“…It has a relatively high preconcentration factor and the ability of treating large volume samples free from contamination [14][15][16]. Various solid-phase materials including Ambersorb resins, Chromosorb resins, Diaion resins, naphthalene, silica gel, activated carbon, chelating resins and fibers [17][18][19][20][21][22][23][24] have been used up to now.…”