EFFECTS OF LOW ACETIC-ACID CONCENTRATIONS IN INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY

The effects of low acetic acid concentration on selected analytical li nes (Mn II, Li 1, Cu I, Cu II, Cd I and Cd II) were studied as a funct ion of incident power and carrier gas flow rate, using an ARL 35000 C inductively coupled plasma spectrometer. Line intensity and line-to-ba ckground intensity ratios were measured for water and for 3 and 1 0% a cetic acid. The magnitude and mechanism of interference produced by ac etic acid were revealed from measured changes in the solution uptake r ate, the departure of the ratio of line intensity in acetic acid solut ion and that in water from unity and the changes in ion-to-atom line i ntensity 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 plasm a at compromise conditions for multi-element analysis (r.f. power, 120 0 W and carrier gas flow rate, 0.91 min-1, using matrix-matched calibr ation standards. Detection limits and relative standard deviation valu es for Fe, Cu, Cr, Ni, Pb, Al, Cd and Zn were almost equal for aqueous solution and solutions of 3 and 10% acetic acid.