Análise de contaminantes em amostras de água aplicando sistemas aquosos bifásicos (SAB) como método de extração

Abstract

The study of the extraction/partition for determination of partition coefficient (K) of the hormones 17α-ethinylestradiol (EE2), levonorgestrel (LV), gestodene (GD), cyproterone acetate (AC) and estradiol valerate (VE) obtained from birth control pills was carried out in aqueous two-phase system (ATPS) upper phase with later determination by ultraviolet-visible spectrophotometry (UV-Vis). The partition parameters evaluated for the system were: pH (3.00; 5.00; 7.00; 9.00 and 11.00); ATPS forming electrolytes (Na2SO4, Li2SO4.H2O, MgSO4.7H2O, Na2C4H4O6.2H2O, Na3C6H5O7.2H2O) and polymers (PEO1500, L64 and L35); tie-line length (TLL); temperature (5.00; 15.0; 25.0; and 40.0 ºC); and mass ratio between top and bottom phases (mBP/mTP: 1/1, 2/1, 3/1, 4/1 and 5/1). This evaluation was carried out through univariate and multivariate optimization, using experimental design. It was observed, for the first time, interactions of TLL and polymer with temperature, directly influencing the partition of hormones in ATPS. The best conditions obtained for all hormones was L35 + Na2SO4 + H2O, at pH = 3.00, TLL = 64.06% w/w, T = 25 ° C and mBP/mTP = 5/1. This condition of hormone extraction was applied to samples of drinking water, lake and river water and filtered water from a water treatment plant and showed promising results, given the high analytical signals of the hormones obtained from the upper phase of the ATPS. The validation of the sample preparation method using ATPS and amoxicillin quantification from the UPLC-MS/MS was also performed. The linear range determined was 0 – 750 µg L-1, with a quantification limit (LQ) of 30 µg L-1. Precision and accuracy were evaluated at three concentration levels (30, 250 and 750 µg L-1), reaching coefficients of variation less than 3% and recoveries greater than 92%.