Anna De Juan

University of Barcelona | UB · Department Analytical Chemistry

The unmixing of multiexponential decay signals into monoexponential components using soft modelling approaches is a challenging task due to the strong correlation and complete window overlap of the profiles. To solve this problem, slicing methodologies, such as PowerSlicing, tensorize the original data matrix into a three-way data array that can be...

Industrially tempered dark chocolate processed under different conditions was analyzed using Attenuated Total Reflection-Fourier Transform-Infrared spectroscopy (ATR-FT-IR). Spectra were collected during the cooling process right after tempering using two distinct machines and machine operational modes and over short and long storage (1 day and two...

Laser-induced breakdown spectroscopy (LIBS) imaging is a powerful and innovative technique with a constant increasing success and interest in many scientific fields. Using LIBS imaging, it is possible to highlight the presence of atoms in complex samples of different nature to achieve important spectral and spatial information. Simple preparation o...

Synchronization of variable trajectories from batch process data is a delicate operation that can induce artifacts in the definition of multivariate statistical process control (MSPC) models for real-time monitoring of batch processes. The current paper introduces a new synchronization-free approach for online batch MSPC. This approach is based on...

Laser-induced breakdown spectroscopy (LIBS) imaging is an innovative technique that associates the valuable atomic, ionic and molecular emission signals of the parent spectroscopy with spatial information. LIBS works using a powerful pulse laser as excitation source, to generate a plasma exhibiting emission lines of atoms, ions and molecules presen...

Hyperspectral imaging (HSI) is a useful non-invasive technique that offers spatial and chemical information of samples. Often, different HSI techniques are used to obtain complementary information from the sample by combining different image modalities (Image Fusion). However, issues related to the different spatial resolution, sample orientation o...

Tessellated cartilage is a distinctive composite tissue forming the bulk of the skeleton of cartilaginous fishes (e.g. sharks and rays), built from unmineralized cartilage covered at the surface by a thin layer of mineralized tiles called tesserae. The finescale structure and composition of elasmobranch tessellated cartilage has largely been invest...

Controlling blending processes of solid material using advanced real-time sensing technologies tools is crucial to guarantee the quality attributes of manufactured products from diverse industries. The use of process analytical technology (PAT) tools based on chemical imaging systems are useful to assess heterogeneity information during mixing proc...

Hyperspectral imaging (HSI) is a useful non-invasive technique that offers spatial and chemical information of samples. Often, different HSI techniques are used to obtain complementary information from the sample by combining different image modalities (Image Fusion). However, issues related to the different spatial resolution, sample orientation o...

Multivariate Curve Resolution (MCR) covers a wide span of algorithms designed to tackle the mixture analysis problem by expressing the original data through a bilinear model of pure component meaningful contributions. Since the seminal work by Lawton and Sylvestre in 1971, MCR methods are dynamically evolving to adapt to a wealth of diverse and dem...

A copper smelter generates solutions containing H2SO4 (220 ± 10 g/L), non-metals (3.4 ± 0.2 g/L As) and metals (0.5 ± 0.1 g/L Zn, 0.13 ± 0.01 g/L Fe and 0.11 ± 0.01 g/L Cd) that are treated with lime as disposal option. In order to promote circularity, the recovery of H2SO4 by diffusion dialysis (DD) was evaluated with a lab-stack unit containing A...

Heterogeneity characterization is crucial to define the quality of end products and to describe the evolution of processes that involve blending of compounds. The heterogeneity concept describes both the diversity of physicochemical characteristics of sample fragments (constitutional heterogeneity) and the diversity of spatial distribution of the m...

Recent advances in the latest generation of MEMS (micro-electro-mechanical system) Fabry-Pérot interferometers (FPI) for near infrared (NIR) wavelengths has led to the development of ultra-fast and low cost NIR sensors with potential to be used by the process industry. One of these miniaturised sensors operating from 1350 to 1650 nm, was integrated...

