关键词: 茄科蔬菜, 茄碱, MOF-808, 超高效液相色谱-串联质谱法, 分散固相萃取

Abstract: α-Solanine and α-chaconine are natural secondary metabolites produced by plants. They exhibit neurotoxicity, gastrointestinal toxicity, teratogenicity, and other adverse effects. These two alkaloids are widely present in solanaceous vegetables such as potato, tomato, and eggplant, posing a threat to food safety. Owing to the complex matrix of solanaceous vegetables, the establishment of a highly selective and sensitive analytical method is of great significance for food safety supervision and risk assessment. In this study, a metal-organic framework MOF-808 adsorbent was synthesized by a solvothermal method, and a dispersive solid-phase extraction （d-SPE） pretreatment method was established based on this adsorbent. By virtue of the selective adsorption of MOF-808 toward impurities in sample extracts to mitigate matrix interference, combined with ultra-high performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）, a method for the accurate quantitative analysis of α-solanine and α-chaconine in solanaceous vegetables was developed. The structure, surface morphology and specific surface area of the MOF-808 adsorbent were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and BET nitrogen adsorption. The characterization results confirmed that the as-synthesized MOF-808 exhibited a regular octahedral structure and uniform particle size. The average specific surface area and pore size were 2 386.5 m²/g and 1.72 nm, respectively. These properties gave it excellent adsorption performance. The effects of MOF-808 dosage （5, 10, 15, 20, 25 and 30 mg）, ultrasonic dispersion time （1, 2, 3, 4 and 5 min）, and vortex adsorption time （2, 4, 6,, 8 and 10 min） were investigated. After optimization, the optimal conditions were determined as follows： adsorbent dosage of 10 mg, dispersion time of 4 min, and adsorption time of 8 min. Each sample （2.0 g） was individually weighed and transferred to a 50 mL centrifuge tube containing 10 mL of 75% （volume fraction） ethanol. Then, 0.5 g of MgSO₄ and 0.5 g of NaOAc were added. The solution was shaken vigorously by hand for 30 s, ultrasonicated for 30 min, vortexed for 30 min and centrifuged at 8 000 r/min for 5 min. Afterwards, 1 mL of the supernatant was dried under nitrogen and reconstituted with 1 mL of methanol-water （2∶8, volume ratio）. Then 10 mg of MOF-808 adsorbent was added, ultrasonicated for 4 min to disperse, vortexed for 8 min for adsorption and centrifuged at 12 000 r/min for 5 min. The purified supernatant was filtered through a 0.22 μm nylon membrane before analysis. Analyte separation was accomplished on an Xbridge BEH C18 column （100 mm×3.0 mm,2.5 μm） using a mobile phase consisting of 5 mmol/L ammonium acetate in water containing 0.1% formic acid and acetonitrile, and quantification was conducted by the external standard method. Method validation results demonstrated that α-solanine and α-chaconine exhibited excellent linearity within their respective concentration ranges, with correlation coefficients （R²） all exceeding 0.99. The limits of detection （LODs） and limits of quantification （LOQs） were within the ranges of 0.02-0.10 μg/kg and 0.05-0.30 μg/kg, respectively. At three spiking levels （low, medium, and high）, the recoveries of the two analytes varied from 84.6% to 105.9%, with relative standard deviations （RSDs） all less than 20.0%. The intra-day precision and inter-day precision were 1.8%-4.9% and 2.7%-6.2%, respectively. The established method was applied to the analysis of α-solanine and α-chaconine in solanaceous vegetables. Neither α-solanine nor α-chaconine was detected in tomato samples; trace levels were detected in eggplant samples, while the detection rate reached 100% in potato samples, with the total glycoalkaloid content （α-solanine + α-chaconine） in some samples exceeding the standard limit. Notably, the proposed method integrates high efficiency, sensitivity, and reliability, making it a promising analytical tool for the routine determination of α-solanine and α-chaconine in solanaceous vegetables （potato, tomato, and eggplant）.

Key words: solanaceous vegetables, solanine, MOF-808, ultra-high performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS）, dispersive solid-phase extraction （d-SPE）