Determination of nonmetals using ICP-AES-techniques

Abstract

The determination of iodine, bromine, sulphur and phosphorus using different modes of sampling in ICP-AES is described. Detection limits in the range of some 10 μgL⁻¹ have been obtained using directly aqueous solutions with pneumatic nebulization. The influence of several anions and metals has been investigated. The addition of methanol and ethanol have improved sensitivities but decreased signal-to-background ratios and detection limits due to extended blank values and increased standard deviations. Using ultrasonic nebulization the sensitivities and the detection limits could be enhanced for these elements in aqueous solutions, but a significant decrease in sensitivity has been observed using additives as methanol or ethanol. By coupling of pneumatic nebulization and gas generation of iodine by addition of oxidizing agents, the detection limits of iodine could be improved to 6 ngL⁻¹ at the 178.28 nm line. Electrothermal vaporization has sucessfully been applied for microsampling of nonmetals and ICP-AES determination. Using aqueous solutions without any modifier the following absolute detection limits at the S (180.73 nm), P (178.27 nm), I (178.28 nm) and Br (163.34 nm) lines have been obtained: 0.25 ng of S, 0.44 ng of P, 0.36 ng of I and 43 ng of Br.