The effect of physicochemical factors and use of skim milk powder on milk rennet-coagulation was investigated combining near infrared (NIR) spectroscopic monitoring and Multivariate Curve Resolution - Alternating Least Squares (MCR-ALS). Coagulum formation has been studied by reference approaches (Formagraph and fundamental rheology) and with NIR s...

Image fusion is often oriented to solve differences in spatial scale and orientation among different spectroscopic platforms. However, an additional problem arises when the nature of the spectroscopic information differs in dimensionality as well. Indeed, most imaging systems, e.g., Raman, IR, MS,… allow acquisition of 3D images, with a linear spec...

PurposeThe current trend for continuous drug product manufacturing requires new, affordable process analytical techniques (PAT) to ensure control of processing. This work evaluates whether property models based on spectral data from recent Fabry–Pérot Interferometer based NIR sensors can generate a high-resolution moisture signal suitable for proce...

Formation of extractive-rich heartwood is a process in live trees that make them and the wood obtained from them more resistant to fungal degradation. Despite the importance of this natural mechanism, little is known about the deposition pathways and cellular level distribution of extractives. Here we follow heartwood formation in Larix gmelinii va...

Process analytical technologies (PAT) applied to process monitoring and control generally provide multiple outputs that can come from different sensors or from different model outputs generated from a single multivariate sensor. This paper provides a contribution to current data fusion strategies for the combination of sensor and/or model outputs i...

In this article, the extension of the Multivariate Curve Resolution Alternating Least Squares (MCR-ALS) method to the simultaneous analysis of multiple data sets bearing information in common is presented. The basic assumption in this extension of MCR methods is the fulfillment of a common bilinear model for the simultaneously analyzed data sets, w...

This article introduces the general concepts of multivariate curve resolution (MCR). The key concepts of the curve resolution problem and the general features of MCR reported in the literature are described. Basic approaches to find the underlying pure component responses are outlined, and these are based on using either a rotation matrix or iterat...

Data modeling is a wide concept that exists since long and encompasses all possible ways to interpret the information associated with a process, analytical measurement or set of related parameters that presents a systematic variation. Data modeling can follow the path of knowledge and be based on first principles or can focus on measurements and em...

Intratumour heterogeneity due to cancer cell clonal evolution and microenvironment composition and tumor differences due to genetic variations between patients suffering of the same cancer pathology play a crucial role in patient response to therapies. This study is oriented to show that matrix-assisted laser-desorption ionization-Mass spectrometry...

Recently, the presence of i-motif structures at C-rich sequences in human cells and their regulatory functions have been demonstrated. Despite numerous steady-state studies on i-motif at neutral and slightly acidic pH, the number and nature of conformation of this biological structure are still controversial. In this work, the fluorescence lifetime...

The characterization of cancer tissues by matrix-assisted laser desorption ionization-mass spectrometry images (MALDI-MSI) is of great interest because of the power of MALDI-MS to understand the composition of biological samples and the imaging side that allows for setting spatial boundaries among tissues of different nature based on their composit...

Image fusion encloses all data analysis strategies aiming at combining the information of several images obtained with the same platform or by different spectroscopic platforms. Image fusion can imply building a single multiset or multiway structure with all images involved or connecting the related individual images through regression models. In a...

Data fusion implies often the concatenation of data sets that present an enormous diversity in terms of information, size, and behavior. The pieces of information connected reflect the variation apportioned by components, events, or sources that are differently represented and, yet, complement each other in the data blocks analyzed simultaneously....

The use of hyperspectral imaging techniques in biological studies has increased in the recent years. Hyperspectral images (HSI) provide chemical information and preserve the morphology and original structure of heterogeneous biological samples, which can be potentially useful in environmental –omics studies when effects due to several factors, e.g....

Description of the formation of i-motif structures by a sequence found near the promoter region of a gene by means of spectroscopic techniques, separation methods, and chemometric analysis

The i-motif is a DNA structure formed by cytosine-rich sequences, very relevant from a biochemical point of view and potentially useful in Nanotechnology as pH-sensitive nanodevices or nanomotors. To provide a different view on the structural changes and dynamics of direct excitation processes involving i-motif structures, the use of rapid scan FTI...

