Multi-elemental analysis of landfill leachates by single and double pulse laser-induced breakdown spectroscopy

In this work, the potential of single and double-pulse laser induced breakdown spectroscopy (SP and DP LIBS) has been investigated for multi-elemental analysis of the elements manganese, zinc, arsenic and lead in landfill leachates. Instrumental parameters such as detection delay and interpulse delay times were investigated in order to find the optimal operating values for multi-elemental analysis. The following emission lines were used: Mn II: 257.61; 259.37 and 260.56 nm; Zn II: 206.20 nm and Zn I: 213.85 nm; As I: 228.81; 234.98 nm and Pb I: 405.78 nm. All elements showed a strong enhancement factor (2.5) of DP LIBS signal intensities compared to SP LIBS. Analyses were performed using a background correction and the sum of the areas below each element emission lines. The limits of detection (LODs) achieved by SP LIBS were: 21.3, 77.5, 89.3, 38.9 mgkg-1 and for DP LIBS: 7.1, 13.4, 11.9 and 7.3 mgkg-1 respectively for Mn, Zn, As and Pb. The LOD values achieved by DP LIBS were improved by factors of 3, 6, 7.5 and 5 times respectively for Mn, Zn, As and Pb, with respect to SP LIBS. The average quantification errors were 7.5, 19.6, 38.2 and 28% for SP LIBS and 9.2, 21.3, 12.9 and 14.4% for DP LIBS respectively for Mn, Zn, As and Pb. The LIBS approach was demonstrated to be suitable for quantitative analysis of toxic elements and sufficiently fast for real time continuous monitoring of landfill leachates.