title: Improved sample treatment for the determination of fructooligosaccharides in milk related products by liquid chromatography with electrochemical and refractive index detection.
abstract: A simple and reliable method for the determination of the fructooligosaccharides (FOS) kestose (GF2), nystose (GF3), fructofuranosylnystose (GF4), in the presence of fructose, glucose and lactose in dairy products is proposed. The most relevant advantages of the proposed method are the simultaneous determination of the most common FOS in enriched products and a reduction of the time required for sample treatment since the method consists merely in addition of a precipitation solution for the removal of lipids and proteins. Furthermore, the method saves a substantial amount of reagents compared with other methods and sample manipulation is reduced. Two chromatographic separations are proposed. The first one is carried out on an amino phase column for liquid chromatography with refractive index detection (HPLC-RI) (concentration of analytes higher than 0.1 mg mL(-1)) and the second one on an anion-exchange Carbopac PA-1 column for high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) (concentration of FOS lower than 0.1 mg mL(-1)). The method was validated by recovery assays with spiked samples using matrix-matched calibration. The limits of quantification of the method ranged from 1.2 to 2.0 µg mL(-1) for HPAEC-PAD and from 140 to 200 µg mL(-1) for HPLC-RI, while inter- and intra-day variability was under 3.5% in all cases. The proposed method was applied to the determination of compounds in supplemented milk, infant formulas and milk related juices with good recoveries in all cases.
authors.affiliation: Research Group of Analytical Chemistry and Life Sciences, Department of Analytical Chemistry, University of Granada, Campus of Fuentenueva, E-18071 Granada, Spain.
authors.forename: R
authors.initials: R
authors.lastname: Rodríguez-Gómez
authors.affiliation: Research Group of Analytical Chemistry and Life Sciences, Department of Analytical Chemistry, University of Granada, Campus of Fuentenueva, E-18071 Granada, Spain; Instituto de Investigación Biosanitaria ibs., Granada E-18012, Spain.
authors.forename: I
authors.initials: I
authors.lastname: Jiménez-Díaz
authors.affiliation: Research Group of Analytical Chemistry and Life Sciences, Department of Analytical Chemistry, University of Granada, Campus of Fuentenueva, E-18071 Granada, Spain. Electronic address: azafra@ugr.es.
authors.forename: A
authors.initials: A
authors.lastname: Zafra-Gómez
authors.affiliation: Department of Biochemistry and Pharmacology, Institute of Parasitology and Biomedicine "López Neyra", CSIC, Parque Tecnológico de Ciencias de la Salud, Avda. del Conocimiento, s/n.18016 Armilla, Granada, Spain.
authors.forename: J C
authors.initials: JC
authors.lastname: Morales
mesh_terms: D000818:Animals; D000837:Anion Exchange Resins; D002851:Chromatography, High Pressure Liquid; D002852:Chromatography, Ion Exchange; D005632:Fructose / Q000737:chemistry; D005947:Glucose / Q000737:chemistry; D041943:Infant Formula / Q000737:chemistry*; D007785:Lactose / Q000737:chemistry; D008892:Milk / Q000737:chemistry*; D009844:Oligosaccharides / Q000032:analysis* / Q000737:chemistry
chemical_list: D000837:Anion Exchange Resins; D009844:Oligosaccharides; C043600:fungitetraose; D005632:Fructose; D005947:Glucose; D007785:Lactose
keywords: Fructooligosaccharides; HPAEC-PAD; HPLC-RI; Milk related products