Signal enhancement of the laser-induced plasma in the soil mixed with carbon

An experimental investigation of the carbon concentration effects on the emission intensity has been carried out using laser-induced plasma spectroscopy. The results show that the intensity of Ca II 393.367 nm and 396.847 nm characteristic lines emitted in the sample with the carbon concentration of 25% is about five times larger than that in the pure soil sample. It can be attributed to the high heat transfer coefficient and low ionization potentials of carbon in the system. Using the best experimental condition, quantitative analysis of the trace element of lead is conducted and the detection limit of lead concentration is estimated to be below 0.02%.