Validation of a 1D 1H-NOESY experiment for the analysis of wheat and pasta

Descrizione

Since 2012 Innovative Solutions S.r.l., a spin off company of the Polytechnic University of Bari, organizes NMR interlaboratory comparisons (ILCs) according to ISO/IEC 17043:2010 with the aim to promote the use of qNMR in official methods. The ILCs are organized by Innovative Solutions either for its own account or on behalf of third parties. In both cases, a scientific committee is responsible for the experimental design.

The first ILC was organized by Innovative Solutions on behalf of S.A.Mer. (Laboratory of the Chamber of Commerce of Bari). It indicated that NMR spectroscopy is a suitable tool for quantification of substances in standard calibration mixtures. The mixtures considered for the ILC were made of five components, four pesticides (Aldicarb, Methamidophos, Oxadixyl and Pirimicarb) and one reference molecule [3-(trimethylsilyl)-2,2,3,3-tetradeutero-propionic acid sodium salt (TSP)], dissolved in deuterated water. The concentrations of the pesticides in a test mixture were determined by using calibration lines developed at six concentration levels (including a blank sample). Slopes and intercepts of the calibration lines were obtained by plotting I_s/I_TSP (I_s being the intensity of the signal selected for the quantification of a given analyte and I_TSP being the intensity of the singlet generated by methyl protons of TSP) versus concentration of the analytes. It was demonstrated that the calibration lines developed by the different participants could be considered statistically equivalent.

Since, in principle, statistical equivalence of the calibration lines implies statistical equivalence of scaled NMR spectra, a second ILC was organized to confirm such an inference. In that case, aqueous extracts of wheat and flours were used as samples of a complex matrix. The outcomes further supported the statistical equivalence of the scaled NMR spectra and indicated a strong effect of processing procedures on the final results.

A third Interlaboratory Comparison aimed to validate an NMR method for metabolite quantification in wine grape juices. Different data pre-treatment approaches were considered, alongside the details of model validation. The primary goal was to provide a roadmap for data analysts to validate the distribution and reproducibility of NMR data from different instruments. The study also assessed the reproducibility of metabolite concentration in a grape juice sample, underscoring the importance of signal nature in achieving a high level of reproducibility.

This 4th Interlaboratory Comparison is organized in the framework of the project IPERDURUM Project title: “Filiera frumento duro: innovazione varietale, qualità e tracciabilità delle produzioni pugliesi”, CUP: B39J20000160009 funded by Regione Puglia under the Programma di Sviluppo Rurale (PSR) 2014-2020 Puglia – Misura 16 “Cooperazione” – Sottomisura 16.2 – “Sostegno a progetti pilota e allo sviluppo di nuovi prodotti, pratiche, processi e tecnologie” – DdS n. 94250037697.