Development and Characterization of Directly Connected Laser Ablation/Low-Pressure Inductively Coupled Plasma Atomic Emission Spectrometry for Solid Sample Analysis

Abstract

Laser-ablation/low-pressure inductively coupled plasma spectrometry (LA/LP-ICP) has been developed and used for quantitative elemental analysis of National Institute of Standards and Technology (NIST) alloy samples. Laser ablation was performed with a Nd:YAG laser operated in a Q-switched mode at 1064 nm (100 mJ/pulse, 10 Hz). The ablation chamber and ICP torch were directly connected by the use of a step nozzle to improve the precision in measurements and to focus the sample stream into the center of the torch. The plasma 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 spectrum at most wavelength regions. The generation of a plasma “core zone”, which gives a concentrated brilliant emission, is essential for the production of efficient plasma emission. The emission of the plasma was monitored with the use of an ultraviolet-visible fiber-optic bundle and an optical multichannel 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 curves 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 μg/g for Mn to 70.7 μg/g for Cu. Comprehensive details of our experimental apparatus and several discussions of the process studies with the use of this LA/LP-ICP are reported in this work.