María Cruz Ortiz

Universidad de Burgos | UBU · Department of Chemistry

Analytical Quality by Design (AQbD) is the adaptation of Quality by Design (QbD) when it is applied to the development of an analytical method. The main idea is to develop the analytical method in such a way that the desired quality of the Critical Quality Attributes (CQAs), stated via the analytical target profile (ATP), is maintained while allowi...

In this paper, an integrated design of a supermarket refrigeration system has been used to obtain a process with better operability. It is formulated as a multi-objective optimization problem where control performance is evaluated by six indices and the design variables are the number and discrete power of each compressor to be installed. The funct...

A new multi-factor multi-objective strategy to approach the joint assessment of the effect of six experimental factors in the determination by head space-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) of eight different additives commonly used in the plastic packaging manufacturing is proposed in this work. Five HS...

The paper presents a new methodology within the framework of the so-called compliant class-models, PLS2-CM, designed with the purpose of improving the performance of class-modelling in a setting with more than two classes. The improvement in the class-models is achieved through the use of multi-response PLS models with the classes encoded via Error...

The purpose of this work is to develop a tool to search for a gradient profile with ternary or binary mixtures in liquid chromatography, that can provide well-resolved chromatograms in the shortest time for multianalyte analysis. This approach is based exclusively on experimental data and does not require a retention time model of the compounds to...

The aim of this work is focused on the melamine migration from food contact materials (FCMs), considering data obtained from univariate analysis versus that obtained from multivariate approach in liquid chromatography coupled to diode array detector. Plastic food contact materials are made from monomers and additives. Moreover, non-intentionally ad...

The paper presents a new proposal for a single overall measure, the diagonal modified confusion entropy (DMCEN), to assess the performance of class-models jointly computed for several classes, a versatile index regarding sensitivity and specificity, and that supports class weighting. The characteristics of the proposed figure of merit are illustrat...

A chromatographic method with the Analytical Quality by Design (AQbD) methodology is developed for the simultaneous determination by HPLC-FLD of ten PAHs (naphthalene, phenanthrene, anthracene, fluoranthene, pyrene, chrysene, benzo[a]anthracene, perylene, benzo[b]fluoranthene, and benzo[a]pyrene), widely spread in the environment. The construction...

In the context of binary class-modelling techniques, the paper presents the computation in the input space of linear boundaries of a class-model constructed with given values of sensitivity and specificity. This is done by inversion of a decision threshold, set with these values of sensitivity and specificity, in the probabilistic class-models comp...

This paper reports on the difficulties encountered when developing an analytical method for ultra-trace determination, in a complex matrix, of plastic additive residues which are ubiquitous in the laboratory. The simultaneous qualitative and quantitative determination of an antioxidant (2,6-di-tert-butyl-4-methyl-phenol, BHT), an UV stabilizer (ben...

Bisphenol A (BPA) is considered an endocrine disrupting chemical as it affects the human hormonal system and is widely used in polycarbonate (PC) manufacture. As the population is continually exposed to BPA, European regulations have limited its industrial use in cosmetics, thermal paper, toys and food contact materials. Because of these restrictio...

Relative errors are typically used in chemometrics to evaluate the performance of a multivariate predictive model. However, these models are not obtained through the criterion of minimizing relative errors, as would be expected in a model whose response is the concentration of an analyte. There are no studies in chemometrics on the use of a princip...

Inside the framework of Analytical Quality by Design, a model-based approach has been developed and used to identify operating conditions (control method parameters) related to the composition and flow rate of the mobile phase for a liquid chromatographic determination with preset quality characteristics. The approach starts by defining these desir...

The paper shows a procedure for selecting the control method parameters (factors) to obtain a preset ‘analytical target profile’ when a liquid chromatographic technique is going to be carried out for the simultaneous determination of five bisphenols (bisphenol-A, bisphenol-S, bisphenol-F, bisphenol-Z and bisphenol-AF), some of them regulated by the...

The paper contains a discussion about the null spaces associated to linear prediction models for the particular case of Partial Least Squares regression models. The discussion separately considers the two existing null spaces: the one in the input space related to the projection onto the latent space and the null space, coming from the projection s...

The need of performing “in situ” analytical determinations together with the availability of high-power deep UV-LEDs have led to the use of fluorescence spectroscopy. However, it is necessary to register excitation-emission matrices (EEM) to obtain three-way data which can be decomposed using parallel factor analysis for enabling the unequivocal id...

