3122
Anal. Chem. 1986, 58, 3122-3125
Determination of Aqueous Bromide, Iodide, and Chloride with Pneumatic and Ultrasonic Nebulization into a Helium Microwave-Induced Plasma Kevin G. Michlewicz and Jon W. Camahan* Department of Chemistry, Northern Illinois University, DeKalb, Illinois 60115
A helium mlcrowave-induced plasma (He-MIP) was investigated for the determinatlon of halides in aqueous solutlons. The plasma was operated at 2450 MHr and 500 W. The optimum plasma gas flow rate was 21 L/mln. A modlfled He-MIP torch provides greater mechanical stablllty and more efficient analyte-plasma contact than that of the earlier design presented by thls group. Sample nebullzatlon was accomplished wlth a MAK pneumatic (PN) system (with and without desolvation) and an ultrasonlc (USN) system (with desolvation). Detectlon llmits wlth USN were as follows: CI, 0.4 mg/L; Br, 3 mg/L; and I, 0.8 mg/L. Detection limlts wllh Pff (without desolvation) were as follows: CI, 2 mg/L; Br, 60 mg/L; and I , 7 mg/L. The Interference effects of selected metals were examined and found to be moderate with pneumatic nebulization and significant with ultrasonk nebullratlon.
Direct determinations of aqueous nonmetals by elemental emission in the visible spectral region has proven to be difficult. This problem is due to the high energy levels to which nonmetals must be promoted to produce elemental emission in the visible spectral region. Most nonmetal atomic emission experiments have been limited to the introduction of analyte in the gas phase using gas chromatography (1-8), electrothermal vaporization (9, l o ) , or volatile compound formation (11-15). Subsequent detection has generally been accomplished using a low-power (
