Examinando por Autor "Marina, María Luisa"

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One-pot synthesized functionalized mesoporous silica as a reversed-phase sorbent for solid-phase extraction of endocrine disrupting compounds in milks
(Elsevier, 2015-09) Gañán, Judith; Morante-Zarcero, Sonia; Pérez-Quintanilla, Damián; Marina, María Luisa; Sierra, Isabel
A new procedure for the determination of twelve naturally occurring hormones and some related synthetic chemicals in milk, commonly used as growth promoters in cattle, is reported. The method is based on liquid-liquid extraction followed by solid-phase extraction (SPE) using a new one-pot synthesized ordered mesoporous silica (of the SBA-15 type) functionalized with octadecyl groups (denoted as SBA-15-C18-CO) as reversed-phase sorbent. The analytes were eluted with methanol and then submitted to HPLC with diode array detection. Under optimal conditions, the method quantification limit for the analytes ranged from 0.023 ¿g/mL to 1.36 ¿g/mL. The sorbent affored the extraction of estrone, 17ß-estradiol, estriol, progesterone, hexestrol, diethylstilbestrol, 4- androstene-3,17-dione, ethinylestradiol, 17¿-methyltestosterone, nandrolone, prednisolone and testosterone with mean recoveries ranging from 72 to 105% (except for diethylstilbestrol) with RSD < 11%. These results were comparable and, in some cases, even better than those obtained with other extraction methods, therefore SBA-15- C18-CO mesoporous silica possess a high potential as a reversed-phase sorbent for SPE of the twelve mentioned endocrine disrupting compounds in milk samples.
Ordered mesoporous silica functionalized with ß-cyclodextrin derivative for optical isomer separation of flavanones and flavanone glycosides by nano-liquid chromatography and capillary electrochromatography
(Elsevier, 2017) Silva, Mariana; Pérez-Quintanilla, Damián; Morante-Zarcero, Sonia; Sierra, Isabel; Marina, María Luisa; Aturki, Zeineb; Fanali, Salvatore
In this paper a novel chiral stationary phase (CSP) was prepared by the immobilization of a ß-CD derivative (3,5-dimethylphenylcarbamoylated ß-CD) onto the surface of amino-functionalized spherical ordered mesoporous silica (denoted as SM) via a urea linkage using the Staudinger reaction. The CSP was packed into fused silica capillaries 100 ¿m I.D. and evaluated by means of nano-liquid chromatography (nano-LC) and capillary electrochromatography (CEC) using model compounds for the enantioseparation and the diastomeric separation. The compounds flavanone, 2¿-hydroxyflavanone, 4¿-hydroxyflavanone, 6-hydroxyflavanone, 4¿-methoxyflavanone, 7-methoxyflavanone, hesperetin, hesperidin, naringenin, and naringin were studied using reversed and polar organic elution modes. Baseline optical isomers resolution and good results in terms of peak efficiency and short analysis time of all studied flavonoids and flavanones glycosides was achieved in reversed phase mode, using a mixture of MeOH/H2O, 10 mM ammonium acetate pH 4.5 at different ratios as mobile phase. For the polar organic mode using 100 % of MeOH as mobile phase, the CSP showed better performances, the baseline chiral separation of several studied compounds occurred in an analysis time of less than 10 min. Also good results were achieved by CEC employing two different mobile phases. The use of MeOH/H2O, 5 mM ammonium acetate buffer pH 6 (90/10, v/v) was very effective for the chiral resolution of flavanone and its methoxy and hydroxy derivatives.