Analysis of phenolic compounds in onion nectar by miniaturized off-line solid phase extraction-capillary zone electrophoresis

SOTO VERÓNICA C; FERNÁNDEZ MARÍA DE LOS ANGELES; GALMARINI CLAUDIO; SILVA MARIA FERNANDA

Analytical Methods

RSC Publishing

Lugar: Cambridge; Año: 2014 vol. 6 p. 4878 - 4884

1759-9660

Onion is an important vegetable crop which depends heavily on cross-pollinating insects for any significantincrease in seed production. Nectar is the most important floral reward offered by plants. Minorcomponents such as phenolic compounds in nectar affect bee foraging. A simultaneous determinationof 4-vinylphenol, catechin, naringenin, rutin, cinnamic acid, syringic acid, chlorogenic acid, apigenin,vanillic acid, luteolin, quercetin, and caffeic acid in onion nectar lines by CZE-UV is reported. Limitednectar amounts make it difficult to apply the most commonly employed methods of extraction forphenolic compounds. Thus, the extraction of phenolic compounds in nectar was performed by solidphase extraction (SPE) using a home-made minicolumn packed with a suitable filtering material (C18,50 mg) connected to a vacuum pump. Effects of several important factors affecting extraction efficiencyas well as electrophoretic performance were investigated to acquire the optimum conditions. Under theproposed conditions, the analytes could be separated within 8 min in a 50 cm effective length capillary(75 mm ID) at a separation voltage of 25 kV in 30 mmol L1 boric acid as BGE (pH 9.5). Sample resultssuggest that the phenolic composition has great influence on bee preference. Furthermore, themarkedly qualitative and quantitative analytical differences in the phenolic profile of onion lines found inthis study contribute to the understanding of the factors that affect onion pollination for hybrid seedproduction.