Quantification of Inorganic Constituents in Brazilian Human Milk by ICP OES

Abstract

A fast procedure to determine essential and toxic metals in Brazilian human milk by ICP OES is proposed. Mature and colostrum human milk samples were mineralized using closed-pressurized and high-performance microwave digestion oven. Aqueous calibration was performed for all analytes investigated. A reference material, Infant Formula, was analyzed to test the accuracy of the proposed methodology. Recovery rates ranged between 83 and 117%. The precision of the method was better than 3.3% (R.S.D.) for all analytes investigated. Higher concentrations, on average, of the metals studied in the colostrum human milk could be found in relation to the mature human milk.

Keywords:

• Human milk
• ICP OES
• Microwave digestion

The authors are thankful to Conselho Nacional de Pesquisa e Desenvolvimento Tecnológico (CNPq), Fundação de Amparo à Pesquisa do Estado de Minas Gerais (FAPEMIG), and Maternidade Odete Valadares. R.S. Nascimento has scholarships from CNPq. J.B.B. Silva is grateful to CNPq for the research grants.

Notes

I = Atomic line; II = Ionic line.

^a LOD and LOQ in mg L⁻¹ to Ca, Na, Mg and K; and to the others analytes in µg L⁻¹.

^a LOQ in mg L⁻¹ to Ca, Na, Mg and K; and to the others analytes in µg L⁻¹.

^b Calculated on 10 independents samples at the following concentrations: 10.0 µg L⁻¹to Li, Ba, V, Cr, Ni, Mn, Pb, Cu, Co, Cd, and Al; 15.0 µg L⁻¹ to Fe and Zn, 200.0 mg L⁻¹ to Ca, 300.0 mg L⁻¹ to K and 30.0 mg L⁻¹ to Mg and Na.

^c Performed on the NIST SRM 1846 Infant Formula.

^d Mean ± S.D.

^e nc: not certified and ic: informed concentration.

^f t _{95%, 2} = 4,303.

Level 1: 50.0 mg L⁻¹ to Ca; 75.0 mg L⁻¹ to K; 20.0 mg L⁻¹ to Mg and Na; and 5.0 µg L⁻¹ to the others metals.

Level 2: 200.0 mg L⁻¹ to Ca; 300.0 mg L⁻¹ to K; 40.0 mg L⁻¹ to Mg and Na; and 20.0 µg L⁻¹ to the others metals.

Level 3: 400.0 mg L⁻¹ to Ca; 600.0 mg L⁻¹ to K; 60.0 mg L⁻¹ to Mg and Na; and 40.0 µg L⁻¹ to the others metals.

^a Concentration in mg L⁻¹ to Ca, Na, Mg and K, and in µg L⁻¹, to the others analytes.

^b Value with exception of 6 samples which has values less than LOQ.

^c Value with exception of 7 samples which has values less than LOQ.

^d Value with exception of 5 samples which has values less than LOQ.

^e Value with exception of 12 samples which has values less than LOQ.