Development of a QuEChERS-Based UHPLC-MS/MS Method for Simultaneous Determination of Six Alternaria Toxins in Grapes.

Wenbo Guo,Kai Fan,Dongxia Nie,Junhua Yang,Zheng Han,Jiajia Meng,Yuanyuan Shen,Qingwen Huang,Emmanuel K Tangni,Zhihui Zhao,Yongjiang Wu

doi:10.3390/toxins11020087

Wenbo Guo, Kai Fan + Show 9 more

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https://doi.org/10.3390/toxins11020087

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Abstract

A simple and reliable analytical method for the simultaneous determination of alternariol (AOH), altenuene (ALT), tentoxin (TEN), altenusin (ALS), tenuazonic acid (TeA), and alternariol monomethyl ether (AME) in grapes was developed by ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS). A modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure with the extraction by acetonitrile and purification by sodium chloride (0.5 g) and anhydrous magnesium sulfate (0.5 g) was established to recover the six Alternaria toxins. After validation by determining the linearity (R2 > 0.99), recovery (77.8–101.6%), sensitivity (limit of detection in the range of 0.03–0.21 μg kg−1, and limit of quantification in the range of 0.09–0.48 μg kg−1), and precision (relative standard deviation (RSD) ≤ 12.9%), the analytical method was successfully applied to reveal the contamination state of Alternaria toxins in grapes. Among 56 grape samples, 40 (incidence of 71.4%) were contaminated with Alternaria toxins. TEN was the most frequently found mycotoxin (37.5%), with a concentration range of 0.10–1.64 μg kg−1, followed by TeA (28.6%) and AOH (26.8%). ALT (10.7%), AME (3.6%), and ALS (5.4%) were also detected in some samples. To the best of our knowledge, this is the first report about the Alternaria toxins contamination in grapes in China.

Highlights

Alternaria toxins, secondary metabolites produced by Alternaria spp, e.g., A. alternata, A. tenuissima, and A. infectoria—are frequently found in cereals, fruits, and vegetables [1,2]
The major objective of this study is to develop a rapid and reliable ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for simultaneous determination of AOH, alternariol monomethyl ether (AME), ALT, ALS, TEN, and tenuazonic acid (TeA) based on a simple sample preparation of modified QuEChERS approach, and to explore the actual contamination situations of Alternaria toxins in grapes for the first time in the world
MS/MS parameters were optimized by flow injection analysis of an individual Alternaria toxin standard at a concentration of 50–200 ng mL−1

Summary

Introduction

Alternaria toxins, secondary metabolites produced by Alternaria spp, e.g., A. alternata, A. tenuissima, and A. infectoria—are frequently found in cereals, fruits, and vegetables [1,2]. The most important members include alternariol (AOH), alternariol monomethyl ether (AME), altenuene (ALT), altenusin (ALS), tentoxin (TEN), and tenuazonic acid (TeA) [3]. The European Food Safety Authority (EFSA) has established the threshold of toxicological concern (TTC) values as 2.5 ng kg−1 body weight per day for AOH and AME, and 1500 ng kg−1 for. Considering its widespread occurrence and intense toxicity, TeA, the most prevalent Alternaria toxin, has been registered as a toxic chemical by the Occupational Safety and Health Act (OSHA), and a maximal limit of 500 μg kg−1 was proposed by German federal state Bavaria in sorghum/millet-based infant food [11].

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