Analyses of Total Alkaloid Extract ofCorydalis yanhusuoby Comprehensive RP × RP Liquid Chromatography with pH Difference

Abstract

A comprehensive two-dimensional (2D) reverse phase (RP) liquid chromatography (LC) method is developed for alkaloid analysis. This offline comprehensive 2D method is developed using different pH values. With a pH value of 10.5, most alkaloids appear in the form of neutral molecules possessing high retention factors based on their polarity, while the alkaloid polarity order is changed when the pH value decreased to 3.0. The performance of pH modulated 2D LC is demonstrated with 8 alkaloid standards which resulted in orthogonal separation. The developed method is then applied to total alkaloid separation in Corydalis yanhusuo. The first-dimension separation is carried out using methanol and water containing 1.0% ammonium hydroxide and a strong base-resistant RP column, which afforded a peak capacity of 94. The second-dimension analysis is carried out with a surface positive charge column providing a peak capacity of 205 using a mobile phase consisting of acetonitrile and water with 0.15% formic acid. 2D analyses of total alkaloid extract from C. yanhusuo afford a total peak capacity of 9090. Sixteen compounds were tentatively identified based on their ultraviolet spectrum and MS/MS analyses. The proposed method provides an alternative approach to achieve high peak capacity for analysis of alkaloid extract.

Liquid chromatographic separation of alkaloids in herbal medicines: Current status and perspectives

“…A common strategy to conduct 2D‐LC system is combining chromatographic systems with the same separation mode but different mobile phases. A comprehensive RP×RP LC with mobile phases at different pH values was established to separate alkaloids in extracts from the roots of Corydalis yanhusuo W. T. Wang [78]. High‐pH stable C 18 column and alkaline mobile phase were adopted in the first dimension while the second dimensional separation was performed on positive charge modified stationary phase and acidic eluent system.…”

Online high‐pH reversed‐phase liquid chromatography × low‐pH reversed‐phase liquid chromatography tandem electrospray ionization mass spectrometry combined with pulse elution gradient in the first dimension for the analysis of alkaloids in Macleaya cordata (willd.) R. Br

“…Br. was sensitive to pH value, which is mostly between 6 and 9 [11], even for the quaternary alkaloids. Therefore, if the mobile phase pH value was less than 6.0 and large than 9.0, respectively, it has a theoretically large difference in retention for alkaloids separated on RPLC.…”

“…[1,8]. However, due to the diverse structure and complex chemical composition of alkaloids, such 1D LC technology faces enormous challenges [11]. Comprehensive 2D LC (LC×LC) has attracted increasing attention in complex samples such as herb medicine, food additives, and so on for much higher peak capacity compared to 1D LC [12][13][14][15].…”

“…In light of this, comprehensive 2D reversed-phase × reversed-phase LC (RP × RP) system with different pH in mobile phase would be a better choice. Due to the dissociation characteristics of alkaloids, the separation mechanism of each dimension changes with the pH of the mobile phase, thereby improving the orthogonality [11,19]. Up to date, no work was reported to analysis of alkaloids in M. cordata (willd.)R.…”

Rapid Quantitative Detection of Deltamethrin in Corydalis yanhusuo by SERS Coupled with Multi-Walled Carbon Nanotubes

“…For example, the alkaloids in Corydalis ( Corydalis yanhusuo W.T. Wang) are one of the commonly used CHMs in traditional medical treatment as well as modern Western medical treatment for cancer, asthma, malaria, and other diseases [ 1 , 2 ]. However, the commercial cultivation of CHMs leads to the frequent application of diverse pesticides to prevent, repel or mitigate the effects of pests, which causes environmental pollution and threatens human health [ 3 , 4 ].…”