International audienceThis work is dedicated to a comparison of plasma conditions for the accurate determination of some elements: Br, Cl, Ca, P and Sb, in polymers. The comparison of the plasma conditions to sort plastics according to CN, C2 and element signals was also investigated. The comparison of a helium atmosphere and an air atmosphere led to improved results using helium as a buffer gas. The improvement is obtained in two areas, it increased the detection of halogens (Br, Cl) usually employed as flame retardants. It was also found to significantly improve the discrimination based on simple calculations of C2/He and CN/He ratios. Best conditions were based on a laser emitting at 266 nm, with a low 6 mJ energy focalized on a 50 μm spot and the helium buffer gas. A plot of C2/He against CN/He was efficient to identify the four groups of plastics employed in this study: polystyrene, polypropylene, acrylonitryle-butadiene-styrene and acrylonitryle-butadiene-styrene/polycarbonate

The potential of laser-induced breakdown spectroscopy (LIBS) for the rapid determination of platinum in liquid silicone oils has been evaluated in the framework of on-line process control. A comparison of LIBS sensitivity between three setups designed for liquid analysis (static, liquid jet and flowing liquid) was performed using a 266 nm Nd/YAG laser irradiation. Best results were obtained using the flowing liquid setup and a similar limit of detection was obtained using the liquid jet. The effect of different buffer gases (Ar, He, N 2 , etc.) on the signal sensitivity was studied in liquid jet analysis and best values were obtained with a nitrogen sheath gas. Detection limits were in the 100 mg/kg range for both setups. Quantitative determination of platinum in real liquid samples was also investigated using both liquid jet and flowing liquid setups. Calibration curves were plotted for Pt with the liquid jet and the flowing liquid setups under optimised temporal acquisition parameters (delay time and gate width). A normalisation using a silicon line was applied and recovery ranged from 3 to 15 % for Pt in catalyst samples with both setups showing that LIBS is a sensitive and accurate method for online applications.