Determination of Phenolic Compounds in Paprika by Ultrahigh Performance Liquid Chromatography–Tandem Mass Spectrometry: Application to Product Designation of Origin Authentication by Chemometrics

Abstract

A UHPLC-ESI-MS/MS method was developed for the determination of 36 phenolic compounds in paprika. The proposed method showed good method performance with limits of quantitation between 0.03-50 µg/L for 16 compounds, and between 50 µg/L and 1 mg/L for 12 compounds. Good linearity (r 2 > 0.995), run-to-run and day-today precisions (%RSD values <12.3% and <19.2%, respectively), and trueness (relative errors <15.0%) were obtained. The proposed method was applied to the analysis of 111 paprika samples from different production regions: Spain (La Vera PDO and Murcia PDO) and Czech Republic, each one including different flavor varieties (sweet, bittersweet, spicy). Phenolics profiles and concentration levels showed to be good chemical descriptors to achieve paprika classification and authentication according to the production region by principal component analysis (PCA) and partial least squares regressiondiscriminant analysis (PLS-DA). In addition, perfect classification among flavor varieties for Murcia PDO and Czech Republic samples was also obtained.

Classification and Authentication of Paprika by UHPLC-HRMS Fingerprinting and Multivariate Calibration Methods (PCA and PLS-DA)

“…Full scan HRMS spectra (m/z 100-1500) at a mass resolution of 70.000 FWHM (full-width at half maximum, at m/z 200) was employed to register the UHPLC-HRMS metabolomics fingerprints, with an automatic gain control (AGC) target (which is the number of ions to fill the instrument C-Trap) of 2.5 × 10 5 , and a maximum injection time of 200 ms. UHPLC-HRMS system control and data processing were performed using Xcalibur version 3.1 software (Thermo Fisher Scientific). Samples were extracted following a previously proposed procedure [1,19]. Briefly, paprika samples (0.3 mg) were extracted with water:acetonitrile 20:80 v/v solution (3 mL) by stirring (1 min) with a vortex mixer (Stuart, Sone, UK), and by sonication (15 min) with an ultrasonic bath (2510 Branson, Hampton, NH, USA).…”

“…For that purpose, 105 paprika samples belonging to different PDO and production regions (La Vera PDO, Murcia PDO, and the Czech Republic), all of them including samples with different taste varieties, were analyzed. A simple and generic sample extraction method using water:acetonitrile 20:80 (v/v) as extracting solvent was proposed [1,19,22,23]. Reversed-phase UHPLC on a C18 column under universal gradient elution with water and acetonitrile (both of them with 0.1% formic acid) as mobile phase components were selected for the chromatographic separation.…”

Targeted UHPLC–HRMS (Orbitrap) Polyphenolic and Capsaicinoid Profiling for the Chemometric Characterization and Classification of Paprika with Protected Designation of Origin (PDO) Attributes

“…As previously commented, the present work aimed to develop a targeted-UHPLC-HRMS profiling method to obtain discriminant paprika chemical descriptors that able to address sample classification regarding both the paprika production region (and PDO) and the paprika flavor variety. For this purpose, the paprika samples were analyzed through reversed-phase chromatography using a C18 column under universal gradient elution, with water and acetonitrile (both with 0.1% formic acid) as the mobile phase components, after a simple sample extraction with water:acetonitrile 20:80 (v/v), as previously reported [28,29,46]. As an example, Figure 1 shows the UHPLC-HRMS total ion chromatograms and the selected ion chromatogram for the ferulic acid (m/z 193.0506) of three selected sweet paprika samples belonging to different production regions (La Vera PDO, Murcia PDO, and the Czech Republic).…”

“…At present, there are several methods for the determination of polyphenolic and phenolic compounds, such as global assays for the evaluation of the total content by colorimetric or fluorimetric methods, or more specific ones, based on separation by capillary electrophoresis, liquid chromatography, and gas chromatography. However, liquid chromatography with UV or electrochemical detection, or that coupled with mass spectrometry is nowadays the technique of choice [17,[23][24][25][26][27][28][29][30][31][32]. However, the great chemical diversity among this family of compounds and the range of concentrations in which they can be found make liquid chromatography coupled with high-resolution mass spectrometry (LC-HRMS) the most effective technique.…”

“…Both targeted and non-targeted (fingerprinting) methodologies-some in combination with multivariate chemometric methods such as principal component analysis (PCA) and partial least squares regression-discriminant analysis (PLS-DA) have been proposed to address paprika classification and authentication issues [13,29,[39][40][41][42][43][44][45][46]. As an example, we recently proposed a UHPLC-MS/MS method, using a triple quadrupole instrument for the determination of 36 polyphenols and phenolic compounds in paprika samples, which was applied to PDO authentication by PCA and PLS-DA [28]. Although in general a good sample discrimination regarding the production region was observed, the targeted monitoring of these 36 compounds was not good enough to achieve the discrimination of La Vera Paprika samples as a function of the flavor variety (sweet, bittersweet, and spicy).…”