High throughput liquid phase thin film microextraction of estrogens by solvent-loaded polyvinylidene fluoride membrane sheet.

A polyvinylidene fluoride (PVDF)-based membrane was developed for high-throughput liquid phase thin film microextraction (LP-TFME) of estrone (E1) and 17β-estradiol (E2) in aqueous and biological samples, followed by quantification using high-performance liquid chromatography with ultraviolet detection (HPLC-UV). The film was fabricated via a two-step casting (TC) process combined with phase inversion and characterized using field emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), nitrogen adsorption-desorption analysis, and overall porosity measurements. Extraction and desorption conditions were systematically optimized, yielding the following parameters: 1-octanol as the organic solvent, 16 % (w/v) NaCl, stirring rate of 1600 rpm, pH 8, temperature 25 °C, extraction time 35 min, methanol as the desorption solvent, and desorption time 15 min. The method achieved high-throughput efficiency, processing samples at a rate of 0.78 minutes per sample during the extraction-desorption cycle through 64-well plate technology. Under optimized conditions, the method demonstrated linear calibration ranges of 0.5-150 μg L⁻¹ for aqueous samples and 10-150 μg L⁻¹ for both plasma and urine samples for E1 and E2. Limits of detection (LODs) were determined as 0.16 μg L⁻¹ (aqueous) and 3.30 μg L⁻¹ (plasma and urine) for both analytes. Relative standard deviations (RSDs) ranged from 6.87 % to 8.71 %, while enrichment factors reached 46.25 for E2 and 56.19 for E1, highlighting the method's precision and sensitivity.