Rapid Determination of Furoquinoline Alkaloids in Rutaceae Species by Ultra-Performance Liquid Chromatography (UPLC) with Photodiode Array (PDA) and Electrospray Ionization–Quadrupole Time-of-Flight Mass Spectrometry (ESI-Q-TOF/MS)

A qualitative and quantitative method based on ultra-performance liquid chromatography (UPLC) and photodiode array (PDA) and electrospray ionization–quadrupole time-of-flight mass spectrometry (ESI-Q-TOF/MS) was developed, verified, and used to determine the quinoline alkaloids in Dictamnus dasycarpus and Zanthoxylum schinifolium, belonging to the Rutaceae family. Excellent analyte peak resolution was achieved on both quaternary and binary pumps by using acetonitrile and water containing 0.1% formic acid as the mobile phase using a C18 column. All alkaloids exhibited maximum absorption wavelength from 239 to 244 nm. The analytes were ionized as quasi-molecular ions [M + H]+ in MS and were characterized by using fragmentation ions formed by collision-induced dissociation (CID). This information was included in a library that was used to qualitatively identify alkaloids. The proposed method showed excellent linearity (r2 > 0.9988), limits of detection (PDA ≤ 25 ng/mL, MS ≤ 1.2 ng/mL), limits of quantification (PDA ≤ 75 ng/mL, MS ≤ 3.6 ng/mL), precision (in terms of relative standard deviation) of PDA ≤ 1.81% and MS 5.7%,. Liquid–liquid extraction (LLE) and solid-phase extraction (SPE) were conducted to separate and purify the alkaloids from the extracts. The analyte recoveries were determined to be PDA ≤ 103.11% and MS ≤ 104.45%. The method proceeded to deliver the comparable results for the determination of alkaloid components in samples. The developed UPLC-PDA and UPLC-ESI-Q-TOF/MS protocol facilitated the rapid, qualitative and quantitative identification of alkaloids in plants.