Determination of Melatonin Hormone in Bulk Form, Tablets and Human Serum by Square-Wave Cathodic Adsorptive Stripping Voltammetry

✍ Scribed by A. M. Beltagi; P. Y. Khashaba; M. M. Ghoneim

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 139 KB
• Volume: 15
• Category: Article
• ISSN: 1040-0397
• DOI: 10.1002/elan.200390136

✦ Synopsis

Abstract

Melatonin hormone plays an important role in many distinct physiological functions. A fully validated, sensitive and reproducible square‐wave cathodic adsorptive stripping voltammetric procedure was described for determination of melatonin in bulk form, tablets and human serum. The procedure was based on the reduction of the adsorptive hormone onto a hanging mercury drop electrode. Reduction behavior of melatonin was studied in both Britton‐Robinson (pH 2–11) and acetate (4.5–5.5) buffers. Acetate buffer of pH 5.0 was found reasonable as a supporting electrolyte for assay of the drug. The square‐wave cathodic adsorptive stripping voltammogram of melatonin showed a single well‐defined peak at −1.45 V (vs. Ag/AgCl/KCl~s~) using an accumulation potential of −0.65 V. This peak may be attributed to the reduction of CO double bond of the amide functional group of the reactant molecule. A mean recovery for 1×10^−8^ M melatonin in bulk form followed 30 s accumulation of 98.87%±0.78 and a detection limit of 3.13×10^−10^ M were achieved. The proposed procedure was successfully applied for the determination of the drug in tablets and human serum with mean recoveries of 97.68%±0.57 and 101.67%±0.85, respectively. A detection limit of 8.80×10^−10^ M was achieved for the determination of the drug in human serum. Results of the proposed method were comparable and coincided with those obtained by reported method. Vitamin B~6~ and common excipients, which are co‐formulated with melatonin, did not interfere. Also the effect of some interfering compounds such as serotonin, tryptophan and 5‐hydroxytryptophan on the determination of melatonin in human serum was studied, and all have no significant effect on the assay recovery.