Estrogens determination through disposable pipette extraction coupled to ultraviolet spectroscopy and nonlinear pseudo‐univariate calibration: Solving rank deficiency problems

Abstract

AbstractIn this study, the disposable pipette extraction (DPX) approach was employed to prepare water samples containing the hormones 17‐β‐estradiol (beta‐EST), estrone (ETR), estriol (EST), and 17‐α‐ethinylestradiol (17‐EE). Both multivariate and univariate experimental designs were used to optimize the DPX procedure through ultraviolet (UV) and high‐performance liquid chromatography (HPLC). The determination of estrogens in water through UV spectroscopy exhibited rank deficiency, and after trying several strategies, it was possible to suggest that the rank deficiency in the spectra was solved by column augmented matrix strategy afterward complexing the hormones with β‐cyclodextrin, in which the relative concentration recovered by the multivariate curve resolution with alternating least squares (MCR‐ALS) to each hormone was employed in the development of nonlinear pseudo‐univariate calibration models based on support vector machine (SVM) approach. The models were validated through parameters of merit determination and by comparing the models results with those obtained by HPLC. The alternative methodology for the determination of estrogens in water through UV spectroscopy is an environmentally friendly analytical methodology employing less solvent and with high throughput. Moreover, it is not possible to determinate these hormones without using the chemometric approaches, mainly due to the rank deficiency, which needs to be broken to allow for the differentiation between the substances and later modeling.