Manganese is an essential element, but high levels in foods can be toxic mainly for children. A fast and efficient method to determine Mn in milk and other infant foods using slurries and liquid samples is presented. Slurries were prepared in ultrapure water with 10 minutes of sonication. Liquid samples were diluted in ultrapure water when necessary. Multivariate optimization was used to establish some optimal analytical parameters through a fractional factorial design and a central composite design. Slurred and diluted samples were analyzed directly by GF AAS. The method presented limit of detection of ( )？μg？L？1, characteristic mass of ( )？pg (recommended value 2？pg), RSD of 2.3% ( ), and linear range from 0.98 to 20.0？μg？L？1 using iridium as permanent modifier. The accuracy was evaluated analyzing two certified reference materials: nonfat milk powder (SRM1549) and whole milk powder (SRM8435). The powdered samples concentrations were between 0.210 and 26.3？μg？g？1. 1. Introduction Mn is an essential trace element that is present in all living cells. The human body in normal conditions contains about 10 to 20？mg of Mn, and it is present in numerous oxidoreductases and other enzymes exercising several biological functions [1, 2]. A daily ingestion of at least 3？mg is considered as necessary [2]. Although Mn is considered an essential element, the data are insufficient to settle down a value for the daily ingestion [3]. The fetal life and the first childhood are the most vulnerable periods to the Mn deficiency although rare [4]. This can cause dermatitis, problems in the glucose metabolism and of proteins, mitochondria abnormalities, infertilities, bad formation of the bones, decrease of the serum cholesterol, and others [5]. Although the Mn gastrointestinal absorption is only 3 to 5%, foods constitute the largest source of Mn in general for the population, and they are also the primary source of the absorbed metal [3]. The levels of daily alimentary ingestion estimated appropriate for 3–10-year-old age group is ranged of 1.0 to 2.0？mg day？1; over 10 years, it is ranged from 2.0 to 5.0 mg day？1; of 6 months to 1 year it is ranged of 0.6 to 1.0 mg day？1, and until 6 months, it is ranged from 0.3 to 0.6 mg day？1 [3]. Excess of Mn can be toxicant and the nervous system seems to be the most vulnerable [6]. The Mn neurotoxicity in adults is associated with symptoms of Parkinson disease while effects in children are not well characterized. Babies and children are quite sensitive to the Mn toxicity. Neonates accumulate more Mn than adults due to larger
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