FAAS and k/sub 0/-INAA analysis protocols for the determination of essential and toxic metals in fresh and packed milk samples

This study assesses the intake adequacy of elements determined in fresh, ultra high temperature (UHT) treated and powder milk samples. The samples were analyzed for fourteen elements (Br, Ca, Cl, Cs, Cu, Fe, K, Mg, Na, P, Rb, Sn, Sr and Zn) by semi-absolute k/sub 0/ instrumental neutron activation analysis (INAA), epithermal neutron activation analysis (ENAA) and flame atomic absorption spectrophotometry (AAS) with proper method validation. NAA and AAS methodologies were validated by analyzing three reference materials. The results of 10 elements (Br, Co, Cr, Cs, Fe, K, Na, Rb, Sc and Zn) determined in IAEA-336 by k/sub 0/-INAA, iodine in NIST-SRM-1572 (citrus leaves) by ENAA and 4 elements (Cd, Cu, Ni and Pb) by AAS are presented with 95% confidence intervals. The daily intakes were compared with the dietary reference intakes (DRIs) defined for male of age group 31-50 years. This comparison reveals that fresh milk is best in providing most of the essential elements (Ca, I, P, Zn, Mg). UHT treated and powder samples are slightly better in Cu and Fe. It can be said that fresh milk is good source of Ca, I, P and Zn but poor source of Fe. The daily intake of lead, identified in only two samples, was compared with the provisional tolerable weekly intake (PTWI) defined by Food and Agriculture Organization (FAO) and World Health Organization (WHO), which is 25 mu g/(kg body weight). Lead was evaluated for a person drinking 250 ml of milk/day and weighing 70 kg. It produced weekly intake of 3.1 mu g, a value well below the PTWI. (Orig./A.B.)