Development, validation and evaluation of an analytical method for the determination of monomeric and oligomeric procyanidins in apple extracts.
There is a lack of data for individual oligomeric procyanidins in apples and apple extracts. Our aim was to develop, validate and evaluate an analytical method for the separation, identification and quantification of monomeric and oligomeric flavanols in apple extracts. To achieve this, we prepared two types of flavanol extracts from freeze-dried apples; one was an epicatechin-rich extract containing ∼30% (w/w) monomeric (-)-epicatechin which also contained oligomeric procyanidins (Extract A), the second was an oligomeric procyanidin-rich extract depleted of epicatechin (Extract B). The parameters considered for method optimisation were HPLC columns and conditions, sample heating, mass of extract and dilution volumes. The performance characteristics considered for method validation included standard linearity, method sensitivity, precision and trueness. Eight laboratories participated in the method evaluation. Chromatographic separation of the analytes was best achieved utilizing a Hilic column with a binary mobile phase consisting of acidic acetonitrile and acidic aqueous methanol. The final method showed linearity for epicatechin in the range 5-100μg/mL with a correlation co-efficient >0.999. Intra-day and inter-day precision of the analytes ranged from 2 to 6% and 2 to 13% respectively. Up to dp3, trueness of the method was >95% but decreased with increasing dp. Within laboratory precision showed RSD values <5 and 10% for monomers and oligomers, respectively. Between laboratory precision was 4 and 15% (Extract A) and 7 and 30% (Extract B) for monomers and oligomers, respectively. An analytical method for the separation, identification and quantification of procyanidins in an apple extract was developed, validated and assessed. The results of the inter-laboratory evaluation indicate that the method is reliable and reproducible.
Institute of Food Research, Norwich Research Park, Norwich, UK. Electronic address: authorspaul.kroon@ifr.ac.uk.
Wendy J
WJ
Hollands
VITONV, Flemish Institute for Technological Research, Boeretang 200, 2400 Mol, Belgium.
Stefan
S
Voorspoels
VITONV, Flemish Institute for Technological Research, Boeretang 200, 2400 Mol, Belgium.
Griet
G
Jacobs
Nofima, Norwegian Institute of Food, Fisheries and Aquaculture Research, Ås, Norway.
Kjersti
K
Aaby
Nofima, Norwegian Institute of Food, Fisheries and Aquaculture Research, Ås, Norway.
Ane
A
Meisland
Research Group on Quality, Safety and Bioactivity of Plant Foods, CEBAS-CSIC, Campus de Espinardo, Murcia, Spain.
Rocio
R
Garcia-Villalba
Research Group on Quality, Safety and Bioactivity of Plant Foods, CEBAS-CSIC, Campus de Espinardo, Murcia, Spain.
Francisco
F
Tomas-Barberan
Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, Olsztyn, Poland.
Mariusz K
MK
Piskula
LGC, Fordham, Cambridge, UK.
Deborah
D
Mawson
National Institute of Chemistry, Ljubljana, Slovenia.
Irena
I
Vovk
Institute of Food Research, Norwich Research Park, Norwich, UK.
Paul W
PW
Needs
Institute of Food Research, Norwich Research Park, Norwich, UK.
Paul A
PA
Kroon
D044946:Biflavonoids / Q000032:analysis* / Q000302:isolation & purification; D002392:Catechin / Q000032:analysis* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D005612:Freeze Drying; D057230:Limit of Detection; D027845:Malus / Q000737:chemistry* / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry*; D044945:Proanthocyanidins / Q000032:analysis* / Q000302:isolation & purification; D013237:Stereoisomerism; D013696:Temperature
D044946:Biflavonoids; D010936:Plant Extracts; D044945:Proanthocyanidins; C017674:procyanidin; D002392:Catechin
Flavanols flavan-3-ols; HPLC; Inter-laboratory evaluation; Phenolics; Polyphenols; Tannins