Jose Ramon Torres-Lapasio
University of Valencia
MicelleAnalytical chemistrySelectivityWork (thermodynamics)Column (database)DeconvolutionHigh-performance liquid chromatographyChemistryAcetonitrileSilanolSolventPhase compositionGradient elutionChromatographyPhase (matter)Reversed-phase chromatographyComputationMicellar liquid chromatographyPulmonary surfactantElutionResolution (mass spectrometry)
110Publications
30H-index
2,436Citations
Publications 100
Newest
#1A. Gisbert-Alonso (University of Valencia)H-Index: 1
#2J.A. Navarro-Huerta (University of Valencia)H-Index: 6
Last. M.C. García-Alvarez-Coque (University of Valencia)H-Index: 31
view all 4 authors...
Abstract The resolution of samples containing unknown compounds of different nature, or without standards available, as is the case of chromatographic fingerprints, is still a challenge. Possibly, the most problematic aspect that prevents systematic method development is finding models that describe without bias the retention behaviour of the compounds in the samples. In this work, the use of global models (able to describe the whole sample) is proposed as an alternative to the use of individual...
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#1J.A. Navarro-Huerta (University of Valencia)H-Index: 6
#2A. Gisbert-Alonso (University of Valencia)H-Index: 1
Last. M.C. García-Alvarez-Coque (University of Valencia)H-Index: 31
view all 4 authors...
Abstract The basis of interpretive optimisation in liquid chromatography is the prediction of resolution, from appropriate solute retention models. The reliability of the process depends critically on the quality of the experimental design. This work develops, validates and applies a general methodology aimed to evaluate the quality of any training experimental design, which will be applied in Part II to design optimisation. The methodology is based on the systematic evaluation of the uncertaint...
1 CitationsSource
#1María Vergara-Barberán (University of Valencia)H-Index: 9
#2J.A. Navarro-Huerta (University of Valencia)H-Index: 6
Last. M.C. García-Alvarez-Coque (University of Valencia)H-Index: 31
view all 5 authors...
Abstract The development of a new comprehensive two-dimensional liquid chromatographic method is described, to obtain the profiles of polyphenolic compounds present in olive (Olea europaea L.) leaves and pulps from different genetic origin. Optimisation of the stationary phase nature, particle size, column length and internal diameter, as well as other separation conditions, was performed. Along the study, three stationary phases (C18, PFP and phenyl) in the first dimension (1D), and five (C18, ...
1 CitationsSource
#1J.A. Navarro-Huerta (University of Valencia)H-Index: 6
#2A.G. Vargas-García (University of Valencia)
Last. M.C. García-Alvarez-Coque (University of Valencia)H-Index: 31
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Abstract Micellar liquid chromatography (MLC) is a reversed-phase mode with mobile phases containing an organic solvent and a micellised surfactant. Most procedures developed in MLC are implemented in the isocratic mode, since the general elution problem in chromatography is less troublesome. However, gradient elution may be still useful in MLC to analyse mixtures of compounds within a wide range of polarities, in shorter times. MLC using gradients is attractive to determine by direct injection ...
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#1T. Alvarez-Segura (University of Valencia)H-Index: 5
#2Sergio López-Ureña (University of Valencia)H-Index: 5
Last. M.C. García-Alvarez-Coque (University of Valencia)H-Index: 31
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Abstract Multi-linear gradients are a convenient solution to get separation of complex samples by modulating carefully the gradient slope, in order to accomplish the local selectivity needs for each particular solute cluster. These gradients can be designed by trial-and-error according to the chromatographer experience, but this strategy becomes quickly inappropriate for complex separations. More evolved solutions imply the sequential construction of multi-segmented gradients. However, this stra...
2 CitationsSource
#1J.A. Navarro-Huerta (University of Valencia)H-Index: 6
#2Enrique Javier Carrasco-Correa (University of Valencia)H-Index: 12
Last. M.C. García-Alvarez-Coque (University of Valencia)H-Index: 31
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Abstract The development of methacrylate-based monolithic columns was studied for the separation of pharmaceutical hydrophilic compounds in nano-liquid chromatography. The selected polymerisation mixture consisted of 7.5% hexyl methacrylate, 4.5% methacrylic acid and 18.0% ethylene dimethacrylate (w/w), in a binary porogenic solvent (35:35 w/w 1-propanol/1,4-butanediol). The polymer synthesised with this mixture has a good permeability, not excessive back-pressure, and reasonable retention times...
4 CitationsSource
#1Sergio López-Ureña (University of Valencia)H-Index: 5
#2Jose Ramon Torres-Lapasio (University of Valencia)H-Index: 30
Last. M.C. García-Alvarez-Coque (University of Valencia)H-Index: 31
view all 3 authors...
Abstract Gradient elution may provide adequate separations within acceptably short times in a single run, by gradually increasing the elution speed. Similarly to isocratic elution, chromatograms can be predicted under any experimental condition, through strategies based on retention models. The most usual approach implies solving an integral equation (i.e., the fundamental equation of gradient elution), which has an analytical solution only for certain combinations of retention model and gradien...
5 CitationsSource
#1J.A. Navarro-Huerta (University of Valencia)H-Index: 6
#2A. Gisbert-Alonso (University of Valencia)H-Index: 1
Last. M.C. García-Alvarez-Coque (University of Valencia)H-Index: 31
view all 4 authors...
Abstract The advantages and disadvantages of the use of isocratic experimental designs including transient increments of organic solvent (i.e., pulses) in the mobile phase(s) of lowest elution strength are explored with modelling purposes. For retained solutes, this type of mixed design offers similar or better predictive capability than gradient designs, shorter measurement time than pure isocratic designs, and retention model parameters that agree with those derived from pure isocratic experim...
5 CitationsSource
#1J.A. Navarro-Huerta (University of Valencia)H-Index: 6
#2Jose Ramon Torres-Lapasio (University of Valencia)H-Index: 30
Last. M.C. García-Alvarez-Coque (University of Valencia)H-Index: 31
view all 3 authors...
Abstract Peak capacity (PC) is a key concept in chromatographic analysis, nowadays of great importance for characterising complex separations as a criterion to find the most promising conditions. A theoretical expression for PC estimation can be easily deduced in isocratic elution, provided that the column plate count is assumed constant for all analytes. In gradient elution, the complex dependence of peak width with the gradient program implies that an integral equation has to be solved, which ...
4 CitationsSource
#1T. Alvarez-Segura (University of Valencia)H-Index: 5
#2Jose Ramon Torres-Lapasio (University of Valencia)H-Index: 30
Last. María Celia García-Alvarez-Coque (University of Valencia)H-Index: 21
view all 3 authors...
The most efficient optimization methodologies in liquid chromatography are based on the modeling and prediction of the chromatographic behavior for each compound in the sample. However, when the column suffers some ageing after the modeling process, predictions may differ significantly from the actual separation. Repeating the modeling is especially troublesome when several columns are involved, as is the case of coupled columns. We propose a shortcut to correct the time and peak profiles in the...
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