scholarly journals Microwave-Assisted Acid Extraction of Selenium from Medicinal Plants Followed by Electrothermal Atomic Absorption Spectrometric Determination

2010 ◽  
Vol 93 (2) ◽  
pp. 694-702 ◽  
Author(s):  
Nida Fatima Kolachi ◽  
Tasneem Gul Kazi ◽  
Jameel Ahmed Baig ◽  
Ghulam Abbas Kandhro ◽  
Sumaira Khan ◽  
...  
Keyword(s):  
Medicinal Plants ◽  
Atomic Absorption ◽  
Certified Reference Materials ◽  
Electrothermal Atomic Absorption Spectrometry ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Acid Extraction ◽  
Optimization Strategy ◽  
Microwave Assisted ◽  
Significant Difference

Abstract A simple and rapid microwave-assisted extraction (MAE) of selenium (Se) from medicinal plants was investigated using different concentrations of nitric acid and hydrochloric acid, sample mass, heating time, microwave energy, and plant particle size. The optimization strategy was carried out using multivariate methodologies. Electrothermal atomic absorption spectrometry was used to determine Se. The accuracy of the optimized procedure was evaluated by using certified reference materials with certified values for Se and a microwave-assisted acid digestion (MD) method for comparative purpose. No significant difference was observed (P > 0.05) when comparing the values obtained by the proposed MAE and MD methods (paired t-test). Under the optimum operating conditions, the LOD obtained from the standard calibration curve was 0.012 g/L for Se. The average RSD of the MAE method varied between 4.05 and 7.53 (n 6). The proposed method was successfully applied for the determination of Se in medicinal plants used as remedies for cancerous and infection diseases.

scholarly journals Modification of Cassava Starch Using Lactic Acid Hydrolysis in The Rotary-UV Dryer to Improve Physichocemical Properties

2018 ◽  
Vol 156 ◽  
pp. 01018 ◽  
Author(s):  
Siswo Sumardiono ◽  
Bakti Jos ◽  
Denny Firmansyah ◽  
Rahmi Hidayatunajah ◽  
Isti Pudjihastuti
Keyword(s):  
Lactic Acid ◽  
Acid Hydrolysis ◽  
Wheat Flour ◽  
Uv Light ◽  
Import Substitution ◽  
Cassava Starch ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Modified Starch ◽  
Significant Difference

Food security should be supported in an effort to utilize local products into import substitution products. Cassava starch has the potential to be developed into semi-finished products in the form of flour or starch which does not contain gluten but can inflate large baking process, potentially as a substitute for wheat flour-the main ingredient for making bread. The characteristic of the starch is influenced by the type of starch composition and structure. Natural starch has physicochemical properties i.e. a long time cooking and pasta formed hard. These constraints allow us to modify cassava starch by a combination of lactic acid hydrolysis and drying with rotary UV system. Modified cassava starch is expected to be used as a substitute for wheat flour. The aim of the research which is a combination of lactic acid hydrolysis and drying using a rotary UV system is to examine the optimum operating conditions in the drying process of starch hydrolysis with parameter the physicochemical and rheological properties of modified cassava starch. The initial process study is to hydrolyze cassava starch using lactic acid. Furthermore, hydrolyzed cassava starch is then dried using UV light in the rotary dryers system. There are a variety of changing variables, i.e. time of irradiation cassava starch-lactic acid hydrolysis products in the rotary UV light and air drying temperature. The research results show that modified starch has a better characteristic than the natural starch. From the analysis, the best point of swelling power, solubility and baking expansion is consequently 15.62 g/g; 24.19 %; 2.21 ml/gr. The FTIR result shows that there is no significant difference of the chemical structure because the starch modification only change the physical characteristics. From the SEM analysis, we can know that the size of the starch’s granule changes between the natural starch and the modified starch..

scholarly journals Determination of Chromium in Biological Material by Electrothermal Atomic Absorption Spectrometry Method

2012 ◽  
Vol 56 (4) ◽  
pp. 585-589 ◽  
Author(s):  
Agnieszka Nawrocka ◽  
Józef Szkoda
Keyword(s):  
Atomic Absorption Spectrometry ◽  
Atomic Absorption ◽  
Certified Reference Materials ◽  
Graphite Furnace ◽  
Electrothermal Atomic Absorption Spectrometry ◽  
Absorption Spectrometry ◽  
Magnesium Nitrate ◽  
Spectrometry Method ◽  
Total Chromium

