New, simple and validated UV-spectrophotometric methods for the estimation of sodium usnate in preparations

Ivana Savić, Goran Nikolić, Ivan Savić, Saša Zlatković, Dragiša Djokić


New, simple, cost effective, accurate and reproducible UV-spectrophotometric methods were developed and validated for the estimation of sodium usnate in pharmaceutical preparations. Sodium usnate was estimated at 290 nm in water and phosphate buffer (pH 3):methanol (11:20 V/V). Beer’s law was obeyed in the concentration range of 0.1–5 μg·cm−3 (r = 0.997) in water and 1–12 μg·cm−3 (r = 0.999) in the phosphate buffer:methanol. The apparent molar absorptivity and Sandell’s sensitivity coefficient were found to be 3.16×104 dm3·mol−1·cm−1 and 11.58 ng·cm–2/0.001 A in water and 3.72×104 dm3·mol−1·cm−1 and 9.83 ng·cm–2/0.001 A in phosphate buffer:methanol, respectively, indicating the high sensitivity of the proposed methods. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.0721 and 0.2163 μg·cm–3 in water and 0.163, 0.489 μg·cm−3 in phosphate buffer:methanol, respectively. The proposed methods were successfully applied for the determination of sodium usnate in pharmaceutical preparations. The results demonstrated that the procedure is accurate, precise and reproducible (R.S.D. < 2 %).


sodium usnate; spectrophotometry; method validation; pharmaceutical preparations

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P. A. Ark, A. T. Bottimi, J. P. Thompson, Sodium usnate

as an antibiotic for plant diseases, Plant disease Report,

, 200-203 (1960).

M. Cocchietto, N. Skert, P.L. Nimis, G. Sava, Review

on usnic acid, an interesting natural compound, Naturwissenschaften,

, 137–146 (2002).

S. Huneck, I. Yoshimura, Identification of Lichen Substances,

Springer, 1996.

K. Ingolfsdottir, G. Chung, V. Skulason, S. Gissurarson,

M. Vilhelmsdottir, Antimycobacterial activity of lichen

metabolites in vitro, E. J. Pharm. Sci., 6, 141–144


M. Cakić, G. Nikolić, N. Nikolić, M. Stanković, FTIR

spectra of usnic acid dihydrate natrium salts and its deuterated

analogs, III Simpozijum Savremene tehnologije

i privredni razvoj, Proceedings, Leskovac, OHT-3, 74


S. Shibata, Y. Miura, Antibacterial effects of lichen substances,

Jpn. Med. J., 1, 518–521 (1948).

M. Stanković, S. Stanković, Z. Đorđević, S. Đorđević,

Process for obtaining natrium salt of (+)-usnic acid, Pat.

Yu 43978 (1989).

C. Coiffard, L.J.M. Coiffard, F. Peigne, and Y. De

Roeck-Holtzhauer, Effect of pH on Sodium Usnate

Thermostability in Dilute Aqueous Solutions, Arch.

Pharm. pharm. Med. Chem. 331, 128–132 (1998).

C. Coiffard, L. J. M. Coiffard, Y. De Roeck-Holtzhauer,

Photodegradation Study of Sodium Usnate Solution:

Influence of pH, Drug Development and Industrial

Pharmacy, 25 (12), 1295–1299 (1999).

The European Agency for the Evaluation of Medicinal

Products. ICH Topic Q2B Note for Guideline on Validation

of Analytical Procedures: Methodology GPMP/

ICH/281/95, 1996.

United States Pharmacopoeia, Validation of Compendial

Methods, 26th edition, Pharmacopoeial Convention

Inc., Rockville, MD, 2003. pp. 2439–2442.

S. Bolton, Pharmaceutical Statistics: Practical and

Clinical Application, 3rd ed., Marcel Dekker, New

York, 1997, pp. 216–264.

J. C. Miller, J. N. Miller, Statistics for Analytical Chemistry,

nd ed.,Wiley, New York, 1984, pp. 83–117.

Y. J. Wei, K. A. Li, S. Y. Tong, A linear regression method

for the study of the Coomassie brilliant blue protein

assay, Talanta, 43, 1–10 (1996).



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