Improving the analytical performances of ICP-AES by using a high-temperature single-pass spray chamber and segmented-injections micro-sample introduction for the analysis of environmental samples

Abstract

A new method based on the use of a high-temperature single-pass spray chamber and the injection of a sample plug into an air carrier gas stream was developed to mitigate non-spectral interferences caused by inorganic concomitants and to reduce plasma loading in inductively coupled plasma atomic emission spectrometry (ICP-AES). The evaluated sample introduction systems were a 10 cm³ inner-volume single-pass spray chamber (also called the Torch Integrated Sample Introduction System, TISIS) with and without heating and a cinnabar spray chamber, taken as a reference device. The temperature of the spray chamber was raised up to 350 °C. Sensitivity, memory effects, limits of detection and non-spectral interferences were evaluated. The results proved that the higher the chamber walls temperature, the higher the peak height and the lower the memory effects. The single-pass spray chamber heated at 350 °C provided lower limits of detection (0.3–2.3 μg l⁻¹) compared with the reference spray chamber (1–33 μg l⁻¹) and a significant reduction of matrix effects. This device was successfully applied to the analysis of environmental certified reference materials, such as marine sediments and animals. The calibration curve was obtained by modifying the mass of the analyte injected, thus requiring only one standard solution. The results were also compared with those obtained by external calibration (both at room temperature and at 350 °C) and single-point standard addition. The analytical bias was lower than 5%, showing that this sample introduction system is adequate to remove the matrix effects due to inorganic concomitants, allowing the accurate analysis of environmental samples.