Magnetic ionic liquids as versatile extraction phases for the rapid determination of estrogens in human urine by dispersive liquid-liquid microextraction coupled with high-performance liquid chromatography-diode array detection

In this study, a rapid and straightforward approach based on magnetic ionic liquids (MIL) as extraction phases and dispersive liquid-liquid microextraction (DLLME) was developed to analyze the hormones estriol, 17-beta-estradiol, 17-alpha-ethynylestradiol, and estrone in human urine samples. This is the first report of an application of manganese-based MILs compatible with HPLC to extract compounds of biological interest from urine samples. The hydrophobic MILs trihexyltetradecylphosphonium tetrachloromanganate (II) ([P-6,P-6,P-6,P-14 (+)](2)[MnCl4 (2-)]) and aliquat tetrachloromanganate (II) ([Aliquat(+)](2)[MnCl4 (2-)]) were employed and the optimized extraction conditions were comprised of 5 mg of MIL ([P-6,P-6,P-6,P-14 (+)](2)[MnCl4 (2-)]), 5 mu L of methanol (MeOH) as disperser solvent, and an extraction time of 90 s at sample pH 6. The analytical parameters of merit were determined under optimized conditions and very satisfactory results were achieved, with LODs of 2 ng mL(-1) for all analytes, determination coefficients (R (2)) ranging from 0.9949 for 17-beta-estradiol to 0.9998 for estrone. In addition, good results of method precision were achieved with the intraday (n = 3) varying from 4.7% for 17-beta-estradiol to 19.5% for estriol (both at 5 ng mL(-1)) and interday precision (evaluated at 100 ng mL(-1)) ranging from 11.4% for estrone to 17.7% for 17-alpha-ethynylestradiol and analyte relative recovery evaluated in three real samples ranged from 67.5 to 115.6%. The proposed DLLME/MIL-based approach allowed for a reliable, environmentally friendly and high-throughput methodology with no need for a centrifugation step.