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E-Journal of Chemistry
Volume 2 (2005), Issue 1, Pages 6-14

Spectrophotometric Determination of Chromium in Water, and Pharmaceutical Samples Using 1-Naphthol

K. Suvardhan,1 S. Ramanaiah,2 K. Suresh Kumar,1 D. Rekha,1 Umayur Bhagan,3 G. R. K. Naidu,4 G. Krishnamurthy Naidu,5 B. S. Sastry,6 and P. Chiranjeevi1

1Environmental Monitoring Laboratory, Department of Chemistry, S. V University, Tirupati-517502, India
2Department of Geology, S. V University, Tirupati-517502, India
3Hindu College, M.S University, Nagarkoal, Tamil Nadu, India
4Department of Environmental Sciences, S. V University, Tirupati-517502 .A.P., India
5Department of Pharmacy, S.V. Govt. Polytechnic, Tirupati-517501 .A.P., India
6Department of Pharmaceutical Sciences, Andhra Univeristy, Vishakapatnam-530003.A.P., India

Received 8 November 2004; Accepted 14 December 2004

Copyright © 2005 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Facile and sensitive spectrophotometric methods for the determination of trace and ultra trace amounts of chromium (VI) are described. 4-aminoantipyrine (APP) reacts with 1-naphthol (NPL) in presence of oxidising agent potassium dichromate in acidic medium to produce red coloured product having λmax of 485 nm. The molar absorptivity and Sandell's sensitivity were 2.07x104 l mol-1 cm-1 and 0.00240 μg/cm2 respectively. The colour is stable for more than 6 h. The system obeys Beer's law in the range, 2-18 μg for determination of chromium (VI). The detection limits of chromium (VI) is 0.048 μg mL-1. The method is highly reproducible and has been applied to the analysis of chromium in synthetic, natural water samples and pharmaceutical preparations and the results compared favourably with the reported method.