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J M Bosque-Sendra

Publications and source records attributed to J M Bosque-Sendra.

6 recordsLinked to original sources
PubMed2003

Applying non-parametric statistical methods to the classical measurements of inclusion complex binding constants.

A study on using non-parametric statistical methods was carried out to calculate the binding constant of an inclusion complex and to estimate its associated uncertainty. First, a correct evaluation of the stoichiometry was carried out in order to ensure an accurate determination of the binding constant. For this purpose, the modified Benesi-Hildelbrand method had been previously applied. Then, four statistical methods (three non-parametric methods: two bootstrap approaches, the jackknife method and a parametric one: Fieller's theorem) were employed in order to compute the binding constant. The results obtained from applying these methods and the combination of the methods: jackknife after bootstrap and bootstrap after jackknife were compared. The best results in terms of accuracy were obtained from the application of a bootstrap method: the resampling residuals approach. These procedures were applied to the inclusion complex 2-hydroxil-propyl-beta-cyclodextrin-2,4-dichloro-phenoxyacetic, which shows photochemically-induced fluorescence.

Binding Sites↗
PubMed2003

Use of factorial design and Doehlert matrix for multivariate optimisation of an on-line preconcentration system for lead determination by flame atomic absorption spectrometry.

A system for on-line preconcentration and determination of lead by flame atomic absorption spectrometry (FAAS) was proposed. It was based on the sorption of lead(II) ions on a minicolumn of polyurethane foam loaded with 2-(2-thiazolylazo)-5-dimethylaminophenol (TAM). The optimisation step was carried out using two-level full factorial and Doehlert designs for the determination of the optimum conditions for lead preconcentration. The proposed procedure allowed the determination of lead with a detection limit of 2.2 microg L(-1), and a precision, calculated as relative standard deviation (RSD), of 2.4 and 6.8 for a lead concentration of 50.0 and 10.0 microg L(-1), respectively. A preconcentration factor of 45 and a sampling frequency of 27 samples per hour were obtained. The recovery achieved for lead determination in the presence of several cations demonstrated that this procedure has enough selectivity for analysis of environmental samples. The validation was carried out by analysis of certified reference material. This procedure was applied to lead determination in natural food.

Cations↗
PubMed2001

Optimizing analytical methods using sequential response surface methodology. Application to the pararosaniline determination of formaldehyde.

Sequential response surface methodology is a general procedure to re-optimize common analytical methods on the basis of the application of the response surface methodology and of a new approach to the steepest ascent method. This procedure, which is easy to apply, consists of estimating an analytical function relating the response with the experimental parameters by means of a second-degree polynomial. Thus, a 2nd order design covering the total experimental domain is used and when a maximum is obtained, the characteristics of the response surface are confirmed using a new design, which is obtained contracting the first one. In the proposed methodology, Box-Behnken designs are used because they offer advantages in comparison with second order designs more frequently used in the steepest ascent method (central composite designs), i.e. fewer experiments are needed, they are more efficient, they can be moved through the experimental domain and they can even be easily contracted or expanded.

Journal Article↗
PubMed1996

Determination of proteins in the presence of imidazole buffers.

Imidazole buffers were found to interfere with the determination of soluble proteins using Lowry's classical method. The influence of the constituent elements of the buffer on the calibration line was studied statistically. By combining the data corresponding to different experimental sequences, interserial calibration curves for different concentrations of imidazole buffer (10-30 mM) were obtained. The absorbance-buffer volume dependence curves produced a good fit to second-order polynomials. The accuracy of protein determination in a medium with imidazole buffer, using appropriate calibration curves, were tested by comparison with the technique of multiple standard addition and by means of recovery studies. These experiments were performed on chick brain homogenate samples. Other important aspects of validation, such as sensitivity and accuracy, were also studied.

Animals↗