title: Determination of egg yolk xanthophylls by isocratic high-performance liquid chromatography.
abstract: An isocratic HPLC method was developed for the determination of eight xanthophylls (lutein, capsanthin, zeaxanthin, canthaxanthin, β-apo-8'-carotenal, ethyl-8'-apo-β-carotene-8'-oate, citranaxanthin and β-cryptoxanthin; registered as additives in poultry feeding) in egg yolks. Optimum separation of all-E-isomers of these xanthophylls was achieved in less than 18min on a ProntoSIL C30 column at 27°C using acetone-methanol-0.5M triethylammonium acetate buffer pH 7 14:5:1 (v/v) as the mobile phase with a flow rate of 1mL/min using spectrophotometric detection at 450nm. Other mobile phases were also found suitable, including acetone-water 93:7 (v/v) and acetone-methanol 1:4 (v/v) and the influences of column temperature on the separation and addition of triethylammonium acetate buffer pH 7 to the mobile phase on enhancement of the peak areas were evaluated. Preparation of test solution from yolks included a short vortexing of 0.5g of yolk in 10mL of acetone, followed by 15min magnetic stirring under nitrogen and centrifugation. The method was validated for 5 analytes. The calibration range was between 0.04 and 2μg/mL and the mean recovery of the analytes (95%) and the intra-day precision of the method (RSD less than 5%) on three levels in triplicates were obtained. Analyses of eggs from four husbandry classes showed the presence of up to four xanthophylls (lutein, zeaxanthin, canthaxanthin and ethyl-8'-apo-β-carotene-8'-oate) and traces of β-cryptoxanthin.
authors.affiliation: National Institute of Chemistry, Laboratory for Food Chemistry, Hajdrihova 19, SI-1000 Ljubljana, Slovenia.
authors.forename: Lučka
authors.initials: L
authors.lastname: Brulc
authors.forename: Breda
authors.initials: B
authors.lastname: Simonovska
authors.forename: Irena
authors.initials: I
authors.lastname: Vovk
authors.forename: Vesna
authors.initials: V
authors.lastname: Glavnik
mesh_terms: D000818:Animals; D002645:Chickens; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004530:Egg Yolk / Q000737:chemistry*; D024341:Xanthophylls / Q000032:analysis*
chemical_list: D024341:Xanthophylls
keywords: C30 column; Egg yolk; HPLC; Triethylammonium acetate; Xanthophylls