Analysis of microsamples by miniaturized magnetic-based pipette tip microextraction: determination of free cortisol in serum and urine from very low birth weight preterm newborns

1. Grau, J.
2. Moreno-Guzmán, M.
3. Arruza, L.
4. López, M.I.
5. Escarpa, A.
6. Chisvert, A.