SI-based dynamic flow-through fractionation is a novel technique for assessing the bioavailability, and potentially toxic metal ions (Cu, Pb, Zn), in soil samples. (Chomchoei et al. 2005, Miró and Hansen 2006).

Initially designed as a complementary approach to equilibrium-based, batch-based fractionation schemes,  additional data obtained with standard soil samples confirmed  that the SI on-line technique provides comparable results with the batch technique, yet  offers a better resolution during the initial stages of leaching (A) than the slower fraction collection-based batch technique.

The SI method is fully automated, and the leaching and monitoring takes place in a closed system, protected from external contamination. The apparatus is based on the conventional SI instrument with an additional peristaltic pump and external valve. The heart of the system is a specially constructed low flow resistance column. The technique was further refined to allow study of
leaching of Cr (Long, Miró and Hansen 2006).

Bioavailability of Metals in Soils
M. Miró, E.H. Hansen Trends in Analytical Chemistry, Vol. 25, No. 3, 2006
R. Chomchoei, M. Miro´ , E.H. Hansen, J. Shiowatana, Anal. Chim. Acta 536 (2005) 183
R. Chomchoei, M. Miro´ , E.H. Hansen, J. Shiowatana, Anal. Chem.77 (2005) 2720
X.B.Long, M.Miró and E.H.Hansen Analyst 131 , 132, 2006