Aqueous solubilities of estrone, 17β-estradiol, 17α-ethynylestradiol, and bisphenol A

The solubilities of three estrogenic hormonessestrone, 17 beta-estradiol, and 17 alpha-ethynylestradiol - and the industrial pollutant bisphenol A were measured in water, dilute acid and alkali ( pH 4 and 10, respectively), and aqueous KNO3 (0.01 mol . L-1 and 0.1 mol . L-1). The concentrations of saturated solutions, after equilibration at (25.0 +/- 0.5) degrees C with excess solid for 4 days, were determined by HPLC. Six replicate results were obtained for each solute-solvent pair: the coefficient of variation was in most cases < 5 %. The solubilities in pure water with standard deviations were estrone (1.30 +/- 0.08) mg . L-1, 17 beta-estradiol (1.51 +/- 0.04) mg . L-1, 17 alpha-ethynylestradiol (9.20 +/- 0.09) mg . L-1, and bisphenol A (300 +/- 5) mg . L-1. The solubility of each of the hormones was unchanged between pH 4 and pH 7 but was greater at pH 10. At pH 7, the hormones became progressively less soluble as the ionic strength increased from 0.0 to 0.1 mol . L-1. By contrast the solubility of bisphenol A was essentially the same under all of the experimental conditions tested.