Ultra-trace elemental and isotopic quantification for neonatal nutrition studies

Little is known about the presence and function of trace and ultra-trace elements in pre-term infants whose birth weight is 500-2000 g. Resonance ionization spectroscopy (RIS) is being used to solve these problems. RIS utilizes a source of tunable laser radiation that is resonant with a specific atomic energy level. In the simplest two photon RIS scheme a second photon of the same energy promotes the excited electron to the ionization continuum, forming an atomic ion. This simple two photon process can be used to ionize approximately fifty elements, but a series of RIS schemes has been proposed by G.S. Hurst et al., to ionize all elements except He and Ne. Resonance ionization advantages are three-fold: 1) sensitivity, 2) selectivity, and 3) generality. The experimental design was structured toward the longer term research goal: to provide for the neonatologist a total multi-elemental and isotopic diagnostic analysis using only a few microliters of blood.