Masoud Shariati-Rad; Mohsen Irandoust; Farahnaz Niazi
Volume 1, Issue 2 , June 2014, , Pages 93-97
Abstract
A simple and rapid spectrophotometric method for the determination of nitrite in water and soil preparation samples has been developed. Determination of nitrite is based on diazotization of p-nitro aniline with nitrite and subsequent coupling with 4-amino-3-hydroxynaphthalene-1-sulfonic acid in hydrochloric ...
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A simple and rapid spectrophotometric method for the determination of nitrite in water and soil preparation samples has been developed. Determination of nitrite is based on diazotization of p-nitro aniline with nitrite and subsequent coupling with 4-amino-3-hydroxynaphthalene-1-sulfonic acid in hydrochloric acid. The factors affecting the reaction i.e. concentration of p-nitro aniline, concentration of 4-amino-3-hydroxynaphthalene-1-sulfonic acid and concentration of the hydrochloric acid solution were studied and optimized using central composite design. The analysis of the results of experimental design showed that for obtaining higher signals the values of the above factors should be as 2.0×10-4, 5.0×10-4 and 1.33 M, respectively. The reaction yields a product with an absorption maximum at 302 nm. Beer’s law is obeyed in the range 0.10-2.00 mgL-1 of nitrite. The molar absorptivity of the product was found to be 6.74×104. The method was applied successfully to the determination of nitrite in water and soil samples. Relative standard deviation of the method was below 2%.
Masoud Shariati-Rad; Mohsen Irandoust; Somayyeh Amri; Mostafa Feyzi; Fattaneh Ja’fari
Volume 1, Issue 1 , March 2014, , Pages 6-12
Abstract
A method was developed for removal, preconcentration and spectrophotometric determination of trace amounts of methyl red based on SiO2-coated Fe3O4magnetic nanoparticles. The influence of pH, dosage of adsorbent and contact time on the adsorption of dye was explored by central composite design. The kinetic ...
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A method was developed for removal, preconcentration and spectrophotometric determination of trace amounts of methyl red based on SiO2-coated Fe3O4magnetic nanoparticles. The influence of pH, dosage of adsorbent and contact time on the adsorption of dye was explored by central composite design. The kinetic data were analyzed based on the Langmuir and Freundlich adsorption isotherms. The Langmuir model was fitted well to data and the maximum monolayer capacity q max of 49.50 mg g−1 was calculated. The results showed that desorption efficiencies of higher than 99% can be achieved in a short contact time of 3 min and in one step elution using 2.0 mL of 0.1 mol L−1 NaOH. The magnetic nanoparticles were washed with deionized water and reused for two successive removal processes with removal efficiencies more than 90%. Then desorbed dye was determined spectrophotometrically. The calibration curve was linear in the range of 0.025–0.250 mg L−1 of dye with a correlation coefficient of 0.9922. The relative standard deviations obtained upon application of the method to the real samples were lower than 0.7%. A preconcentration factor of the method was 50.
