Publicaciones 2011-2020

@article{RN231,
title = {Determination of Etonogestrel and Ethinyl Estradiol from an Intrauterine Contraceptive Ring by Extraction and Derivative Spectrophotometry},
author = { M.I. Toral and F. Nacaratte and F. Nova},
url = {/brokenurl#<Go to ISI>://WOS:000348519800011},
doi = {10.1080/00032719.2014.968930},
issn = {0003-2719},
year = {2015},
date = {2015-01-01},
journal = {Analytical Letters},
volume = {48},
number = {6},
pages = {1009-1020},
abstract = {A new method for the determination and extraction of ethinyl estradiol and etonogestrel was developed for a pharmaceutical product consisting of a solid copolymer intrauterine ring for subsequent simultaneous quantification by ultraviolet-visible derivative spectrophotometry. The spectral variables were optimized for first derivative spectrophotometry with a smoothing factor of 4000 and an amplification factor of 10,000. A wavelength of 291.5nm was selected for the determination of ethinyl estradiol by a graphical method, while for etonogestrel, zero-crossing was used at 249.5nm. The limits of detection and quantification for ethinyl estradiol were 9.5x10(-7) and 9.0x10(-6)mol/L and 1.1x10(-6) and 3.2x10(-6)mol/L for etonogestrel, respectively. For the extraction method, the variables affecting the analytical signal were the extraction solvent, temperature, and extraction time; optimized conditions were 180min at 76 +/- 2 degrees C in acetonitrile. The method was applied successfully for the first time to analyze intrauterine contraceptive rings. The sample contained 11.7mg etonogestrel and 2.7mg ethinyl estradiol; the recoveries were 93.6 +/- 1.1% etonogestrel and 97.9 +/- 1.5% ethinyl estradiol relative to the nominal concentration. The importance of this method involves its implementation in pharmaceutical laboratories.},
keywords = {contraceptive cyproterone-acetate, desogestrel, estradiol, ethinyl etonogestrel, formulation, intrauterine mass-spectrometry, pharmaceutical plasma properties, release ring, spectrophotometry},
pubstate = {published},
tppubtype = {article}
}

@article{RN109,
title = {Co-Determination of Two Antiparasitics Drugs by Derivative Spectrophotometry and Its Photodegradation Studies},
author = { C. Soto and R. Otipka and D. Contreras and J. Yanez and M.I. Toral},
url = {/brokenurl#<Go to ISI>://WOS:000331238200006},
doi = {10.4067/S0717-97072013000300006},
issn = {0717-9707},
year = {2013},
date = {2013-01-01},
journal = {Journal of the Chilean Chemical Society},
volume = {58},
number = {3},
pages = {1824-1829},
abstract = {This work proposes a method for the co-determination of praziquantel and fenbendazole in veterinary pharmaceutical formulations (VPF) by second-derivative spectrophotometry at 226.4 nm (Zero-crossing method) and 324.6 nm (Graphic method), respectively. The excipients commonly used in VPF do not interfere. To obtain the optimal determination conditions, studies of solvent and light effects, were performed. The results of the light effects show that the expose of both drugs to indirect light and darkness does not produce any chemical change, since their zero-order spectra remained unchanged during the experiment. However, the exposition to the direct light only affects the fenbendazole. The zero order spectrum of FBZ in EtOH-HCl, present two broad bands (200 to 240 nm and 260 to 330 nm), these signals disappear and appear others totally different, at 230 nm and other with two peaks (285 and 295 nm). The FT-IR spectrum shows characteristics signals of the FBZ structure as the amide-NH group (3336.3 cm(-1)), this signal disappear indicating the bond break of the amide group caused by the exposition to sunlight for a time. These spectral changes evidenced a structural transformation as a result of photochemical decomposition in acid medium.},
keywords = {derivative determination, fenbendazole, formulations formulations, human liquid-chromatography, performance photochemical plasma, praziquantel, spectrophotometry, veterinary voltammetric},
pubstate = {published},
tppubtype = {article}
}