Development and characterization of directly connected laser ablation/low-pressure inductively coupled plasma atomic emission spectrometry for solid sample analysis

Laser-ablation/low-pressure inductively coupled plasma spectrometry (LA/LP- ICP) has been developed and used for quantitative elemental analysis of Nat ional Institute of Standards and Technology (NIST) alloy samples. Laser abl ation was performed with a Nd:YAG laser operated in a Q-sw itched mode at 1 064 nm (100 mJ/pulse, 10 Hz). The ablation chamber and ICP torch were direc tly connected by the use of a step nozzle to improve the precision in measu rements and to focus the sample stream into the center of the torch. The pl asma in low-pressure argon atmosphere can be easily generated within a wide range of pressure (0.2-5.0 torr) and provides a very stable and clean spec trum at most wavelength regions. The generation of a plasma "core zone", wh ich gives a concentrated brilliant emission, is essential for the productio n of efficient plasma emission. The emission of the plasma was monitored wi th the use of an ultraviolet-visible fiber-optic bundle and an optical mult ichannel analyzer (OMA). The relative standard deviation (RSD) (%) value of the copper emission intensity without a step nozzle was 11.7%, while that with a three-step nozzle was reduced to about 3.0%. Linear calibration curv es were developed for the elements Cu (0.034-1.500%), Cd (0.0007-0.0155%), and Mn (0.0017-0.0480%). Detection limits [signal-to-noise (S/N) = 3] vary with the elements from 1.8 mu g/g for Mn to 70.7 mu g/g for Cu. Comprehensi ve details of our experimental apparatus and several discussions of the pro cess studies with the use of this LA/LP-ICP are reported in this work.