Supported liquid membrane extraction of 17ß- estradiol
A sample purification and enrichment technique involving the use of supported liquid membrane (SLM) has been developed for the selective extraction of 17b- estradiol and its metabolites, namely 17b-estriol and estrone in various biological matrices and water. The biological matrices in which extraction was done included bovine kidney and liver tissues, milk and urine. The liquid membrane used to trap these compounds was made of 5% tri-n-octylphosphine oxide (TOPO) dissolved in a mixture of di-nhexylether and n-undecane (1:1, v/v). Separation and detection of the analytes obtained after SLM enrichment was done by liquid chromatography-electrospray mass spectrometry (LC-ESI-MS). The extraction efficiencies (E) for 1 ng/L estradiols mixture spiked in various biological matrices were in the order of 61–80%, 52–74%, 67–89% and 61–82% for kidney tissue, milk, urine and liver tissue, respectively. For spiked water sample, the extraction efficiencies were of the order 82–96% from a 1 ng/L sample mixtures. LC-ESI-MS gave the detection limits of 0.3 ng/L, 1.8 ng/L and 2.4 mg/L for 17bestradiol, estrone and 17b-estriol, respectively.