SENSITIVITIES OF INDUCTIVELY COUPLED PLASMA OPTICAL-EMISSION SPECTROMETRY FOR DRY AND WET AEROSOLS

The sensitivity of the inductively coupled plasma optical emission spectrometry (ICP-OES) signal was investigated for dry aerosols generated by spark discharges, as well as aerosols generated by a conventional ultrasonic nebulizer (USN). Particle sizes of the generated aerosols were < 300 nm and the ICP sensitivity was not influenced by particle size. The small amount of residual water after the desolvator (1.5 mg/min) did not change the plasma conditions, since the excitation temperature in the plasma remained constant within 61 K for the dry and wet aerosols. Nevertheless, mixing of the dry aerosol with H2O/HNO3 droplets resulted in a reduction of the ICP signal by 43.1% which could be attributed to scavenging of analyte particles by the droplets generated in the USN. An absolute calibration of the ICP-OES signal by neutron activation analysis was performed using silver aerosols. With these calibration data the nebulizing efficiency of the USN was determined, and a value of (5.2 +/- 0.5)% was found.