A simple, rapid and efficient methodology was developed and validated for the analysis of four Alternaria toxins in jujube: Tenuazonic acid, alternariol, alternariol monomethyl ether, and tentoxin. Under the optimized extraction procedure, chromatographic conditions, and instrumental parameters, the four toxins were effectively extracted via a quick, easy, cheap, effective, rugged, and safe (QuEChERS) method, and quantified by ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). Matrix-matched calibrations ranging from 0.01 to 0.5 μg mL-1 were conducted for the quantification due to the matrix effect. A blank jujube sample was spiked at 40, 80 and 160 μg kg-1, obtaining recoveries in the range of 83.5⁻109.6%. Limits of detection and limits of quantification were in the range of 0.14⁻0.26 and 0.47⁻0.87 μg kg-1, respectively. Finally, the developed method was applied for the quantification of the four toxins in 14 jujube samples, including black spot-infected and uninfected samples. Results showed that the predominant toxin detected in all the samples was tenuazonic acid, the content of which was associated with the infection level; alternariol, alternariol monomethyl ether, and tentoxin were detected in all the infected samples and some of the uninfected samples with rather low contents.
Keywords: Alternaria toxins; QuEChERS; UPLC-MS/MS; jujube.