Effects of low acetic acid concentrations in inductively coupled plasma atomic emission spectrometry

Abstract

The effects of low acetic acid concentration on selected analytical lines (Mn II, Li I, Cu I, Cu II, Cd I and Cd II) were studied as a function of incident power and carrier gas flow rate, using an ARL 35000 C inductively coupled plasma spectrometer. Line intensity and line-to-background intensity ratios were measured for water and for 3 and 10% acetic acid. The magnitude and mechanism of interference produced by acetic acid were revealed from measured changes in the solution uptake rate, the departure of the ratio of line intensity in acetic acid solution and that in water from unity and the changes in ion-to-atom line intensity ratio. Trace metal determination in 3% acetic acid, used as a ‘model’ solution in health control of packing materials, and in 9–10% vinegar was carried out by direct aspiration of sample into the plasma at compromise conditions for multi-element analysis (r.f. power, 1200 W and carrier gas flow rate, 0.9 l min^–1, using matrix-matched calibration standards. Detection limits and relative standard deviation values for Fe, Cu, Cr, Ni, Pb, Al, Cd and Zn were almost equal for aqueous solution and solutions of 3 and 10% acetic acid.