The growing demand for controls of foodstuffs, personal care products, medicines and the environment is unquestionable, as well as a better understanding of the toxicity of chemical products. This causes a growing need to propose methods of analysis for the unequivocal identification and quantification of analytes in complex samples. Several offici...

The efficiency of the analytical methods based on vibrational spectroscopy has been widely verified in a high number of publications. In addition, it has been recognized that the pretreatment of the original signals is absolutely necessary to obtain enough quality in the subsequent classification and/or regression models. In fact, an inappropriate...

In general, the calibration of an instrument involves a set of calibration standards with known concentration to measure the response of the instrument for each standard, and to fit a model to establish the relationship between the instrumental response and the concentration of the analyte, regression model that is used to transform the measurement...

It is well known that several polycyclic aromatic hydrocarbons (PAHs), products of incomplete pyrolysis of organic material, have proved to be extremely toxic to humans. Food can be contaminated by these compounds in many different ways and diet represents nowadays the major source of exposure to PAHs for non-smokers population. In the present stud...

The simultaneous determination of 2,6-di-tert-butyl-4-methyl-phenol (BHT), benzophenone (BP), benzophenone-3 (BP3) and diisobutyl phthalate (DiBP) in seven sunscreen creams was carried out by gas chromatography/mass spectrometry (GC/MS) using DiBP-d4 as internal standard. The content of BP3, which is a UV filter, must not exceed 6% (w/w) in cosmeti...

In this work, the transfer of the excitation-emission matrices between a portable fluorimeter based on LEDs and a master fluorimeter based on a xenon source was carried out. Enrofloxacin was the analyte of interest and it was measured alone or in binary mixtures with flumequine (partially overlapped signals) or with ciprofloxacin (fully overlapped...

European legislation has established a specific migration limit (SML) of 15 mg kg ⁻¹ for formaldehyde and 2.5 mg kg ⁻¹ for melamine. Formaldehyde resins are used in the manufacture of melamine kitchenware. Formaldehyde is listed in group 1 of the IARC list of carcinogenic compounds. To determine the quantity of formaldehyde and melamine as potentia...

The maintenance of the cold chain is essential to ensure foodstuff conformity and safety. However, gaps in the cold chain may be expected so designing analytical methods capable to detect cold chain breaks is a worthwhile issue. In this paper, the possibility of using the amount of nine biogenic amines (BAs)determined in Thunnus albacares by HPLC-F...

A procedure based on a D-optimal design coupled with PARAFAC was proposed to optimise signals from molecular fluorescence spectroscopy to obtain the best experimental conditions for the achievement of the best fluorescence signal of green tea samples. Excitation-emission signals (EEMs) were used to analyse the liquid samples (tea infusions), wherea...

The determination of cochineal (E-120) in strawberry jam was carried out in the presence of carmoisine (E-122) using the four-way PARAFAC decomposition and excitation-emission fluorescence matrices. In the measured conditions, there was no fluorescence signal for carmoisine due to a strong quenching effect and this colorant also led to a decrease o...

The simultaneous determination of two food colorants (cochineal (E-120) and erythrosine (E-127)) was achieved by means of excitation-emission fluorescence matrices and three-way PARAFAC decomposition together with the use of a calibration set that contained binary mixtures of both analytes. In the measured conditions, the amount of cochineal presen...

The migration of benzophenone (BP), an antioxidant (2,6-di-tert-butyl-4-methyl-phenol (BHT)) and three plasticizers (diisobutyl phthalate (DiBP), bis(2-ethylhexyl) adipate (DEHA) and diisononyl phthalate (DiNP)) from different food contact materials into Tenax as food simulant was studied. The packaging materials analysed were: polyethylene (PE) an...

In the context of the paradigms founding the Quality by Design and Process Analytical Technology initiatives, the work herein presents a computational approach to support the decision-making process, in particular, about the feasibility of a product defined for some a priori given quality characteristics. The approach is based on the computation of...

In this study, an alternative analytical approach for analyzing and characterizing green tea (GT) samples is proposed, based on the combination of excitation-emission matrix (EEM) fluorescence spectroscopy and multivariate chemometric techniques. The three-dimensional spectra of 63 GT samples were recorded using a Perkin-Elmer LS55 luminescence spe...

Green tea (GT), as a world's most consumed beverage, recently has extensively being studied to evaluate its antioxidant activity and its potential for reducing lifestyle-related diseases. The price of the tea varies greatly according to its geographical origin. So, the recognition of the origin of green tea is crucial to protect the interests of co...

