Determination of colloidal iron in water by laser-induced breakdown spectroscopy

Laser-induced breakdown spectroscopy was applied to the determination of FeO(OH) in water and successfully determined the concentration of the turbid solution down to a few ppm (μg ml−1). A Q-switched Nd:YAG laser, which delivered 8 ns pulses, was used as an excitation source. Cell-less measurement was achieved using a coaxial nozzle flow system which allowed to study the effect of ambient gas on emission intensity and decay lifetime of the breakdown plasma. Using helium gas and with a proper timing gate, the FeO(OH) concentration in water was determined in the ppm range.