[Determination of impurities in K2Cr2O7 by an inductively coupled plasma spectrometer]

The trace elements Si, Al, Fe, Ca, Mn, Mg, and Cl in the K2Cr2O7 produced by chromate cleaner production were determined by a sequential inductively coupled plasma spectrometer in this paper. Matrix effect was studied and eliminated through matrix matching. The analytical conditions for the elements were optimized. Incident power of the RF generator was 0.95 kW. Pressure of carrier gas flow was 0.13 MPa, and its flow rate was 1.2 L x min(-1). Auxiliary gas flow rate was 0.2 L x min(-1). The element Cl was indirectly determined by the method of AgCl precipitation. The ion Cl- can be completely precipitated in 6% nitric acid system, and then determined after keeping the solution at 50 degrees C for two hours. The recoveries of the studied impurities range from 95% to 104%, and the relative standard deviations are lower than 4% (n = 10). Detection limits of these impurities are in a range 0.0001%-0.00001% (w/w). The analytical results of random samples agree well with the results using the standard-adding method, and the relative error varies from -4.27% to +5.26%. The developed method has been applied to the determination of impurities in K2Cr2O7 product with satisfactory results.