Determination of peimine and peiminine in Bulbus Fritillariae Thunbergii by capillary electrophoresis by indirect UV detection using N‐(1‐naphthyl)ethylenediamine dihydrochloride as probe

Abstract

A simple and inexpensive CE method was developed for the determination of peimine and peiminine. Because of the lack of an UV chromophore of peimine and peiminine, the detection method chosen was indirect UV detection, with N-(1-naphthyl)ethylenediamine dihydrochloride (NED) as the UV absorbing probe. It was thought that NED, a chromophoric ion, may form hydrogen bonding pairs with the analytes to cause significant changes in separation selectivity. Additionally, the hydrophobic interactions between analytes and the probe also play a crucial role in achieving a resolution between the two analytes. The analyses were carried out with a background electrolyte composed of 66% MeOH-ACN (1:1, v/v), 34% aqueous buffer containing 15 mM NaH₂PO₄, 2.5 mM NED, 4 mM H₃PO₄. MeOH-ACN mixtures used as organic modifiers can not only reduce the adsorption of NED to the capillary wall, but also decrease the baseline noise and drift. The method provided a linear response ranging from 5 to 200 μg/mL. The limits of detection (LODs) for peimine and peiminine were 3.9 and 4.1 μg/mL, respectively. The repeatabilities (n = 3) reached relative standard deviation values (RSDs) of 3.4 and 4.1% for the peak areas, 4.0 and 4.4% for the peak heights, and 0.29 and 0.30% for the migration time of peimine and peiminine, respectively. Regression equations revealed linear relationships (r = 0.9995-0.9996) between the peak area of each analyte and the concentration. The method developed was successfully applied to quantify peimine and peiminine in chloroform extracts of the ground Bulbus Fritillariae Thunbergii.

Advance of CE and CEC in phytochemical analysis (2012–2013)

“…Methanol, ethanol, or their aqueous solutions, and water were usually employed for the extraction, though acetone , ethyl acetate , chloroform , and 3% sulfuric acid were also sometimes used (Tables and ).…”

“…Neutral molecules such as saccharides could also be analyzed by CZE, and an extremely high pH (sodium hydroxide used as running buffer) was employed . In order to increase the solubility of less polar compounds and improve the selectivity, organic solvents are usually used as additives in CE analysis . Especially, NACE, using organic solvents instead of water, was used in CZE.…”

“…UV detector is the standard detection of commercial CE system, though the concentration sensitivity is low due to its shorter optical path length. Both direct (with or without derivatization) and indirect (by adding substance with strong UV absorption into BGE) UV detections were used for phytochemical analysis. For derivatization, 1‐phenyl‐3‐methyl‐5‐pyrazolone and 4‐aminobenzoic acid ethyl ester were used as derivative agents for CE analysis carbohydrates.…”

“…For derivatization, 1‐phenyl‐3‐methyl‐5‐pyrazolone and 4‐aminobenzoic acid ethyl ester were used as derivative agents for CE analysis carbohydrates. While N ‐(1‐naphthyl)ethylenediamine dihydrochloride and phthalic acid were employed as probe for analysis of peimine and peiminine in Bulbus Fritillariae Thunbergii and organic aliphatic acids in extracts of Brachiaria brizantha , respectively. A promising CE method with direct UV detection was proposed for analysis of neutral carbohydrates under extremely high alkaline conditions .…”

Effects of ion pairing on the capillary electrophoretic separation and ultraviolet‐absorption detection of quaternary ammonium cations using meso‐octamethylcalix[4]pyrrole as the background electrolyte additive

“…Typically, this method relies on particular chromophores or fluorophores especially, which is a requirement of spectroscopically based detection methods. Because many cations do not have significant UV absorbance, indirect on‐column detection is generally applied, and imidazoles or UV‐absorbing organic amines are frequently used as a probe compound . Because the sensitivity of this technique significantly relies on the probe compound, selecting appropriate chromophoric ions is a challenge that limits the application of this method.…”