Simultaneous determination of three naturally occurring estrogens in environmental waters by high-performance liquid chromatography

Facile preparation of reduced graphene oxide/ZnFe2O4 nanocomposite as magnetic sorbents for enrichment of estrogens

Reduced graphene oxide/ZnFe₂O₄ (rGO/ZnFe₂O₄) nanocomposite was facile prepared and applied as magnetic sorbent for the extraction of estrogens including 17β-estradiol, 17α-estradiol, estrone and hexestrol from water, soil, and fish samples prior to HPLC analysis. The rGO/ZnFe₂O₄ nanocomposite was characterized by scanning electron microscope, Fourier transform-infrared spectroscopy, X-ray diffraction, and vibrating sample magnetometer. The experimental parameters affecting the efficiency of magnetic solid-phase extraction (MSPE) including the amount of material, extraction time, pH, temperature, desorption solvents, desorption time, and desorption solvent volume were investigated respectively. With the developed method, good linearity was observed in the range of 0.05-500 ng/mL with the correlation coefficients (R²) between 0.9978 and 0.9993. The limits of detection (S/N = 3) and limits of quantification (S/N = 10) were achieved at 0.01-0.02 ng/mL and 0.05 ng/mL, respectively. The enrichment factors were calculated as the range of 241-288. Using rGO/ZnFe₂O₄ nanocomposite as the sorbent, the developed MSPE followed by HPLC analysis, was applied to analysis of estrogens in river water, soil and fish samples. The method has the potential application in the extraction and preconcentration ultra trace compounds in complex matrices, such as environmental and biological samples.

Development of Simultaneous Derivative Spectrophotometric and HPLC Methods for Determination of 17-Beta-Estradiol and Drospirenone in Combined Dosage Form

Simple, rapid spectrophotometric, and reverse-phase high performance liquid chromatographic methods were developed for the concurrent analysis of 17-beta-estradiol (ESR) and drospirenone (DRS). The spectrophotometric method was based on the determination of first derivative spectra and determined ESR and DRS using the zero-crossing technique at 208 and 282 nm, respectively, in methanol. The linear range was 0.5–32.0 µg·mL⁻¹ for DRS and 0.5–8.0 µg·mL⁻¹ for EST. The limit of detection (LOD) values were 0.14 µg·mL⁻¹ and 0.10 µg·mL⁻¹ and limit of quantification (LOQ) values were 0.42 µg·mL⁻¹ and 0.29 µg·mL⁻¹ for ESR and DRS, respectively. The chromatographic method was based on the separation of both analytes on a C₁₈ column with a mobile phase containing acetonitrile and water (70 : 30, v/v). Detection was performed with a UV-photodiode array detector at 279 nm. The linear range was 0.08–2.5 µg·mL⁻¹ for DRS and 0.23–7.5 µg·mL⁻¹ for EST. LOD values were 0.05 µg·mL⁻¹ and 0.02 µg·mL⁻¹ and LOQ values were 0.15 µg·mL⁻¹ and 0.05 µg·mL⁻¹ for ESR and DRS, respectively. These recommended methods have been applied for the simultaneous determination of ESR and DRS in their tablets.