The impact that the presence of nanoparticles in food can have on the migration from food contact materials (FCMs) of substances, which occurrence in foodstuffs is regulated, is posed in this paper through a case-study. Migration of bisphenol A (BPA) from polycarbonate glasses into aqueous food simulant B (3% acetic acid, w/v) and simulant D1 (50%...

Background: Despite long-lasting HIV replication control, a significant proportion of elite controller (EC) patients may experience CD4 T-cell loss. Discovering perturbations in immunological parameters could help our understanding of the mechanisms that may be operating in those patients experiencing loss of immunological control. Methods: A ca...

This paper presents the simultaneous determination of a UV stabilizer (benzophenone (BP)) together with four plasticizers (butylated hydroxytoluene (BHT), diisobutyl phthalate (DiBP), bis(2-ethylhexyl) adipate (DEHA) and diisononyl phthalate (DiNP)) in Tenax by gas chromatography/mass spectrometry and PARAFAC, using DiBP-d4 as internal standard. Re...

Legal limits for phenol and bisphenol-A (BPA) in toys are 15 and 0.1 mg L⁻¹ respectively. The latest studies show that in Europe the content of BPA, which reaches our bodies through different contact routes, in no cases exceed legal limits. But it is true that the effects caused by continued intake of this analyte for a long time and other possible...

A new multiway/multivariate approach is proposed to study and model the spoilage of swordfish with time and temperature of storage through the profiles of putrescine, spermidine, histamine, tyramine, tryptamine, cadaverine, spermine, and 2-phenylethylamine. The evolution of these biogenic amines in food is a complex process that cannot be character...

Green tea (GT), as a world's most consumed beverage, recently has extensively being studied to evaluate its antioxidant activity and its potential for reducing lifestyle-related diseases. The obtained electrokinetic chromatography data shows that Japanese Commercial GT samples contain a general lower catechins and methylxanthines level than Chinese...

Several analytical procedures depend on multivariate calibration models, such as partial least squares (PLS) models fitted with nearinfrared (NIR) and midinfrared (MIR) spectroscopy signals. Most of these models are related to products that require the control of maximum (or minimum) legally defined limits so that assessing the risks of false nonco...

Bisphenol A (BPA) is one of the most largely produced chemical in the world; it is used to make plastics and epoxy resins. The endocrine disruptor potential of BPA is well known, but recent researches suggest a relationship between chronic exposure to BPA, genotoxic activity and epigenetic modifications. The main source of exposure to BPA includes...

A new strategy to approach multiresponse optimization in conjunction to a D-optimal design for simultaneously optimizing a large number of experimental factors is proposed. The procedure is applied to the determination of biogenic amines (histamine, putrescine, cadaverine, tyramine, tryptamine, 2-phenylethylamine, spermine and spermidine) in swordf...

An algorithmic implementation is presented to deal with several responses in mixtures problems, without theoretical limits on the number of responses or on the factors to be blended. Also, constrained and unconstrained domains are handled, as well as domains with both mixtures and discrete variables. Besides, an alternative way of interpreting the...

Determining plasticizers and other additives migrated from plastic materials becomes a hard task when these substances are already present in the laboratory environment. This work dealt with this drawback in the multiresidue determination of four plasticizers (2,6-di-tert-butyl-4-methyl-phenol (BHT), diisobutyl phthalate (DiBP), bis(2-ethylhexyl) a...

Primary aromatic amines, PAAs, and their derivatives constitute a health risk and control of their migration from food contact materials is the subject of permanent attention by the authorities. 25.1% of notifications made by Rapid Alert System for Food and Feed in the European Union between 2010 and 2015 concerned PAAs, polyamide cooking utensils...

Biogenic amines are formed from precursor amino acids by various microorganisms present in wine, and this may happen at any step of production, ageing or storage. The presence of these compounds is important because high amounts of them can lead to health problems. Also, biogenic amines can be potentially applied as indicators of food spoilage and/...

In this work, the robustness of the sample preparation procedure for the determination of six tranquillizers (xylazine, azaperone, propionylpromazine, chlorpromazine, haloperidol and azaperol) and a beta-blocker (carazolol) in animal muscle by LC/MS–MS was assessed through the experimental design methodology. A 2III7 − 4fractional factorial design...

Numerous research activities generate data that are organized as a three-way tensor, which can be described with PARAFAC. This chapter starts by briefly describing the PARAFAC model and the properties that support its practical utility. Besides, two alternative models are presented, PARAFAC2 and Tucker3, which are useful when the data are inconsist...

