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  • For membrane protected SPE the choice of sorbent is crucial


    For membrane protected μ-SPE, the choice of sorbent is crucial because it determines the extraction efficiency. Up to now, many porous materials, such as carbon based sorbents [1,[3], [4], [5], [6]], ethylsilane or octadecylsilane modified silica (C2 or C18) [7,8], polymeric materials [[9], [10], [11]], mesoporous silica [12], zeolites [13], and metal organic frameworks (MOFs) [[14], [15], [16]], have been selected as the sorbents of μ-SPE. Among these materials, MOFs materials have shown an exponential growth of interest owe to their microporosity, remarkably low density, extremely large surface area, easily designed or modified to have different pore sizes. However, only MIL-101 [14,15] and ZIF-8 [17,26] have been used as sorbents of μ-SPE for aqueous matrices. One of the main reasons is due to the fact that water molecule could easily penetrate the pores of MOFs and perennially disrupt their framework [18,19]. UiO-66(Zr) (UiO for University of Oslo), first synthesis by Cavka et al. [20], is based on a Zr6O4(OH)4 octahedron, forming lattices by 12-fold connection through the terephthalate linkers, resulting in a cubic close-packed structure [20]. The high degree of topological connectivity together with the strong coordination bonds between zirconium and oxygen renders UiO-66(Zr) to be greatly hydro-stable, even under acidic or some alkaline conditions [21] and performs a high hydrothermal stability up to 450 °C. This provides a theoretical basis of applying UiO-66(Zr) in μ-SPE. UiO-66(Zr) has been used for solid-phase micro-extraction of phenols in water samples [22], magnetic solid-phase extraction of domoic ACET from shellfish samples [23], and adsorptive removal of acid [24] and dyes [25] from water, but no reports of UiO-66 used for membrane protected μ-SPE. Natural and synthetic steroid hormones are recognized for their potential to mimic or interfere with normal hormonal functions (development, growth and reproduction) even at ultratrace levels (ng/L) [26]. They are used extensively in clinical and animal husbandry for the prevention and treatment of diseases. Since they cannot be completely metabolized in the body, such substances are excreted in the urine and eventually enter aquatic environments. Steroid hormones are potential risk for wildlife and humans through the consumption of contaminated food or water [27]. Based on structural differences and affinities, steroid hormones can be divided into five subclasses: estrogens, androgens, progestogens, mineral corticoids and glucocorticoids. With lots of work focusing on estrogens, less attention has put on progestogens and androgens. However, these hormonal systems still play an important role on the maintenance of sexual development, growth, and homeostasis, thus there is still a need for sensitive methods to detect these less studied endpoints in environmental water [28].
    Results and discussion
    Acknowledgements The work was financially supported by the Natural Science Foundation of Liaoning Province of China (Grant No. 201602693).
    Introduction Hormone therapy (HT) is the treatment of choice for the management of bothersome menopausal symptoms and of urogenital atrophy [1]. Since the majority of menopausal complaints are attributed to estrogen deficiency, HT consisted originally of estrogen monotherapy. The increase, however, of endometrial hyperplasia and cancer has mandated the addition of a progestogen to the HT regimen for endometrial protection [2]. Beyond its effect on quality of life, HT increases bone mineral density, decreases the risk of both vertebral and hip fractures as well as the risk of colon cancer in postmenopausal women [3]. HT, furthermore, has a beneficial effect on the postmenopausal cardiometabolic risk by improving the lipid profile [4], by inhibiting abdominal fat accumulation [5] and by improving insulin sensitivity [6]. If administered early after menopause, HT may reduce the risk of ischemic heart disease [7].