SummaryThe retention behavior in a C18 column of fourteen steroidal hormones (clostebol acetate, dehydrotestosterone, dydrogesterone, medroxyprogesterone, medroxyprogesterone acetate, methandienone, methyltestosterone, nandrolone, nandrolone decanoate, progesterone, testosterone, testosterone enanthate, testosterone propionate and, stanozolol) with pure micellar mobile phases prepared from sodium dodecyl sulfate (SDS), and hybrid mobile phases comprising SDSacetonitrile and SDS-pentanol, was correlated with their octanol-water partition coefficients. Similar correlations were found with retention data obtained by other authors in gas chromatography, conventional reversedphase liquid chromatography, and micellar electrokinetic chromatography. The retention of the steroids depended on the nature of the R17 substituent in the steroid tetracyclic system. Steroids of low, intermediate, and high retention had hydroxyl, acetyl, and ester groups, respectively. The retention of nandrolone was, however, abnormally high in the presence of micelles, because of the absence of a methyl group at R10. Retention of the compounds in the micellar mobile phases was also evaluated in terms of their solute-micelle and solute-stationary phase association constants.

This review describes the recent advances from the past five years concerning the development and applications of molecularly imprinted membranes (MIMs) in the field of sample treatment and separation processes. After a short introduction, where the importance of these materials is highlighted, a description of key aspects of membrane separation followed by the strategies of preparation of these materials is described. The review continues with several analytical applications of these MIMs for sample preparation as well as for separation purposes covering pharmaceutical, food, and environmental areas. Finally, a discussion focused on possible future directions of these materials in extraction and separation field is also given.

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In this study, porous polymer monoliths were in situ synthesized in fluoropolymers tubing to prepare microbore HPLC columns. To ensure the formation of robust homogeneous polymer monoliths in these housing supports, the inner surface of fluoropolymer tubing was modified in a two-step photografting process. Raman spectroscopy and scanning electron microscopy (SEM) confirmed the successful modification of the inner poly(ethylene-co-tetrafluoroethylene) (ETFE) wall and the subsequent attachment of a monolith onto the wall. Poly(glycidyl methacrylate-co-divinylbenzene), poly(butyl methacrylate-co-ethyleneglycol dimethacrylate) and poly(styrene-co-divinylbenzene) monoliths were in situ synthesized by thermal polymerization within the confines of surface vinylized ETFE tubes. The resulting monoliths exhibited good permeability and mechanical stability (pressure resistance up to 9 MPa). The chromatographic performance of these different monolithic columns was evaluated via the separation of alkyl benzenes and proteins in a conventional HPLC system.

This paper reports an economic, simple and rapid FI-CL method for the determination of MCPA. This method requires simple instrumentation and it is fast enough to be used in routine analyses. Chemiluminescence signal is generated by reaction between photodegraded MCPA and ferricyanide solution in alkaline medium. All physical and chemical parameters in the flow injection chemiluminescence system were optimized in the experimental setting. To eliminate the interferences a solid phase extraction stage with SDB-1 cartridges and ethanol elution is applied. The signal-MCPA concentration relation is linear in concentration intervals between 0.0015 μg·mL -1 and 0.6 μg·mL -1 . The calibration lines are statistically similar in different working conditions: standards with ethanol without extraction and standards with ethanol and extraction, allowing standards to be excluded from the extraction step, which simplifies the process. The detection limit (DL) is 0.5 ng·mL -1 , which is the same order as the maximum limit established in legislation regarding pesticide limits in water destined for human consumption. A DL of 0.13 ng·mL -1 can be reached if a sample of 100 mL is preconcentrated. The interday variance coefficient is 3% and the sample throughput is 90 hour -1 . The water analysis method is efficient with relative error percentages lower than 5% with respect to the added concentration.