Fast determination of harmala alkaloids in edible algae by capillary electrophoresis mass spectrometry.
The use of algae as a foodstuff is rapidly expanding worldwide from the East Asian countries, where they are also used for medical care. Harmala alkaloids (HAlk) are a family of bioactive compounds found in the extracts of some plants, including wakame (Undaria pinnatifida), an edible marine invasive algae. HAlks are based on a characteristic β-carboline structure with at least one amino ionizable group. In this work, we report the successful separation of a mixture of six HAlks (harmine, harmaline, harmol, harmalol, harmane, and norharmane) by capillary electrophoresis ion-trap mass spectrometry (CE-IT-MS) in less than 8 min. Optimum separation in fused-silica capillaries and detection sensitivity in positive-ion mode were achieved using a background electrolyte (BGE) with 25 mmol L(-1) ammonium acetate (pH 7.8) and 10% (v/v) methanol, and a sheath liquid with 60:40 (v/v) isopropanol-water and 0.05% (v/v) formic acid. The separation method was validated in terms of linearity, limits of detection and quantification, repeatability, and reproducibility. Later, a sample pretreatment was carefully optimized to determine HAlks in commercial wakame samples with excellent recovery and repeatability. For the complex wakame extracts, the MS-MS fragmentation patterns of the different HAlks were useful to ensure a reliable identification. The complete procedure was validated using the standard-addition calibration method, determining matrix effects on the studied compounds. Harmalol, harmine, and harmaline were naturally present in the samples and were quantified at very low concentrations, ranging from 7 to 24 μg kg(-1) dry algae.
Laboratorio de Investigación y Desarrollo de Métodos Analíticos (LIDMA), Universidad Nacional de La Plata, Calle 47 y 115, 1900, La Plata, Buenos Aires, Argentina.
Marcos
M
Tascon
Fernando
F
Benavente
Victoria M
VM
Sanz-Nebot
Leonardo G
LG
Gagliardi
D019075:Electrophoresis, Capillary / Q000379:methods*; D005504:Food Analysis / Q000379:methods*; D006246:Harmaline / Q000032:analysis* / Q000737:chemistry; D006247:Harmine / Q000032:analysis* / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D044648:Undaria / Q000737:chemistry*
D006247:Harmine; D006246:Harmaline