Characterization of non-volatile chemical constituents in Thai wineusing liquid chromatography-tandem mass spectrometry

Abstract

In this work, high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed and validated for simultaneous determination of targeted non-volatile compounds, such as five organic acids and twenty phenolic compounds, in 19 wine samples including 2 imported red wines, 15 Thai red wines and 2 fruit wines, using the following HPLC-MS/MS conditions: a C18 analytical column and gradient elution of A: B mobile phase at flow rate 0.4 mL/min, where A and B are 0.1% v/v formic acid in water and 0.1% v/v formic acid in methanol. The limit of detection (LOD) and the limit of quantitation (LOQ) for these targeted compounds were obtained in a range of 0.0084-0.48 mg/L and 0.026-1.45 mg/L, respectively. By spiking known concentration standards in diluted pooled wine samples, the acceptable accuracy and precision were obtained with 84.9% of 225 data sets falling in acceptable criteria in the range of 80-110% and along with %RSD of 0.4-7%. For real sample analysis, the phenolic compounds in all samples were found in a range of 0.00423-69.2 mg/L. The predominant phenolic compounds with the highest concentrations found in all samples include gallic acid, caftaric acid and (+)-catechin. The predominant organic acid compounds with the highest concentrations found in all samples include lactic acid, tartaric acid and succinic acid. Using a PCA approach, three clusters were observed. Cluster A including 12 Thai red wines from 3 origins, cluster B including 3 Thai red wines and 2 imported red wines, and cluster C including 2 fruit wines. The following significant compounds were identified in each cluster, syringic acid for cluster A, kaempferol for cluster B and citric acid and malic acid for cluster C. Therefore, HPLC-MS/MS analysis combined with PCA analysis be used for quality control and authentication of wine.