Application of Fast Gas Chromatography–Mass Spectrometry in Combination with the QuEChERS Method for the Determination of Pesticide Residues in Fruits and Vegetables

A fast gas chromatography–mass spectrometry method has been developed for multiresidue determination of up to 56 pesticides in fruits and vegetables in a chromatographic run time of <10 min, using a single quadrupole mass spectrometer operating in selected ion monitoring mode. The well-known acetate-buffering version of the QuEChERS method has been used for sample preparation. Programmable temperature vaporizer injection of 3 μL allowed reaching limits of detection between 0.15 and 15 μg/kg for most compounds in the sample matrices tested. The applicability of the method has been evaluated in apple, orange, carrot, and tomato. Recoveries at three fortification levels (0.01, 0.1 and 0.5 mg/kg) ranged from 70 to 120 % for most compounds, with relative standard deviations below 20 % in all cases. The developed method has been applied to fruit and vegetable samples from different Spanish provinces.     

Evaluation of ability of ferulic acid to control growth and fumonisin production of Fusarium verticillioides and Fusarium proliferatum on maize based media

The aim of this study was to evaluate the efficacy of ferulic acid (1, 10, 20 and 25 mM) at different water activity (a_w) values (0.99, 0.98, 0.96 and 0.93) at 25 °C on growth and fumonisin production by Fusarium verticillioides and Fusarium proliferatum on maize based media. For both Fusarium species, the lag phase significantly decreased (p ≤ 0.001), and the growth rates increased (p ≤ 0.001) at the lowest ferulic acid concentration used (1 mM), regardless of the a_w. However, high doses of ferulic acid (10 to 25 mM) significantly reduced (p ≤ 0.001) the growth rate of both Fusarium species, regardless of the a_w. In general, growth rate inhibition increased as ferulic acid doses increased and as media a_w decreased. Fumonisin production profiles of both Fusarium species showed that low ferulic acid concentrations (1–10 mM) significantly increased (p ≤ 0.001) toxin production, regardless of the a_w. High doses of ferulic acid (20–25 mM) reduced fumonisin production, in comparison with the controls, by both Fusarium species but they were not statistically significant in most cases. The results show that the use of ferulic acid as a post-harvest strategy to reduce mycotoxin accumulation on maize needs to be discussed.     

Identification and quantification of leaf surface flavonoids in wild-growing populations of Dracocephalum kotschyi by LC–DAD–ESI-MS

Dracocephalum kotschyi Boiss. (Lamiaceae) is an aromatic and perennial herb endemic to Iran with interesting pharmacological and biological properties. The flavonoids luteolin-7-O-glucoside, apigenin-7-O-glucoside (cosmosiin), luteolin 3′-O-β-d-glucuronide, luteolin, apigenin, cirsimaritin, isokaempferide, penduletin, xanthomicrol, calycopterin and the polyphenol rosmarinic acid were identified among 13 natural populations of the plant by ESI–MS, LC–DAD and LC–DAD–ESI-MS. The plant extracts containing the identified compounds showed significant antioxidant activity, which was correlated with the flavonoid content. Additionally, leaf and stem size and geographical variability among the studied populations were correlated with flavonoid accumulation. Canonical correlation analysis was used to find a relationship between plant dimensions and phytochemical composition, and the plants with the lowest growth indices were found to have the highest levels of methoxylated flavonoids.