Novel fast identification and determination of free polyphenols in untreated craft beers by HPLC-PDA-ESI-MS/MS in SIR mode

Many analytical methods for polyphenol determination in food and beverages can be found in the literature, but mostof them need time-consuming sample pretreatment. Conversely, methods are missing for a rapid screening of non-pre-treatedsamples, with useful application in the agri-food industry, from process control to fraud. Selected ion recording mass mode afterliquid chromatographic separation was used for the detection and quantification of free polyphenols in three craft beers, after justdegassing, filtering, and diluting the beer samples with the mobile phase prior to the analysis. Fourteen polyphenols includinghydroxybenzoic acids, hydroxycinnamic acids, and flavonols were chosen as standards. Nine of them were identified and quantifiedin at least one of the analyzed craft beers, despite the low content and the complexity of the samples. Depending on the analyte, 80−7 μg/L as the limit of detection (LOD) and 240−30 μg/L as the limit of quantification (LOQ) were found. Satisfactory results forinterday and intraday precisions, accuracy, recovery, and matrix effect were found. The one-factor analysis of variance (ANOVA) onthe three different craft beers was statistically significant, with P < 0.05. The electrospray ionization mass fingerprinting of the samenon-pre-treated craft beers was also investigated for wider characterization. Diagnostic ions were found and identified as derivingfrom oligosaccharides, organic acids, and amino acids.