Abstract Procedure for determination of chromium in biological materials by Zeeman graphite furnace atomic absorption spectrometry method using a Perkin-Elmer spectrometer equipped with hollow-cathode lamp at 357.9 nm was developed. The samples of animal tissues, food, and feed were digested in muffle furnace at 450ºC. The ash was dissolved in 1 N hydrochloric acid and the final solution was diluted in 0.2% nitric acid. Magnesium nitrate (1%) was used as a matrix modifier. The method was validated in terms of basic analytical parameters. The mean recoveries of chromium was 84.4% for muscle, 79.0% for canned meat, and 80.2% for feed, and analytical detection limit was 0.003 μg/g. Certified reference materials were used for analytical quality assurance. The proposed analytical procedure is well adapted for monitoring chromium content in food and feedstuffs. Content of total chromium in the tested samples (animal muscles and liver) was low and was situated in the range of 0.031-0.101 mg/kg (muscles) and 0.047-0.052 mg/kg (liver).

scholarly journals A Multi-Response Optimization for Isomerization of light Naphtha

2019 ◽  
Vol 8 (11) ◽  
pp. 3921-3933
Keyword(s):  
Octane Number ◽  
Maximum Yield ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Optimization Strategy ◽  
Yield Data ◽  
Isomerization Process ◽  
Response Optimization ◽  
Reactor Temperature ◽  
Benzene Content

Isomerization process is considered one of the main processes used to produce high octane rating gasoline with improved environmental conditions and less emissions. The main keys of performance in isomerization units are the product yield, paraffin isomerization number (PIN) and octane number (RON). In this article we present a multi-response optimization strategy for an industrial naphtha continuous isomerization-process that aims to maximize RON, PIN and yield. Data of 53-runs including feed compositions as well as operating conditions; reactor temperature, benzene content, liquid hour space velocity, feed PIN, hydrogen to hydrocarbon ratio, feed octane number, C7+ content, inlet reactor temperature and iC5/C5P ratio are collected from a refinery company over a period of two months to test the effect of each variable and their interaction over each response individually using analysis of variance (ANOVA). Model reduction is applied for the three models in order to exclude any insignificant data and improve the model’s accuracy. Finally, the optimum operating conditions for the process are selected using numerical optimization in Design Expert 11 by comparing with the real industrial data runs to give the maximum yield, PIN and RON which are 99.992, 122 and 86 respectively. Benzene content is selected to be 1.807 wt%, reactor temperature;143oC, LHSV; 0.882 h-1 , feed PIN; 64.611, H2 /HC; 0.07, feed RON; 74.408, C7+; 4.06 wt%, inlet reactor temperature; 116oC and iC5/C5P ratio 45.768.

The Characterization of Rhenium by Atomic-Absorption Spectroscopy in Nitrous Oxide-Acetylene Flames: The Analysis of Organorhenium Compounds

1971 ◽  
Vol 25 (5) ◽  
pp. 539-541 ◽  
Author(s):  
David F. Tomkins ◽  
C. W. Frank
Keyword(s):  
Nitrous Oxide ◽  
Organic Solvent ◽  
Atomic Absorption ◽  
Atomic Absorption Spectroscopy ◽  
Operating Conditions ◽  
Optimum Operating ◽  
Absorption Analysis ◽  
Inorganic Acids ◽  
Absorption Characteristics

This investigation of the atomic-absorption characteristics of rhenium included studies of optimum operating conditions, detection limits, interferences from various inorganic acids, and the effect of organic-solvent ratios on absorption. Atomic-absorption analysis of some organorhenium complexes are also described.

scholarly journals Determination of Mercury in Sewage Sludges by Slurry Sampling Electrothermal Atomic Absorption Spectrometry

2002 ◽  
Vol 85 (1) ◽  
pp. 25-30 ◽  
Author(s):  
Ignacio López-García ◽  
Mateo Sánchez-Merlos ◽  
Jesús Arroyo-Cortez ◽  
Manuel Hernández-Córdoba
Keyword(s):  
Atomic Absorption ◽  
Certified Reference Materials ◽  
Graphite Furnace ◽  
Electrothermal Atomic Absorption Spectrometry ◽  
Absorption Spectrometry ◽  
Slurry Sampling ◽  
Fast Heating ◽  
Conventional Pyrolysis ◽  
Atomic Absorption Spectrometric

Abstract An electrothermal atomic absorption spectrometric procedure was developed for the determination of mercury in sewage sludge, in which the samples were suspended in a solution containing hydrofluoric and nitric acids. Silver nitrate (4%, m/v) and potassium permanganate (3%, m/v) were incorporated as matrix modifiers, and aliquots were directly introduced into the graphite furnace. A fast-heating program with no conventional pyrolysis step was used. The detection limit for mercury in a 50 mg/mL suspension was 0.1 μg/g. Calibration was performed by using aqueous standards. An analysis of certified reference materials confirmed the reliability of the procedure.

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