Determination of vitamin E in coffee beans by HPLC using a micro-extraction method

• Type: Article in International Scientific Journal
• Date: 2009

Authors

R C Alves (Author) FFUP; S Casal (Author) FFUP; MBPP Oliveira (Author) FFUP

Journal

Title: Food Science and Technology International

Vol. 15 No. 1

Pages: 57-63

ISSN: 1082-0132

Publisher: SAGE

Indexing

ISI Web of Knowledge - 35 Citations

ISI Web of Science

Scopus - 37 Citations

Scientific classification

FOS: Medical and Health sciences > Other medical sciences

CORDIS: Health sciences

Other information

Authenticus ID: P-003-NEN

Resumo (PT): This work reports a solid—liquid micro-extraction method for vitamin E quantification in coffee beans (before and after roasting) with normal-phase HPLC/diode-array/fluorescence detection. The compounds were extracted after protein precipitation and overnight maceration (4°C) in n-hexane, in the presence of butylated hydroxytoluene, using tocol as internal standard. The extraction method precision was inferior to 5% with mean recoveries near 100%. Chromatographic resolution from co-eluting interferences was achieved within 8 min with a 75 × 3.0 mm (3 μm) silica column by using an isocratic elution with n-hexane/ 1,4-dioxane (98 : 2), at a flow rate of 0.7 mL/min. The diode-array detector was a valuable tool in the detection of co-eluting interferences and quantification was based on the fluorescence measurements. Only two vitamers, a- and b-tocopherol, were confirmed and quantified, being the latter generally the major compound in both arabica and robusta coffees. The present analytical method proved to be simple, sensitive, reproducible, accurate, allowing a fast quantification with low organic solvent consumption <br> <br> Keywords: coffee beansvitamin Etocopherols HPLC <br> <br>

Abstract (EN): This work reports a solid—liquid micro-extraction method for vitamin E quantification in coffee beans (before and after roasting) with normal-phase HPLC/diode-array/fluorescence detection. The compounds were extracted after protein precipitation and overnight maceration (4°C) in n-hexane, in the presence of butylated hydroxytoluene, using tocol as internal standard. The extraction method precision was inferior to 5% with mean recoveries near 100%. Chromatographic resolution from co-eluting interferences was achieved within 8 min with a 75 × 3.0 mm (3 μm) silica column by using an isocratic elution with n-hexane/ 1,4-dioxane (98 : 2), at a flow rate of 0.7 mL/min. The diode-array detector was a valuable tool in the detection of co-eluting interferences and quantification was based on the fluorescence measurements. Only two vitamers, a- and b-tocopherol, were confirmed and quantified, being the latter generally the major compound in both arabica and robusta coffees. The present analytical method proved to be simple, sensitive, reproducible, accurate, allowing a fast quantification with low organic solvent consumption <br> <br> Keywords: coffee beansvitamin Etocopherols HPLC <br> <br>

Language: Portuguese

Type (Professor's evaluation): Scientific