Internal standards can be added at different stages of an analytical procedure. When they are added at the beginning of a multiresidue method and their behavior is not exactly the same as that of the analytes, the intended correction for small variations within the analytical process could not be achieved. Because of this, in the present work, the...

This work assesses the reuse of waste expanded polystyrene (EPS) to obtain lightweight cement mortars. The factors and interactions which affect the properties of these mortars were studied by ad-hoc designs based on the d-optimal criterion. This method allow multiple factors to be modified simultaneously, which reduces the number of experiments co...

La toma de decisiones mediante análisis multivariante de datos.

The proper ripening of grapes is the key to obtain a high quality wine. Ripening is a temporal process that is influenced, in addition to uncontrollable climate factors, by the spatial distribution of the vineyard and planted variety. It is a complex process that cannot be characterized by a single parameter; rather it is a modification of the prof...

Three fluorogenic sensory polymer membranes, film shaped (one organic and two hybrids containing complexes of Tb(III) and Sm(III)) based on a dicoumarol motif were designed and prepared for use as sensory matrices to selectively detect nitro explosives (TNT, RDX and PETN) in the environment. Thus, the exposure of these membranes to these explosives...

The simultaneous determination of two carbamate pesticides (carbaryl and carbendazim) and of the degradation product of carbaryl (1-naphthol) in iceberg lettuce was achieved by means of PARAFAC decomposition and excitation-emission fluorescence matrices. A standard addition method for a calibration based on four-way data was applied using different...

An 'ad-hoc' experimental design to handle the robustness study for the simultaneous determination of dichlobenil and its main metabolite (2,6-dichlorobenzamide) in onions by programmed temperature vaporization-gas chromatography-mass spectrometry (PTV-GC-MS) is performed. Eighteen experimental factors were considered; 7 related with the extraction...

The curricula defined by the University of Burgos in the Master of Human Evolution establish generic skills as criticism, analysis, synthesis, problem-solving, independent reading and project work, and other specific skills as handling and processing data [1]. Visualization and data analysis are central in modern physical anthropology for analysis...

This paper presents, on the one hand, the study of the influence of the pH of the medium on the determination of bisphenol F (BPF), bisphenol A (BPA) and their corresponding diglycidyl ethers (BFDGE and BADGE, respectively) by GC-MS after a solid-phase extraction step, using BPA-d16 as internal standard and Parallel Factor Analysis (PARAFAC) decomp...

A non-separative, fast and inexpensive spectrofluorimetric method based on the second order calibration of excitation-emission fluorescence matrices (EEMs) was proposed for the determination of carbaryl, carbendazim and 1-naphthol in dried lime tree flowers. The trilinearity property of three-way data was used to handle the intrinsic fluorescence o...

In this work, a headspace solid-phase microextraction and gas chromatography coupled with mass spectrometry (HS-SPME-GC/MS) method for trace determination of primary aromatic amines was developed. The following analytes were investigated: aniline (A), 4,4′-diaminodiphenylmethane (4,4′-MDA) and 2,4-diaminotoluene (2,4-TDA) using 3-chloro-4-fluoroani...

Near‐infrared spectroscopy has been used in nutritional metabolomics fingerprinting for the assessment of the intake of intervention breakfasts prepared with four different vegetable oils that were previously subjected to a deep frying process of 20 cycles for 5 min at 180°C. The target oils were an extra virgin olive oil and three varieties of ref...

The paper shows some tools (its interpretation and usefulness) to optimize a derivatization reaction and to more easily interpret and visualize the effect that some experimental factors exert on several analytical responses of interest when these responses are in conflict. The entire proposed procedure has been applied in the optimization of equili...

Bisphenol A (BPA), bisphenol F (BPF) and their corresponding diglycidyl ethers (BADGE and BFDGE) are simultaneously determined using a programmed-temperature vaporizer-gas chromatography/mass spectrometry (PTV-GC/MS) system. BPA is used in the production of polycarbonate (PC), whereas BADGE and BFDGE are for manufacturing epoxy resins. Several food...

The determination of triazines in oranges using a GC-MS system coupled to a programmed temperature vaporizer (PTV) inlet in the context of legislation is performed. Both pretreatment (using a Quick Easy Cheap Effective Rugged and Safe (QuEChERS) procedure) and injection steps are optimized using D-optimal experimental designs for reducing the exper...

The ripeness of grapes at the harvest time is one of the most important parameters for obtaining high quality red wines. Traditionally the decision of harvesting is to be taken only after analysing sugar concentration, titratable acidity and pH of the grape juice (technological maturity). However, these parameters only provide information about the...

