DETERMINATION OF NONMETALS USING ICP-AES-TECHNIQUES

The determination of iodine, bromine, sulphur and phosphorus using dif ferent modes of sampling in ICP-AES is described. Detection limits in the range of some 10 mu gL(-1) have been obtained using directly aqueo us solutions with pneumatic nebulization. The influence of several ani ons and metals has been investigated. The addition of methanol and eth anol have improved sensitivities but decreased signal-to-background ra tios and detection limits due to extended blank values and increased s tandard deviations. Using ultrasonic nebulization the and the detectio n limits could be enhanced for these elements in aqueous solutions, bu t a significant decrease in sensitivity has been observed using additi ves as methanol or ethanol. By coupling of pneumatic nebulization and gas generation of iodine by addition of oxidizing agents, the detectio n limits of iodine could be improved to 6 ngL(-1) at the 178.28 nm lin e. Electrothermal vaporization has successfully been applied for micro sampling of nonmetals and ICP-AES determination. Using aqueous solutio ns 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.