Rapid, sensitive colorimetric method for determination of ethinyl estradiol

Area of Science:

• Analytical Chemistry
• Pharmaceutical Analysis

Background:

• Ethinyl estradiol is a widely used synthetic estrogen in various pharmaceutical preparations.
• Accurate quantification of ethinyl estradiol is crucial for ensuring drug efficacy and patient safety.

Purpose of the Study:

• To develop and validate a sensitive colorimetric method for the determination of ethinyl estradiol.
• To assess the method's applicability to pharmaceutical formulations containing ethinyl estradiol.

Main Methods:

• A colorimetric procedure involving the condensation of diazotized 5-chloro-2,4-dinitroaniline with ethinyl estradiol to form an azo dye.
• Measurement of the resulting color intensity at 450 nm using spectrophotometry.

Main Results:

• The method demonstrated linearity up to 10 µg/ml with a lower limit of detection of 1 µg/ml.
• High average recovery (99.6 ± 0.3%) was achieved in synthetic mixtures.
• The method showed no interference from common excipients, vitamins, minerals, or coating materials.

Conclusions:

• The developed colorimetric method is precise, accurate, and suitable for quantifying ethinyl estradiol in pharmaceutical samples.
• The assay is applicable to both single-component and combination progestin-estrogen preparations, including contraceptive and geriatric formulations.