NISCAIR Online Periodicals Repository Collection: IJCT Vol.13(5) [September 2006]

Diacetylmonoxime-(p-anisyl)-thiosemicarbazone as a new chromogenic reagent for determination of thallium

Tue, 29 Aug 2006 22:58:59 GMT

Title: Diacetylmonoxime-(p-anisyl)-thiosemicarbazone as a new chromogenic reagent for determination of thallium

Authors: Varghese, Anitha; Khadar, A M A

Abstract: A simple and sensitive derivative spectrophotometric method has been developed for the determination of thallium(III) using a newly synthesized reagent diacetylmonoxime-(p-anisyl)-thiosemicarbazone in acetic acid medium. The molar absorptivity and Sandell’s sensitivity of the coloured species are 5.610⁴L mol^-1cm^-1 and 3.6 ng cm^-2, respectively. Beer’s law is obeyed between 0.25 and 2.60 g mL^-1 of Tl(III) at 460 nm. The stoichiometry of the complex was found to be 1:2 (metal: ligand). Calibration graphs were derived by measuring first order derivative amplitudes at 425 and 505 nm. The metal ions like Cu(II), Cd(II), Pb(II), Zn(II) and Bi(III) which are usually associated with thallium containing samples do not interfere. The developed procedure has been successfully applied for the trace level determination of thallium in minerals, alloys, urine, soil and water samples.

Page(s): 470-475

Application of chitosan and alginate in treating waste water containing heavy metal ions

Tue, 29 Aug 2006 22:58:59 GMT

Title: Application of chitosan and alginate in treating waste water containing heavy metal ions

Authors: Qin, Yimin; Shi, Bingbing; Liu, Jingjie

Abstract: The use of sodium alginate and chitosan in treating waste water containing heavy metal ions has been studied in this paper. The effect of the concentration and ratio of chitosan and sodium alginate, treatment temperature and time on the efficiency of Cu(II) ion removal was investigated. Results showed that when used in combination, sodium alginate and chitosan were effective in removing Cu(II) ions from waste water. The treatment was applied to other heavy metal ions such as cadmium, lead and silver ions, and the treatment efficiency was compared. Results showed that when used in combination, the separation of polymeric absorbents from waste water is better than when chitosan and sodium alginate are used alone.

Page(s): 464-469

Reversible inhibition of polyphenol oxidase from apple using L-cysteine

Tue, 29 Aug 2006 22:58:59 GMT

Title: Reversible inhibition of polyphenol oxidase from apple using L-cysteine

Authors: Gacche, R N; Shete, A M; Dhole, N A; Ghole, V S

Abstract: Alternate strategies for prevention of enzymatic browning of fruits and vegetables are required by food industries due to restrictions and several negative health attributes of sulphites, which are effective inhibitors of enzymatic browning reaction. These reactions result mostly from polyphenol oxidase (PPO). The present study was conducted to evaluate the antioxidant and PPO inhibitory potential of L-cysteine. Studies have revealed that with increase in concentration of L-cysteine there was corresponding decrease in the rate of browning reaction and the activity of PPO. The kinetic study indicates that PPO inhibition by L-cysteine is non-competitive. The results suggest that the L-cysteine is a time bound inhibitor of PPO, since its highest concentration (5 mM) gives protection up to 4 h having no further effect on the rate of browning reaction in apple juice. The assessment of radical-scavenging ability of L-cysteine demonstrated that it has high affinity towards a stable free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH^·).

Page(s): 459-463

An easy spectrophotometric determination of selenium using azure B as a chromogenic reagent

Tue, 29 Aug 2006 22:58:59 GMT

Title: An easy spectrophotometric determination of selenium using azure B as a chromogenic reagent

Authors: Mathew, Mendalin; Narayana, Badiadka

Abstract: A simple, rapid and sensitive spectrophotometric method has been developed for the determination of trace amounts of selenium in water samples, soil, plant materials and human hair. The proposed method is based on the reaction of selenium with potassium iodide in acidic medium to liberate iodine. The liberated iodine bleaches the violet colour of azure B, which is measured at 644 nm. This decrease in absorbance is directly proportional to selenium concentration. Beer’s Law was obeyed in the range 2.0-10.0 µgmL^-1 of selenium. The molar absorptivity, Sandell’s sensitivity, quantitation limit and detection limit of the method were found to be 0.9473 10⁵ L mol^-1 cm ^-1, 8.33 10^-4 µg cm^–2, 0.070 µgmL^-1 and 0.023 µgmL^-1, respectively. The proposed method has been successfully applied to the determination of selenium in various samples.

Page(s): 455-458