessitated post-irradiation chemical separation of isotopes of interest. This cardboard describes such a scheme for determination of seven trace elements As, Cr, Se and Zn in biological materials. Samples collection and irradiation. Eight varieties of common marine fish, selected in accordance with their public taste for Bangladeshi near coastal belt in most try and cost, namely, Coilia neglecta, Cirrhinna reba,Johnius argantus, Harpondon nehereus, Setipinna phasa and Lepturacanthus savala were collected from the coastal belt regarding the Bay of Bengal and sun-dried subsequent to removal of their internal organs, head, skin, and tails.
The dried samples were then chopped into pieces together with the aid of a stainless steel knife steam cleaned. Only the edible muscle tissue samples were used for analysis. The sample pieces were dried at 105o-110oC in an stove until a constant mass was obtained hard weight. The dried samples were ground, sieved and thoroughly mixed in a stainless steel rotating drum for 100 hours to make a homogeneous powder. The sample powder was finally preserved in simple and hard polyethylene bottles.
Portions regarding the samples 200-300 mg each were heat-sealed in polyethylene bags and irradiated along with a known no. of MA-A-2, the fish flesh homogenate standard of IAEA within the CIRUS reactor at Bhabha Atomic Studies Center, Trombay, Bombay, India, at a flux of about. two NH3, HCl, HNO3, HClO4 and acetic acid; 3 Na2SO3 solution:. 4 mg or cm3? 4 NaOH pellets; 5 thioacetamide; six H2O2; seven BaCl2 =0. 2M solution in water; 7 NH4H2PO4= 1M solution; 8 hydroxylamine hydrochloride NH2OH.
Each regarding the irradiated samples was allowed to cold for 4-5 days to enable the decay of short-lived isotopes and also to reduce the 82Br and 24Na activities. About 10 mg carrier for each regarding the element was added to a 100 ml round-bottomed flask and the irradiated sample was carefully opened and emptied into it. Then, the sample was digested in Bethge's apparatus with a mix of seven cm3 concentrated nitric acid and 3 cm3 of concentrated perchloric acid till a liquid remained within the flask. Chemical separation and determination of metal. After the digestion was completed, the distillates were, evaporated to dryness on a sand bath to remove nitric acid, and leached with conc.
HCl 10 cm3 and preserved to be combined together with the filtrates from chromium and selenium precipitation. two Determination of chromium: 5 cm3 HClO4 was added to the residue within the flask and drops of conc. HCl added to the warm solution to distil of CrO2Cl2. The distillate was collected in 10 ml sodium hydroxide solution 1N. 5 cm3 BaCl2 solution followed by addition of 2-3 drops of H2O2.
BaCrO4 was digested in a h2o bath and was filtered, dried and counted for 51Cr. The filtrate was combined together with the distillate from decomposition step. Cr is oxidized to Cr VI by HClO4. H2Cr2O7 + 5 HCl 2CrO2Cl2 + 2H2O reddish vapor. CrO2Cl2 + 2NaOH Na2CrO4 +2HCl yellow distillate.
Na2CrO4 + BaCl2 BaCrO4 + 3 NaCl. 3 Determination of selenium: To the residue remaining within the flask 20 ml of conc. HCl was added and the volume kept at 50 ml. To the warm solution 4-5 cm3 Na2SO3 solution was added and digested in a h2o bath for two hour. The precipitated Se metal was filtered, dried and counted for 75Se.
This filtrate also was combined together with the distillate from the decomposition step. MCl2 + SO2 +2H2O M metal + 2HCl + H2SO4. 4 Determination of arsenic: The acidity regarding first distillate, together with the filtrates from chromium precipitation and selenium precipitation mixed together, was adjusted to 1M HCl and two ml of a 1% solution of thioacetamide was added to the boiling solution. This was digested in a h2o bath. Precipitates of sulfides of As were filtered off, washed, dried and counted 76As.
CH3CSNH2 + H2O CH3CONH4 + H2S. CH3CONH2 + H2O CH3COONH4. 5 Determination of zinc. The filtrate from 4 was evaporated to dryness in a boiling h2o bath followed by addition of drops of conc. HNO3 until the ammonium salts were completely destroyed.
To this was added two cm3 1M NH4H4PO4 solution. The pH regarding the solution was then adjusted to seven and it was heated for a little minutes. The mix was then kept in a h2o bath for two hour. The precipitates obtained were filtered off, washed, dried and counted for 65Zn. ZnCl2 + NH4H2PO4 ZnNH4PO4 + 2HCl [M= Zn].
The samples and the standards were counted on a 45 cm3 HPGe detector connected to a 4096 channel pulse-height analyzer Ortec PCA-MCA card. The energies in keV chosen for the evaluation regarding the peak regions were: 76As 26. 4 h, E=657 keV since, the photopeaks of 122Sb 561keV interfered with photopeak 76As at 559 keV, the 657 keV photopeak was chosen to measure 76As photopeak region ? 51Cr 27. Accuracy and precision. Experiments were initially carried out creating use of radioactive tracers and the corresponding carriers to evaluate the recoveries.
The yields were within the section of 93% to 98%. The accuracy regarding the method was evaluated by analyzing homogenate fish flesh IAEA Standard Reference Material, MA-A-2. Our conclusions values in g or g are in good agreement together with the IAEA certified values. RESULTS AND DISCUSSION. The As, Se, Cr and Zn concentrations determined within the fish species are presented in.
The values are expressed in g. The section of concentrations located within the fish samples are As 2. These variations are likely to be due to the migratory nature and feeding habits regarding the different species of fish. Normally, the grades of As 4 ng or ml, Se 0. 01 ng or ml have been located to be barely little in sea-water [15], but the grades of these metals as located in fish samples below investigation are higher.
This is due to the tendency of different species of fish to concentrate sure elements within the tissue higher than surrounding medium. The mean concentrations of arsenic, selenium, chromium and zinc in fish are 3. 007 g or g and 59 g or g, respectively. Using neutron activation, HAMILTON AND MINSKI [16] reported the mean values for As in fish as 2. Up to 174 ppm was located in prawns from the coastal waters of Britain [17] and 42 ppm in shrimp from the southeastern.
coastal waters regarding the United States [18]. Fish wheat for person consumption has been. reported [19] to contain 1. 8 ppm Se and tuna food median grades as high as 5. 2 ppm hard basis [20].
High natural Se grades in tuna [21] and marine mammals [22]. Reveal ocean h2o contains as little as 10 g or l of Zn at the surface [23] consequently coastal seawater usually contains 0. 5-2 g or l of Zn like a result of river inputs and sewage outfalls [24-26]. Two Table two and 3 are deleted. Taking seven g of fish as the maximum consumption [27] per person per day for Chittagong and coastal regions of Bangladesh, it is estimated that the average intake of arsenic, selenium, chromium and zinc through fish is 3.
The daily intake of arsenic is barely low[28]. gives the comparison regarding the grades of arsenic, selenium, chromium and zinc in fish by different researchers in different countries. The present read indicates that the radiochemical separation scheme should be used. for the isolation nuclides with mutually interfering -rays e. , 75Se, with 203Hg at 265 keV.
Within the case of 76As, due to the interference of 122Sb, at 559 keV, we have chosen the fewer sensitive 657 keV peak for computation of arsenic. Eight tropical marine fish species collected from the Bay of Bengal were analyzed sequential to assess the position of trace toxic elements in this food item consumed by the population of Bangladesh. The conclusions indicate that the concentrations of these elements are many below the toxic levels.
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