Third- and fourth-order data generation and modeling and their application in the analysis of complex systems

M.R. ALCARAZ; M. MONTEMURRO; F. CHIAPPINI; E. MORZAN; M.J. CULZONI; A. MUÑOZ DE LA PEÑA; H.C. GOICOECHEA

Estambul

Congreso; Euroanalysis; 2019

Over the last years, several analytical applications based on multiway calibration have been developed aiming to improve the performance of the methodologies by exploiting the benefits offered by the higher-order data modeling. In this regard, it is noticeable that third- and fourth-order data-based analytical methods are still scarce despite all the aids that have been already demonstrated [1]. For instance, a) the possibility of decomposing a unique data array for each sample; b) the enhancement of the analytical figures of merit and c) the possibility to tackle collinearity problems arisen from the introduction of an extra mode, are included among the benefits that have been proved and represent the so-called ?third-order advantage?. This topic has been a matter of debate among the scientific community and has promoted intensive research towards unravelling its existence and true nature. In this work, different applications focused on third-order excitation-emission fluorescence matrices (EEM)-based data are described. Instrumental configurations, data generation and data modeling are depicted. First, a chromatographic procedure coupled to on-line EEM acquisition was developed for the analysis of emergent contaminant in aqueous environmental samples. With this approach, it was possible to acquire 25 sequential EEM for a given chromatographic run. Neither chromatographic flow stop nor fraction collection after chromatographic procedure were required. However, to the best of our knowledge, there is no chemometric algorithm capable to model this kind of data by virtue of the strong dependence between instrumental modes. Thus, an algorithm based on Tucker 3 decomposition is proposed as alternative to model non-trilinear/quadrilinear 4-way data. In order to provide evidences of the real existence of the third-order advantage, a system consisting on the determination of 3 analytes with identical fluorescence spectra by means of the photodegradation kinetics was developed. For this purpose, the photodegradation of the analytes was monitored by EEM in different UV-irradiation periods of time. Then, the three possible second-order calibration models were compared against the third-order calibration model in terms of predictive capability, figures of merit and retrieved spectral profile evaluation. Last, study of the evolution of a cell culture registering EEMs. A sterile sample from standard etanercept (Et) process was acquired daily for viable cells count and determination of Et concentration in supernatant by standard off-line univariate techniques. EEM were simultaneously obtained (second-order data) and then arranged in a third-order structure. The later was alternatively modeled by different chemometric algorithms. Firstly, unsupervised decomposition methods Parallel Factor Analysis (PARAFAC) and Multivariate Curve Resolution (MCR) were considered to qualitatively analyse the spectral information. PARAFAC components were putatively related to biological fluorophores present in the culture media during fermentation of CHO cells (aromatic aminoacids, pyridoxine, flavin, folic acid and NAD) demonstrating that a proper modeling of a three-way array corresponding to a single fermentation process, allows extracting extremely useful information about it. [1] G.M. Escandar, H.C. Goicoechea, A. Muñoz de la Peña, A.C. Olivieri, Second- and higher-order data generation and calibration: A tutorial. Anal. Chim. Acta 806 (2014) 8? 26.