Background Plant cell walls are nanocomposites based on cellulose microfibrils embedded in a matrix of polysaccharides and aromatic polymers. They are optimized for different functions (e.g. mechanical stability) by changing cell form, cell wall thickness and composition. To reveal the composition of plant tissues in a non-destructive way on the mi...

Data fusion of different imaging techniques allows a comprehensive description of chemical and biological systems. Yet, joining images acquired with different spectroscopic platforms is complex due to the different sample orientation and image spatial resolution. Whereas matching sample orientation is often solved by performing suitable affine tran...

Raman spectroscopy (RS) has shown promise as a tool to reveal biochemical changes that occur in cancer processes at the cellular level. However, when analysing clinical samples, RS requires improvements to be able to resolve biological components from the spectra. We compared the strengths of Multivariate Curve Resolution (MCR) versus Principal Com...

Raman images were used to study the effect of the contaminant chlorpyriphos‐oxon on zebrafish eye samples. Multivariate Curve Resolution‐Alternating Least Squares (MCR‐ALS) was used to obtain the distribution maps and spectral signatures of biological components present in the images analyzed. The use of MCRALS spectral signatures as starting infor...

This work does a systematic comparative evaluation of 2 methods originating from different fields, both dedicated to the problem of curve resolution/unmixing: multivariate curve resolution–alternating least squares (MCR-ALS) and band-target entropy minimization (BTEM). The MCR-ALS factorizes the data matrix into spectral and concentration profiles...

Hyperspectral images provide spatial and structural information on samples. This article aims at providing an overview on hyperspectral image analysis research trends, mainly focusing on specific aspects related to this kind of analytical measurement, such as the global/local and the spectral/spatial dualities, the hurdles associated with image fus...

The study of pollutant effects on living organisms provides information about the possible biological and environmental response to a contaminant. Progression of prostate cancer may be related to exposure to pesticides or other chemical substances. In this work, the effect of the pesticide aldrin on human prostate cancer cells (DU145) is studied us...

Changes on an organism by the exposure to environmental stressors may be characterized by hyperspectral images (HSI), which preserve the morphology of biological samples, and suitable chemometric tools. The approach proposed allows assessing and interpreting the effect of contaminant exposure on heterogeneous biological samples monitored by HSI at...

The use of sparseness in chemometrics is a concept that has increased in popularity. The advantage is, above all, a better interpretability of the results obtained. In this work, sparseness is implemented as a constraint in multivariate curve resolution - alternating least squares (MCR-ALS), which aims at reproducing raw (mixed) data by a bilinear...

The use of multivariate unmixing/resolution methods for the analysis of biological vibrational hyperspectral images is crucial to characterize the morphology and spectral signatures of the different biological tissues or cell compartments. This work provides a general data analysis protocol to interpret Raman and FT-IR hyperspectral images of biolo...

Cytosine-rich oligonucleotides are capable of forming complex structures known as i-motif with increasingly studied biological properties. The study of sequences prone to form i-motifs located near the promoter region of genes may be difficult because these sequences not only contain repeats of cytosine tracts of disparate length but also these may...

This article describes a non-destructive analytical method developed to solve forensic document examination problems involving crossed lines and obliteration. Different strategies combining confocal Raman imaging and multivariate curve resolution-alternating least squares (MCR-ALS) are presented. Multilayer images were acquired at subsequent depth...

Hyperspectral images collected with different spectroscopic techniques can be combined to benefit from complementary information and to improve the general description of chemical systems. The simultaneous analysis of images collected by different spectroscopic platforms can only be carried out when images are spatially matched with each other (i.e...

Near infrared spectroscopy in-line monitoring and modelling of soybean oil methanolysis has been done using multivariate curve resolution alternating least squares (MCR-ALS) with correlation constraint. This constraint allows for quantitation of the methyl ester formed with little calibration effort and the MCR model provides additionally a general...

