Assessment of the content of selected trace elements in serum of term and pre-term newborns by inductively coupled plasma mass spectrometry

A method for the determination of 14 trace and ultra-trace elements (Al, Cd, Co, Cu, Li, Mn, Mo, Ni, Pb, Pt, Rb, Sb, Se and Zn) in serum of newborns by inductively coupled plasma mass spectrometry (ICP-MS) with ultrasonic nebulization is described. Cord blood samples were collected from term and pre-term newborns by means of a teflon catheter within 24 h from delivery. The eligibility criteria adopted in this study require that only “normal” (i.e. fully representative of their specific conditions) subjects be selected for blood collection. From this standpoint, pre-term newborns suffering only from diseases derived from their status, i.e. really representative of the group under investigation, were included in the study. After centrifugation, serum aliquots were stored in metal-free plastic test tubes at −20 °C until analysis. Sample treatment was kept to a minimum, i.e. serum samples were diluted 20–50-fold with 0.14 M HNO3 and spiked with suitable amounts of Rh and Tl, the internal standards, to account for nebulization effects and for instability of nebulization and ionization. To minimize the effects of matrix interferences, blanks and calibrants were prepared from synthetic solution containing the same major components as the real sample solutions. The analytical method adopted, i.e. ICP-MS determination combined with ultrasonic nebulization, turned out to be fully suited to the aim of this study. Experimental data were statistically analyzed by parametric and non-parametric tests in order to assess tentative reference ranges of elemental concentrations. To this end, newborns were grouped by gestational age and body weight at the delivery. Results allow tentative reference values to be assessed for the above-mentioned elements in serum of newborns, with the only exception of Pt, which was below the detection power of the technique.