DSpace Collection:http://hdl.handle.net/10261/3222024-03-28T17:21:27Z2024-03-28T17:21:27ZSimplex optimization of the analysis of polychlorinated biphenyls: Application to the resolution of a complex mixture of congeners of interest on a single gas chromatographic columnJiménez, BegoñaTabera, JavierHernández, Luis M.González Carlos, María Joséhttp://hdl.handle.net/10261/3332542023-08-17T01:18:52Z2023-08-16T07:12:38ZTítulo: Simplex optimization of the analysis of polychlorinated biphenyls: Application to the resolution of a complex mixture of congeners of interest on a single gas chromatographic column
Autor: Jiménez, Begoña; Tabera, Javier; Hernández, Luis M.; González Carlos, María José
Resumen: The modified sequential simplex method was applied to optimize the oven temperature programming of a single-column gas chromatography procedure developed to determine polychlorinated biphenyl congeners in a mixture of technical Aroclors. Both the overall resolution of fourteen congeners of interest and the time of analysis were taken into account in the optimization. Successful seperations of some clusters usually unresolved with a single column have been obtained.2023-08-16T07:12:38ZTriglyceride composition of ewe, cow, and goat milk fatRuiz-Sala, P.Hierro, M. T. G.Martínez-Castro, IsabelSanta-María, Guillermohttp://hdl.handle.net/10261/3329022023-08-10T01:45:17Z2023-08-09T10:00:21ZTítulo: Triglyceride composition of ewe, cow, and goat milk fat
Autor: Ruiz-Sala, P.; Hierro, M. T. G.; Martínez-Castro, Isabel; Santa-María, Guillermo
Resumen: The separation and identification of the components in milk fat, which are mainly triglycerides, is a challenge due to its complex composition. A reverse-phase high-performance liquid chromatography (HPLC) method with gradient elution and light-scattering detection is described in this paper for the triglyceride analysis in ewes’ milk fat. Triglyceride identification was carried out by combining HPLC, gas-liquid chromatography (GLC), and the calculated equivalent carbon numbers of several triglyceride standards. Quantitation of partially resolved peaks in the HPLC chromatogram was accomplished by applying a peak deconvolution program. Forty-four fatty acids were identified by GLC analysis, but only 19 were used for the following prediction of triglyceride molecular species; 181 triglycerides were identified, some of which were grouped at the same peak and needed application of the deconvolution program. Consequently, coefficients of variation were close to or lower than 5%. Moreover, the triglyceride composition of ewe, cow, and goat milk fat were compared by using these methods. These results show that ewe milk fat is richer in short- and medium-chain triglycerides, and cow milk fat is richer in long-chain and unsaturated triglycerides.2023-08-09T10:00:21ZThermal degradation of different crystalline forms of lactosePáez, M. I.Martínez-Castro, IsabelOlano, Agustínhttp://hdl.handle.net/10261/3328982023-08-10T01:45:14Z2023-08-09T09:55:25ZTítulo: Thermal degradation of different crystalline forms of lactose
Autor: Páez, M. I.; Martínez-Castro, Isabel; Olano, Agustín
Resumen: The thermal degradation of α-lactose hydrate, stable anhydrous α-lactose and β-lactose has been studied. The presence of water vapour decreased the thermal stability of all the crystalline forms studied. α-Lactose hydrate was found to be the least stable form. Under anhydrous conditions β-lactose was the most stable form and anhydrous α-lactose was the most stable in the presence of water vapour.2023-08-09T09:55:25ZReady detection of small amounts of lactulose in dairy products by thin-layer chromatographyMartínez-Castro, IsabelOlano, Agustínhttp://hdl.handle.net/10261/3328952023-08-10T01:45:13Z2023-08-09T09:44:48ZTítulo: Ready detection of small amounts of lactulose in dairy products by thin-layer chromatography
Autor: Martínez-Castro, Isabel; Olano, Agustín
Resumen: Ready detection of lactulose in milk and in mixtures with other sugars is achieved by diluting the sample ten times with acetone and successive thin-layer chromatographic separation on silica gel-boric acid, developed with acetonitrile: water 50∶20. The method allows detection of up to 0.02% lactulose on total carbohydrates and permits a semi-quantitative estimation of lactulose in milk.2023-08-09T09:44:48Z