Abstract: An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was established for the analysis of seven phenolic acids in wax apple fruit. The separation was performed on a Waters CORTECD? T3 (2.1 mm × 100 mm, 2.7 μm) column, and the column temperature was set at 30 ℃. The mobile phase consisted of 0.1% formic acid aqueous solution and acetonitrile at a 0.3 mL/min flow rate. The samples were extracted twice with acetonitrile, and the external standard method was used for quantitative detection of the phenolic acids. Results showed that the standard calibration curves had a good linear relationship in the range of 5.0–1 000 ng/mL with correlation coefficients equal to or larger than 0.996 1. The recoveries of spiked samples ranged from 93.6% to 98.8%, with relative standard deviation (RSD) from 1.9% to 7.5%. The limits of detection were 0.3–2.7 μg/kg, and the limits of quantification were 1.0–5.0 μg/kg. This method was used to determine phenolic acids in wax apple fruit, and the obtained data were analyzed by principal component analysis (PCA). Three principal components were obtained and used as the independent variables for proposing a mathematical model. The comprehensive F value was negative on the 6th day of storage, indicating that a large number of phenolic acids had begun to decompose. In conclusion, the established method is simple, sensitive, stable, reliable, and suitable for the quality evaluation of wax apple.

Key words: ultra-high performance liquid chromatography-tandem mass spectrometry; phenolic acids; wax apple; determination