ENBIS Spring Meeting 2018

4 – 6 June 2018; Florence, Italy Abstract submission: 17 November 2017 – 20 April 2018

Exploring the Latent Variable Space of a Multiresponse DOE to Optimize Solid Phase Microextraction (SPME): Case study - Quantification of Volatile Fatty Acids in Wines

5 June 2018, 10:15 – 10:40


Submitted by
Marco P. Seabra dos Reis
Marco P. Seabra dos Reis (Department of Chemical Engineering, University of Coimbra), Ana Cristina Pereira (CIEPQPF, Department of Chemical Engineering, University of Coimbra), João M. Leça (Faculty of Exact Sciences and Engineering, University of Madeira), Pedro M. Rodrigues (Faculty of Exact Sciences and Engineering, University of Madeira), José C. Marques (Faculty of Exact Sciences and Engineering, University of Madeira)
In this work we apply Definitive Screening Designs (DSD) to optimize HS-SPME extraction in order to analyze volatile fatty acids (VFA) present in wine samples. The purpose is the simultaneous optimization of seven extraction parameters (responses – the chromatographic area of nine analytes). Both qualitative and quantitative extraction parameters (factors) were considered: a two-level qualitative variable, the fiber coating, and six quantitative variables, namely the pre-incubation time, the extraction time and temperature, the headspace/sample volume, the effect of agitation during extraction and the influence of the ethanol content. Optimization w.r.t. analytes’ chromatographic responses was carried out both individually (response by response) and altogether, by modelling the responses in the latent variable space (i.e., explicitly considering their underlying correlation structure). The analysis in the latent variable space was particularly informative, allowing the simultaneous optimization of the levels of the responses and also the robustness by which the best compromise is achieved. In the end, a consensus analysis of the two perspectives was considered in the definition of the overall optimal extraction conditions for the quantification of VFA in fortified wines. The solution found was to use a DVB/Car/PDMS fiber, 10 mL of samples in 20 mL vial, 40 min of extraction at 40 C. The analysis also revealed that the factors incubation time, agitation and sample dilution do not play a significant role in explaining the variability of extraction parameters. Therefore, they were set to the most convenient levels. This work demonstrates the benefits of using DOE and latent variable modelling for the optimization of analytical techniques, contributing to the implementation of rigorous, systematic and more efficient optimization protocols.

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