title: Determination of ochratoxin A in wheat after clean-up through a DNA aptamer-based solid phase extraction column.
abstract: A DNA aptamer with high affinity and specificity to ochratoxin A (OTA) was conjugated to a coupling gel and used as sorbent for the preparation of solid phase extraction (SPE) columns. The SPE columns packed with 300μl oligosorbent (24nmol DNA) showed a linear (r=0.999) behaviour in the range of 0.4-500ng OTA. After optimisation of the extraction step, SPE columns were used for clean-up of OTA from wheat prior to liquid chromatographic (HPLC) analysis with fluorescence detection (FLD). Average recoveries from wheat samples spiked at levels of 0.5-50ng/g ranged from 74% to 88% (relative standard deviation <6%) with limits of detection and of quantification of 23 and 77pg/g, respectively. The comparative HPLC/FLD analyses of 33 naturally contaminated durum wheat samples cleaned-up on both aptamer-SPE and immunoaffinity (IMA) columns showed a good correlation (r=0.990). Aptamer-SPE columns could be re-used up to five times without any loss of performance.
authors.affiliation: Institute of Sciences of Food Production, National Research Council, via Amendola 122/O, 70126 Bari, Italy. Electronic address: annalisa.degirolamo@ispa.cnr.it.
authors.forename: Annalisa
authors.initials: A
authors.lastname: De Girolamo
authors.affiliation: Department of Chemistry and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6.
authors.forename: Maureen
authors.initials: M
authors.lastname: McKeague
authors.affiliation: Department of Chemistry and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6.
authors.forename: J David
authors.initials: JD
authors.lastname: Miller
authors.affiliation: Department of Chemistry and Institute of Biochemistry, Carleton University, 1125 Colonel By Drive, Ottawa, ON, Canada K1S 5B6.
authors.forename: Maria C
authors.initials: MC
authors.lastname: DeRosa
authors.affiliation: Institute of Sciences of Food Production, National Research Council, via Amendola 122/O, 70126 Bari, Italy.
authors.forename: Angelo
authors.initials: A
authors.lastname: Visconti
keywords: DNA-aptamer; HPLC; Ochratoxin A; Oligosorbent; SPE columns; Wheat