Copper fractionation by SEC-HPLC and ETAAS: Study of breast milk and infant formulae whey used in lactation of full-term newborn infants

Abstract

This method will allow the determination of bound copper to low relative molecular mass compounds in milk. The milk whey obtained by ultracentrifugation was submitted to fractionation by size exclusion chromatography (SEC) on a TSK-Gel2000 (Toso Haas) column with a mobile phase of 0.2 M NH4NO3 + NH3, pH 6.7. Fractions of effluent corresponding to the protein peaks were collected and the copper content was determined by ETAAS. The method was sensitive (LOD 0.4 microgram l-1 and LOQ 1.5 micrograms l-1 in the fraction; LOQ 7.5-22.5 micrograms l-1 referred to the milk sample and depended on fraction volume) and precise (RSD +/- 10%). Media sample recoveries from the column were 101.2%. Cu was predominantly present in fractions corresponding to relative molecular mass 76 and 15 kDa of breast milk while copper was mostly found in fractions corresponding to 14 and 38 kDa of cow's milk-based infant formulae; moreover, copper was eluted in the relative molecular mass region < 6 kDa.

Determination of As, Cd, Cu, Hg and Pb in biological samples by modern electrothermal atomic absorption spectrometry

“…In this sense, chromatography is a powerful tool for speciation [119][120][121] and can be applied off line [122] or incorporated on line in automated FIA systems and, with an autosampler, be directly injected into the atomizer. The processes most commonly implemented on line with FIA systems are pre-concentration by liquid-solid extraction (LSE) [36,47,91,119], liquid-liquid extraction (LLE) [124][125][126][127][128], or coprecipitation [108,109], separation of different analytes [47] and chemical vapor generation [35,37,43,62,71,100,129].…”

Speciation of Zinc

“…However, in infant formula milk whey, zinc was detected only in the fractions with molecular masses of smaller than 5,000 Da and of greater than 158,000 Da. These differences in zinc distribution can be important for the bioavailability [70]. …”

A importância da análise de especiação do chumbo em plasma para a avaliação dos riscos à saúde

“…Favarato e colaboradores identificaram um novo carreador de alumínio no soro humano, através da cromatografia por exclusão de tamanho de alta resolução e posterior determinação do metal por ET AAS 93 . Este mesmo acoplamento também permitiu a análise de especiação de Pb e Pt em amostras biológicas 94 , de Cu em leite humano 95 e As nas células vermelhas do sangue 96 . Uma técnica híbrida entre HPLC e ET AAS foi desenvolvida para estudar a ligação de proteínas com Al e Fe 97 e determinar as espécies de Pt no plasma 98 .…”

“…Os complexos de magnésio com proteí-nas do soro humano foram separados por meio de uma coluna de troca iônica e o metal quantificado por ET AAS 101 . A cromatografia por exclusão de tamanho e a espectrometria de absorção atômica na chama foram usadas para a determinação das espécies metálicas existentes no soro do leite 102 . A hifenização da cromatografia líquida de alta resolução com a espectrometria de absorção atômica por geração de hidretos (HG AAS) permitiu a análise de especiação de arsênio na urina 103 .…”