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.
An
innovative approach based on a surface functional monomer-directing
strategy for the construction of a sensitive and selective molecularly
imprinted electrochemical sensor for patulin recognition is described.
A patulin imprinted platinum nanoparticle (PtNP)-coated poly(thionine)
film was grown on a preformed thionine tailed surface of PtNP-nitrogen-doped
graphene (NGE) by electropolymerization, which provided high capacity
and fast kinetics to uptake patulin molecules. Thionine acted not
only as a functional monomer for molecularly imprinted polymer (MIP),
but also as a signal indicator. Enhanced sensitivity was obtained
by combining the excellent electric conductivity of PtNPs, NGE, and
thionine with multisignal amplification. The designed sensor displayed
excellent performance for patulin detection over the range of 0.002–2
ng mL–1 (R2 = 0.995) with a detection
limit of 0.001 ng mL–1 for patulin. In addition,
the resulting sensor showed good stability and high repeatability
and selectivity. Furthermore, the feasibility of its applications
has also been demonstrated in the analysis of real samples, providing
novel tactics for the rational design of MIP-based electrochemical
sensors to detect a growing number of deleterious substances.
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