The problem of blocking experimental designs is addressed, for both factorial type designs and response surface designs (i.e. for discrete and continuous experimental domains). The focus is to arrange block as orthogonally as possible. To measure the uncorrelatedness between the block and the coefficient estimates, we use directly the corresponding...

In this work an analytical procedure based on headspace solid-phase microextraction and gas chromatography coupled with mass spectrometry (HS-SPME–GC/MS) is proposed to determine chlorophenols with prior derivatization step to improve analyte volatility and therefore the decision limit (CCα). After optimization, the analytical procedure was applied...

Experimental designs for a given task should be selected on the base of the problem being solved and of some criteria that measure their quality. There are several such criteria because there are several aspects to be taken into account when making a choice. The most used criteria are probably the so-called alphabetical optimality criteria (for exa...

Near-infrared transmittance (NIT) spectroscopy was used to predict the percentage in weight of the fat, dry matter, protein and fat/dry matter contents in Zamorano cheeses, protected with a Designation of Origin by the European Union. A total of 42 cheeses submitted to official control were analysed by reference methods. Samples were scanned (850-1...

The proposed procedure is described by applying it to develop an analytical method which fulfils the SANCO specifications. Nevertheless, the procedure would be valid for any other legal specification that requires the identification of the analyte by means its m/z values and retention time. To demonstrate the procedure, three herbicides (simazine,...

The present work proposes an analytical procedure to determine sulfathiazole in milk by using molecular fluorescence spectroscopy. For this sulfonamide the European Union in Regulation 37/2010 has established a maximum residue limit in milk of 100 μg kg(-1). The study includes the effect of six factors on the recovery of sulfathiazole. The factors...

In this work, a procedure based on solid-phase microextraction and gas chromatography coupled with mass spectrometry is proposed to determine chlorophenols in water without derivatization. The following chlorophenols are studied: 2,4-dichlorophenol; 2,4,6-trichlorophenol; 2,3,4,6-tetrachlorophenol and pentachlorophenol. Three kinds of SPME fibers,...

Non-intentionally added substances (NIASs) are usually detected by acquiring mass spectra in full scan mode and then identifying the compounds corresponding to the unexpected peaks. High-resolution mass spectrometry detectors are frequently used, but this does not solve the problem that an NIAS can contribute to the abundance at m/z ratios that cor...

An experimental design optimization is reported of an analytical procedure used in the simultaneous determination of seven non-steroidal anti-inflammatory drugs (NSAIDs) in bovine milk by gas chromatography with mass spectrometry detection (GC-MS). This analytical procedure involves a solid-phase microextraction (SPME) step and an aqueous derivatiz...

The paper shows tools to visualize and more easily interpret the effect that some experimental factors may exert on analytical responses of interest when optimization of several responses is needed. It is based on an adaptation of the parallel coordinate plot, a tool for graphical representation of points in multidimensional spaces that, theoretica...

In class-modelling problems, which are again becoming increasingly important, there are two parameters to value the quality of the class-model built for a category, namely sensitivity and specificity. Using them as criteria, in this paper, two different approaches to class-modelling problems are presented, approaches that differ from other usual me...

Uncertainty is inherent in all experimental determinations. Nevertheless, these measurements are used to make decisions including the performance of the own measurement systems. The link between the decision and the true implicit system that generates the data (measurement system, production process, category of samples, etc.) is a representation o...

To prevent possible frauds and give more protection to companies and consumers it is necessary to control that the types of milk used in the elaboration of dairy products correspond to those appearing in their label. Therefore, it is greatly interesting to have efficient, quick and cheap methods of analysis to identify them. In the present work, th...

Screening methods are used to detect the presence of a substance or class of substances at the level of interest and are specifically designed to avoid false compliant results. They should allow the running of a high number of samples per day at a low cost under routine conditions. In this work, a rapid and simple method for the screening of six su...

The objective of this work is to optimize a solid-phase extraction procedure for the simultaneous determination of sulfadiazine, sulfamerazine, and sulfamethazine in milk by fluorimetric detection. For this task, an alternative strategy is employed, which allows one to reduce noticeably the number of experiments without losing the quality of the es...

On many occasions, a system (an industrial process, a method of analysis, a synthesis, etc.) is in operation and the researcher wonders about the possibility of improving the results by only changing the values of the parameters that control the operation of the system. This demands exploration of an admissible region of the space where the paramet...