A Simple Spectrophotometric Method for the Trace Determination of Zinc in Some Real, Environmental, Biological, Pharmaceutical, Milk and Soil Samples Using 5,7- Dibromo-8-hydroxyquinoline

  • M. Tazul Islam Laboratory of Analytical Chemistry, Department of Chemistry, University of Chittagong, Chittagong-4331, Bangladesh.
  • M. Jamaluddin Ahmed Laboratory of Analytical Chemistry, Department of Chemistry, University of Chittagong, Chittagong-4331, Bangladesh.

Abstract

A very simple, ultra-sensitive and highly selective non-extractive spectrophotometric method for the determination of trace amount of zinc using 5,7-dibromo-8-hydroxyquinoline (DBHQ) has been developed. DBHQ reacts in a slightly acidic solution (0.000001-0.000007 M H2S04) with zinc to give a pale-yellow chelate, which has an absorption maximum at 391 nm. The reaction is instantaneous and absorbance remains stable for over 24 hrs. The average molar absorption coefficient and Sandell's sensitivity were found to be 1.62 x 105 L mol -1 cm -1 and 10 ng cm-2 of Zn, respectively. Linear calibration graphs were obtained for 0.02-4 mg L-1 of Zn having detection limit of 5 µg L-1 and RSD 0 - 2%. The stoichiometric composition of the chelate is 1:2 (Zn : DBHQ). A large excess of over 50 cations, anions and some common complexing agents (such as chloride, azide, tartrate, EDTA, oxalate, SCN- etc) do not interfere in the determination. The method was successfully used in the determination of zinc in several Standard Reference Materials (alloys and steels) as well as in some environmental waters (potable and polluted), biological samples (human blood and urine), soil samples, milk samples, pharmaceutical samples and complex synthetic mixtures.The results of the proposed method for biological samples were comparable with AAS and were found to be in excellent agreement.The method has high precision and accuracy (s = ± 0.01 for 0.5 mg L-1).

Published
Dec 2, 2013
How to Cite
ISLAM, M. Tazul; AHMED, M. Jamaluddin. A Simple Spectrophotometric Method for the Trace Determination of Zinc in Some Real, Environmental, Biological, Pharmaceutical, Milk and Soil Samples Using 5,7- Dibromo-8-hydroxyquinoline. Pakistan Journal of Analytical & Environmental Chemistry, [S.l.], v. 14, n. 1, p. 15, dec. 2013. ISSN 2221-5255. Available at: <http://pjaec.pk/index.php/pjaec/article/view/220>. Date accessed: 18 oct. 2017.