Aspergillus carbonariusis known to produce the carcinogenic ochratoxin A (OTA) in grapes. The metabolism process before OTA biosynthesis influences the content and composition of the volatile compounds in grapes. In this study, a self-established method based on QuEChERS coupled with high-performance liquid chromatography–fluorescence detection (HPLC-FLD) was used to determine the OTA levels during a seven-day contamination period. The results showed that OTA was detected on the second day after contamination withA. carbonarius. Thus, the first day was considered as the critical sampling timepoint for analyzing the volatiles in grapes before OTA biosynthesis. Additionally, the volatile compounds in grapes were analyzed using headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS) and dispersive liquid–liquid microextraction gas chromatography–mass spectrometry (DLLME-GC-MS). The corresponding data were evaluated via multivariate data analysis using projection methods, including PCA and OPLS-DA. The results indicated significant differences in the nine volatile compounds in grapes contaminated withA. carbonariusbefore OTA biosynthesis. The results of the Pearson correlation analysis showed positive correlations between ethyl acetate, styrene, 1-hexanol and OTA; (E)-2-hexenal and nerolic acid were negatively correlated with OTA. Overall, these findings provide a theoretical basis for the early prediction of OTA formation in grape and grape products using GC-MS technology.Keywords:volatile compounds;Ochratoxin A;QuEChERS-HPLC-FLD;HS-SPME-GC-MS;DLLME-GC-MS;OPLS-DA
Prolonged use of cosmetics containing banned fluoroquinolones can cause skin disorders and increase drug resistance. The QuEChERS method holds considerable application prospect in the pretreatment of cosmetic samples. Although octadecyl (C 18 )-bonded silica sorbent is commonly used as a QuEChERS clean-up material, the conventionally commercially available bulk C 18 sorbent is relatively costly and has a limited purification mechanism. In this study, using dendritic silica sphere (dSiO 2 ) as the substrate, and through the condensation reaction between cyanuric chloride (CNCl) and the amino group, a dNSiO 2 -CNCl-C 18 sorbent was synthesized. The sorbent was characterized using infrared spectroscopy, transmission electron microscopy, surface area and pore size analysis, and water contact angle measurements. The experimental results regarding the matrix removal from the model cosmetic lotion showed that dNSiO 2 -CNCl-C 18 exhibited a higher matrix removal efficiency compared to a commercial C 18 sorbent. Furthermore, a QuEChERS-HPLC-FLD method was developed using dNSiO 2 -CNCl-C 18 for the simultaneous detection of four fluoroquinolones, norfloxacin (NOR), pefloxacin (PEF), enrofloxacin (ENR), and difloxacin (DIF). The linear ranges were 0.10 to 100.0 μg L −1 for NOR and PEF, and 0.05 to 100.0 μg L −1 for ENR and DIF, with coefficient of determination exceeding 0.999. Satisfactory spiked recoveries for the lotion sample ranged from 91.5% to 107.0%, with intra-day and inter-day precision values not exceeding 7.6%. The established method was subsequently validated through its successful application in additional cream and emulsion samples. dNSiO 2 -CNCl-C 18 exhibits low synthesis costs and demonstrates promising potential for matrix purification in various complex samples, facilitating the rapid determination of target compounds.
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