Study of flavonoids in aqueous spinach extract using positive electrospray ionisation tandem quadrupole mass spectrometry

• Published in: Food chemistry 2010-08, Vol.121 (3), p.863-870
• Main Authors: Dehkharghanian, Masood, Adenier, Hervé, Vijayalakshmi, Mookambeswaran A.
• Format: Article
• Language: English
• Subjects: Analytical chemistry; analytical methods; Apigenin; Biological and medical sciences; Chemical Sciences; CID-MS/MS; Electrospray ionisation; flavones; Flavonoids; flavonols; food analysis; food composition; Food engineering; Food industries; Fruit and vegetable industries; Fundamental and applied biological sciences. Psychology; HPLC; HPLC-ESI-MS/MS; ionization; Kaempferol; Life Sciences; luteolin; mass spectrometry; Multiple reaction monitory (MRM); myricetin; phytochemicals; plant extracts; polyphenols; Quercetin; Spinach; Spinacia oleracea; Tandem quadrupole mass spectrometry
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2010.01.007

The presence of three flavonols (quercetin, kaempferol, myricetin) and two flavones (apigenin, luteolin) were investigated in the extract of fresh spinach leaves. Aqueous spinach extracts were prepared with a leaf/water ratio of 1:2 at 80 °C for 30 min stirring. Ferric ammonium sulphate method was used for measuring total polyphenols in the extracts and expressed as catechins and tannic acid equivalents. The flavonoids glycosides in the extract were hydrolysed to their aglycons with 1.2 M HCl in boiling 50% water methanol solution. The resulting aglycons were identified and quantified by a C18 reverse phase high-performance liquid chromatography (RP-HPLC). Furthermore, the results were confirmed by HPLC coupled to an electrospray ionisation tandem triple-quadrupole mass spectrometer ESI-MS performing low-energy collision induced dissociation (CID-MS/MS) in the collision cell (HPLC-ESI-MS/MS). Analyses were made in the multiple reaction monitory (MRM) mode. Results showed that total polyphenols contents in fresh spinach leaves were 270 mg kg −1 and 390 mg kg −1 as tannic acid and catechin equivalents, respectively, in which, major flavonoids aglycons were apigenin (170 mg kg −1), quercetin (50 mg kg −1) and kaempferol (30 mg kg −1).