The official procedures for determining vitamins are addressed to the individual analysis of each one, applying extracting conditions that permit exclusively the free form determination, among those ones present in a food, expression of the total vitamin content. The feasibility of using reversed-phase liquid chromatography/diode array/tandem mass spectrometry (LC-DAD-MS/MS) for the simultaneous analysis of five carotenoids (lutein, zeaxanthin, β-cryptoxanthin, β-carotene and lycopene) and nine compounds with fat-soluble vitamin activity (retinol and retinyl palmitate, α-tocopherol, δ-tocopherol, γ-tocopherol, ergocalciferol, cholecalciferol, phylloquinone and menaquinone-4) in bovine milk was evaluated. Analytes were separated on a C30 column and detected by an atmospheric pressure chemical ionization (APCI) source, operating in positive ion mode; a diode array detector was coupled on-line for identifying geometrical isomers of β-carotene and some unknown carotenoids occurring in bovine milk. Two procedures were tested for extracting concurrently the analytes: the overnight cold saponification, and the direct extraction with solvent. The first one resulted indispensable for recovering phylloquinone and carotenoids in particular and to preserve the isomerization of β-carotene all-trans and vitamin D, while the second one was employed to isolate retinyl esters. After cold alkaline hydrolysis, yields exceeding 77% were obtained for all analytes with the exception of zeaxanthin (62%), phylloquinone (6%) and menaquinone-4 (17%). The method precision was below 16%, and detection limit resulted less than 26 μg/L. The validated method was then applied to the characterization of vitamin and carotenoid profile of some milk samples (raw, pasteurized, biological, fermented). Direct extraction with hexane was also performed for calculating the individual contribution of retinol and retinyl palmitate to the total quantity of vitamin A and for identifying other retinyl esters by tandem MS screening techniques, since the corresponding standards are not commercially available.
Evaluation of a method based on LC-DAD-APCI-MS/MS for a rapid and comprehensive characterization of the fat-soluble vitamin and carotenoid profile of bovine milk / Bellante, Simona; Gentili, Alessandra; Caretti, Fulvia; G., D’Ascenzo; Curini, Roberta. - STAMPA. - (2010). (Intervento presentato al convegno XXII Congresso della Divisione di Chimica Analitica tenutosi a Como, Italy nel 13-16 Settembre 2010).
Evaluation of a method based on LC-DAD-APCI-MS/MS for a rapid and comprehensive characterization of the fat-soluble vitamin and carotenoid profile of bovine milk
BELLANTE, SIMONA;GENTILI, Alessandra;CARETTI, Fulvia;CURINI, Roberta
2010
Abstract
The official procedures for determining vitamins are addressed to the individual analysis of each one, applying extracting conditions that permit exclusively the free form determination, among those ones present in a food, expression of the total vitamin content. The feasibility of using reversed-phase liquid chromatography/diode array/tandem mass spectrometry (LC-DAD-MS/MS) for the simultaneous analysis of five carotenoids (lutein, zeaxanthin, β-cryptoxanthin, β-carotene and lycopene) and nine compounds with fat-soluble vitamin activity (retinol and retinyl palmitate, α-tocopherol, δ-tocopherol, γ-tocopherol, ergocalciferol, cholecalciferol, phylloquinone and menaquinone-4) in bovine milk was evaluated. Analytes were separated on a C30 column and detected by an atmospheric pressure chemical ionization (APCI) source, operating in positive ion mode; a diode array detector was coupled on-line for identifying geometrical isomers of β-carotene and some unknown carotenoids occurring in bovine milk. Two procedures were tested for extracting concurrently the analytes: the overnight cold saponification, and the direct extraction with solvent. The first one resulted indispensable for recovering phylloquinone and carotenoids in particular and to preserve the isomerization of β-carotene all-trans and vitamin D, while the second one was employed to isolate retinyl esters. After cold alkaline hydrolysis, yields exceeding 77% were obtained for all analytes with the exception of zeaxanthin (62%), phylloquinone (6%) and menaquinone-4 (17%). The method precision was below 16%, and detection limit resulted less than 26 μg/L. The validated method was then applied to the characterization of vitamin and carotenoid profile of some milk samples (raw, pasteurized, biological, fermented). Direct extraction with hexane was also performed for calculating the individual contribution of retinol and retinyl palmitate to the total quantity of vitamin A and for identifying other retinyl esters by tandem MS screening techniques, since the corresponding standards are not commercially available.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
