Laser induced breakdown spectroscopy (LIBS) as an analytical tool for the detection of metal ions in aqueous solutions

Laser induced breakdown spectroscopy (LIBS) is applied to analyze aqueous solutions of Li+, Na+, Ca2+, Ba2+, Pb2+, Cd2+, Hg2+ and Er3+ and suspensions of ErBa2Cu3O particles (d = 0.2 mu m). An excimer (308 nm) pumped dye laser with laser pulse at 500 nm and pulse energy at 22 +/- 2 mJ is used to produce plasma in aqueous solution. Plasma emission lines of the elements are detected by a photodiode array detector. Detection limits of the metal ions are 500 mg/l for Cd2+, 12.5 mg/l for Pb2+, 6.8 mg/l for Ba2+, 0.13 mg/l for Ca2+, 13 mu g/l for Li+ and 7.5 mu g/l for Na+. No mercury and erbium emission can be detected, even at Hg2+ and Er3+ concentrations of up to the g/l range. On the other side, for Er in suspensions of ErBa2Cu3Ox particles a more than 10(3) times higher sensitivity is found than for dissolved Er3+. This result gives a possibility to analyze colloid-borne metal ions with an increased sensitivity.