title: Parts-per-trillion detection of harmala alkaloids in Undaria pinnatifida algae by on-line solid phase extraction capillary electrophoresis mass spectrometry.
abstract: β-carboline alkaloids of the harmala group (HAlks)-a family of compounds with pharmacologic effects-can be found at trace levels (<25 μg kg-1algae) in the edible invasive algae Undaria pinnatifida, known commonly as wakame. In this study, we present a simple and sensitive method to detect and quantify at low parts-per-trillion levels the six HAlks more frequently found in those plants. The method is based on on-line solid phase extraction capillary electrophoresis mass spectrometry using a C18sorbent. First, the methodology was optimized and validated with standard solutions through the use of ultraviolet (UV) and mass spectrometry (MS) detection. Second, the optimized method for MS detection was applied to an analysis of the HAlks in U. pinnatifida extracts. The method achieved limits of detection between 2 and 77 pg mL-1for standards, producing an analyte preconcentration of about 1000-times in comparison to CE-MS. Some matrix effects were observed for the complex wakame extracts, especially for the most polar HAlks (harmol and harmalol), which bear aromatic hydroxyl groups. Harmine, harmaline, and norharmane were not detected in the algal extracts, whereas harmane was found at 70 pg mL-1(70 ng kg-1dry algae). The results underscored that C18-SPE-CE-MS may be considered as a powerful method to detect trace levels of alkaloids and other bioactive small molecules in complex plant extracts.
authors.affiliation: Laboratorio de Investigación y Desarrollo de Métodos Analíticos (LIDMA), División Química Analítica, CONICET, Universidad Nacional de La Plata, Argentina.
authors.forename: Marcos
authors.initials: M
authors.lastname: Tascon
authors.affiliation: Laboratorio de Investigación y Desarrollo de Métodos Analíticos (LIDMA), División Química Analítica, CONICET, Universidad Nacional de La Plata, Argentina.
authors.forename: Leonardo G
authors.initials: LG
authors.lastname: Gagliardi
authors.affiliation: Departament d'Enginyeria Química i Química Analítica, Nutrition and Food Safety Research Institute (INSA-UB), Universitat de Barcelona, Barcelona, Spain. Electronic address: fbenavente@ub.edu.
authors.forename: Fernando
authors.initials: F
authors.lastname: Benavente
mesh_terms: D000470:Alkaloids / Q000032:analysis*; D019075:Electrophoresis, Capillary; D013058:Mass Spectrometry; D052616:Solid Phase Extraction; D044648:Undaria / Q000737:chemistry*
chemical_list: D000470:Alkaloids
keywords: Algae; Capillary electrophoresis; Harmala alkaloids; In-line or on-line preconcentration; Mass spectrometry