Electron paramagnetic resonance (EPR) spectroscopy is a powerful technique that is able to characterize radicals formed in kinetic reactions. However, spectral characterization of individual chemical species is often limited or even unmanageable due to the severe kinetic and spectral overlap among species in kinetic processes. Therefore, we applied...

The chapter describes the algorithm multivariate curve resolution-alternating least squares (MCR-ALS), paying special attention to applications to analyze spectroscopic data. The main application fields addressed are process and image analysis. A brief comment on the specific use of MCR for quantitative analysis is done. Finally, a small note on ho...

This chapter starts describing the basics of Multivariate Curve Resolution, including the modus operandi, description of constraints and use for analysis of single data sets and multiset analysis. An exhaustive section is devoted to the use of MCR for quantitative purposes. In this last part, classical extraction of quantitative information in seco...

During the last 40 years, Multivariate Curve Resolution (MCR) has emerged as a powerful tool to investigate (bio) chemical data sets. MCR has evolved from the analysis of a single data set to multiset and multiway data analysis. MCR has been extended to the investigation of new application domains and of more challenging problems. MCR is achieving...

Raman chemical imaging provides chemical and spatial information about pharmaceutical drug product. By using resolution methods on acquired spectra, the objective is to calculate pure spectra and distribution maps of image compounds. With multivariate curve resolution-alternating least squares, constraints are used to improve the performance of the...

This paper shows the application of Raman and infrared hyperspectral imaging combined with multivariate curve resolution (MCR) to the analysis of the constituents of commercial chocolate samples. The combination of different spectral data pretreatment methods allowed decreasing the high fluorescent Raman signal contribution of whey in the investiga...

A calcium fluoride (CaF2) plate was exposed to pulsed laser irradiations inducing surface morphological and ionization changes on its surface. More precisely surface damages mainly correspond to intrinsic defects. Electron paramagnetic reso-nance (EPR) hyperspectral imaging is a powerful technique able to characterize the defects formed on the CaF2...

Raman and Fourier transform IR (FTIR) microspectroscopic images of biological material (tissue sections) contain detailed information about their chemical composition. The challenge lies in identifying changes in chemical composition, as well as locating and assigning these changes to different conditions (pathology, anatomy, environmental or genet...

The objective of this work is assessing whether the combination of Raman spectroscopy and chemometric tools is appropriate to differentiate blue ballpoint pen inks. Fourteen commercial blue ballpoint pen inks from different brands and models were studied and Raman spectra were obtained on ink lines written on A4 sulfite paper. First, a study of the...

In this work, we study the gel formation dynamics after shear rejuvenation of a laponite colloidal model system using near infrared (NIR) spectroscopy. The aim of this study is to investigate the ability of NIR spectroscopy combined with hybrid hard- and soft-modelling based on multivariate curve resolution-alternating least squares (MCR-ALS) analy...

We emphasize the potential of soft-modeling multivariate curve resolution method to extract pure difference spectra and kinetic profiles from data sets obtained by femtosecond transient absorption experiments. The example of the photo-switching of photochromic salicylidene aniline after 266 nm excitation will be detailed.

An updated version of the graphical user-friendly interface related to the Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) algorithm is presented. This GUI works under MATLAB (R) environment and includes recently published advances of this algorithm linked to the implementation of additional constraints, such as kinetic hard-model...

This article is a tutorial that focuses on the main aspects to be considered when applying Multivariate Curve Resolution to analyze multicomponent systems, particularly when the Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) algorithm is used. These aspects include general MCR comments on the potential fields of application and c...

The development of a method based on the combination of excitation–emission fluorescence matrices (EEMs) and second‐order algorithms is proposed to identify and quantify 10 polycyclic aromatic hydrocarbons (PAHs) in extracts of aerosol samples, a particularly complex sample matrix because of the low amount of PAHs and the numerous fluorescent inter...

Polymorphism is often encountered in many crystalline compounds. To control the quality of the products, it is relevant knowing the potential presence of polymorph transformations induced by different agents, such as light exposure or temperature changes. Raman images offer a great potential to identify polymorphs involved in a process and to accur...