ABSTRACT
The presence of arsenic in ground waters of many countries has been a subject of global concern due to its toxicity. Primary sources of arsenic are geogenic, i.e. weathering and erosion of rocks and soils containing arsenic. This paper presents a rapid method for determination of arsenic in solid geological samples by wavelength dispersive X-ray fluorescence spectrometer. To achieve the best LLD (lower limit of detection), the most intense X-ray fluorescence line Kα1,2 is preferably used for determination of elemental concentrations because it pertains to the most probable transition. But the greatest challenge in arsenic estimation is the serious line overlap of AsKα1,2 lines with the equi-energy PbLα1,2 lines. By using the conventional line overlap correction methods, uncertainty and detection limits in arsenic determination are degraded to an unacceptable degree in samples which contains high lead and low arsenic concentrations. The proposed method bypasses the line overlap issue in employing a novel concept of arsenic-lead concentration equivalence factor for the cumulative peak of AsKα1,2 and PbLα1,2 fluorescence lines. The constancy of this factor for all geological matrices facilitates arsenic determination in samples universally irrespective of matrix elements. For the method validation, 22 international certified reference materials have been analysed and the results proved to be propitious wherein only one value out of 22 determinations showed relative error more than 20% of the certified values. This attests to the high accuracy of the proposed method which can effectively determine arsenic below 5 mg/kg in the presence of high lead concentration up to 1000 mg/kg.
ABSTRACT
OBJECTIVE: To assess the complete nutritional profile and identification of bioactive components present in the hydro-ethanolic extract of Alocasia indica tuber. METHODS: The proximate composition and vitamins were assessed from fresh tissue while mineral content was detected from the ash using inductively coupled plasma atomic spectrophotometer. For gas chromatography analysis, the tubers were shade dried and extracted with ethanol using Soxhlet apparatus for 72 h. The extract was dried using rotary evaporator and analyzed for active components. RESULTS: The tuber was rich in carbohydrate, but marginal in protein content. However, it showed moderate amount of dietary crude fibre, very low fat content and sufficient source of ascorbic acid and alpha-tocopherol. The tuber was also found to contain all the essential micro and macro mineral elements. It especially served as a good source of potassium and calcium while moderate source of iron, zinc and magnesium. Gas chromatography analysis also revealed the presence of several components of biological value in the ethanolic fraction of the extract. The extract was basically found to be a good source of poly-unsaturated fatty acids and some amount of polyphenols. CONCLUSIONS: All the major compounds identified and characterized by spectroscopic method were of biological significance. Besides, the tuber also possesses high calorific value and source for low fat and moderate dietary fibre which is essential for maintaining proper health. Moreover, the mineral content of the tuber can be used as supplement for combating malnutrition especially among rural folk and the vitamin content can serve as good source of natural antioxidant. Thus identification of a good number of important compounds from Alocasia indica tubers can focus on its use for future therapeutic purpose apart from maintaining general health.
ABSTRACT
A hypoxanthine (Hx) biosensor based on immobilized xanthine oxidase (XO) as the bio-component was developed and studied for the rapid analysis of fish (sweet water and marine) and goat meat samples. The biosensor was standardized for the determination of Hx in the range of 0.05 to 2 mM. Crosslinking with glutaraldehyde in presence of BSA as a spacer molecule was used for the method of immobilization. One layer of gelatin (10%) was applied over the immobilized enzyme layer to reduce the leaching out of enzyme from the membrane (cellulose acetate) matrix. The optimum pH of the immobilized system was determined to be 8.5 at 25 degrees C instead 7.0-7.2 for free enzyme system. Km and Vmax values were determined for the immobilized system. The developed sensor was applied to determine the amount of Hx present in fish and meat over a period of time. The stability of the enzyme immobilized membrane was also tested over a period of 30 days.
