LC-MS analysis of alkamides in Echinacea purpurea and Echinacea pallida cultivated in Turkey

Root extracts of the Echinacea purpurea (L.) Moench and E. pallida (Nutt.) Nutt. are widely used for medicinal purposes. Effective quality control of these extracts requires rapid methods to determine their chemical composition [1]. E purpurea and E. pallida were cultivated in the experimental farm of Selcuk University, Faculty of Agriculture in ecological conditions of Konya. Echinacea purpurea and E. pallida contain caffeic acid derivatives and alkamides. They are known as immunstimulant plants. Their specifications and some analysis methods have been described in the monographs of the European Pharmacopea [2]. Liquid chromatography is a fundamental separation technique in the life sciences and related fields of chemistry. Mass spectrometers also generate three dimensional data. In addition to signal strength, they generate mass spectral data that can provide valuable information about the molecular weight, structure, identity, quantity, and purity of a sample. We used an HPLC/electrospray ionization mass spectrometry method for simultaneous analysis of alkamides in the root extracts of Echinacea purpurea and Echinacea pallida cultivated in Turkey. The analysis was carried out with reversed phase HPLC coupled to electrospray ionization mass spectrometry (ESI-MS). The mass spectra were taken on a Waters ZQ micromass LC-MS spectrometer (Waters Corporation, Milford, MA, USA) by using ESI(+) method. The mass spectrometer was operated with a scan range of 90–900 m/z, a capillary temperature of 200°C, a maximum column pressure of 300bar. Voltages of capillary, cone, extractor and RF lens are 3.6kV, 24 V, 2 V, 0.1 V. İt was tuned in the positive ion mode. Total analysis time was 20 minutes. Alkamides (undeca-2Z,4E-diene-8,10-dynoic acid isobutylamide, undeca-2E,4Z-diene-8,10-dynoic acid 2-methylbutylamide, dodeca-2E,4E,8Z,10Z-tetraenoic acidisobutylamide) were separated and determined using a xterra MS C18 (4.6×250mm; 5µm) column by isocratic elution with flow rate 0.5ml/min. The mobile phase composition was methanol- Acetonitrile- 0.1% TFA in water (55:35:10) (v/v/v).

References: [1] Cech, N. B. et al. (2006) J. Chromatogr. 1103 (2): 219–228 [2] European Pharmacopoeia (2005), 5th edition, Council of Europe, Strasbourg.