title: Total zinc quantification by inductively coupled plasma-mass spectrometry and its speciation by size exclusion chromatography-inductively coupled plasma-mass spectrometry in human milk and commercial formulas: Importance in infant nutrition.
abstract: This paper summarises results of zinc content and its speciation in human milk from mothers of preterm and full-term infants at different stages of lactation and from synthetic formula milks. Human milk samples (colostrum, 7th, 14th, and 28th day after delivery) from Spanish and Brazilian mothers of preterm and full-term infants (and also formula milks) were collected. After adequate treatment of the sample, total Zn was determined, while speciation analysis of the Zn was accomplished by size exclusion chromatography coupled online with the ICP-MS. It is observed that total zinc content in human milk decreases continuously during the first month of lactation, both for preterm and full term gestations. All infant formulas analysed for total Zn were within the currently legislated levels. For Zn speciation analysis, there were no differences between preterm and full term human milk samples. Moreover Zn species elute mainly associated with immunoglobulins and citrate in human milk whey. Interestingly the speciation in formula milk whey turned out to be completely different as the observed Zn(2+) was bound almost exclusively to low molecular weight ligands (citrate) and only comparatively very low amounts of the metal appeared to be associated with higher mass biomolecules (e.g. proteins).
authors.affiliation: Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Oviedo, Spain.
authors.forename: Sonia
authors.initials: S
authors.lastname: Fernández-Menéndez
authors.affiliation: Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Oviedo, Spain. Electronic address: marisafs@uniovi.es.
authors.forename: María L
authors.initials: ML
authors.lastname: Fernández-Sánchez
authors.affiliation: Service of Neonatology, Department of Pediatrics, Hospital Universitario Central de Asturias, Oviedo, Spain.
authors.forename: Belén
authors.initials: B
authors.lastname: Fernández-Colomer
authors.affiliation: Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Oviedo, Spain.
authors.forename: Rafael R
authors.initials: RR
authors.lastname: de la Flor St Remy
authors.affiliation: Service of Neonatology, Department of Pediatrics, Hospital Universitario Central de Asturias, Oviedo, Spain.
authors.forename: Gil Daniel Coto
authors.initials: GD
authors.lastname: Cotallo
authors.affiliation: Department of Analytical Chemistry, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: Aline Soares
authors.initials: AS
authors.lastname: Freire
authors.affiliation: Department of Analytical Chemistry, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: Bernardo Ferreira
authors.initials: BF
authors.lastname: Braz
authors.affiliation: Department of Analytical Chemistry, Universidade Federal do Rio de Janeiro, Brazil.
authors.forename: Ricardo Erthal
authors.initials: RE
authors.lastname: Santelli
authors.affiliation: Department of Physical and Analytical Chemistry, Faculty of Chemistry, University of Oviedo, Oviedo, Spain. Electronic address: asm@uniovi.es.
authors.forename: Alfredo
authors.initials: A
authors.lastname: Sanz-Medel
mesh_terms: D001938:Brazil; D002850:Chromatography, Gel; D002951:Citrates / Q000737:chemistry; D005504:Food Analysis / Q000379:methods*; D006801:Humans; D007223:Infant; D041943:Infant Formula / Q000737:chemistry*; D013058:Mass Spectrometry; D008895:Milk, Human / Q000737:chemistry*; D008970:Molecular Weight; D015032:Zinc / Q000032:analysis*
chemical_list: D002951:Citrates; D015032:Zinc
keywords: Chromatography coupled to mass spectrometry; Dietary supplements; Preterm and full term milk; Speciation; Zinc levels and deficiency