Use of factorial design for evaluation of plasma conditions and comparison of two liquid sample introduction systems for an axially viewed inductively coupled plasma optical emission spectrometer

A factorial design was applied to evaluate plasma conditions employing the Mg II 280/Mg I 285 nm intensity ratio in an axially viewed inductively coupled plasma optical emission spectrometer using different sample introduction devices: a concentric or a V-groove nebulizer and a cyclonic or a Sturman-Masters spray chamber. Effects of nebulizer gas flow-rate on Mg II/Mg I ratio were different in each introduction system. Robust conditions were obtained at low nebulizer gas flow-rate when using concentric nebulizer with a cyclonic spray chamber or a concentric nebulizer and a Sturman-Masters spray chamber. However, when using a V-groove nebulizer with a Sturman-Masters spray chamber, Mg II/Mg I ratio increased at high nebulizer gas flow-rates. Recovery experiments for a milk standard reference material diluted in water-soluble tertiary amines in both robust and non-robust conditions indicated that the robust condition was reached at higher nebulizer gas flow-rates and led to better accuracy and precision when using a V-groove nebulizer.