Determination of titanium, chromium, magnesium and aluminum in chromium-based ethylene polymerization catalysts by ICP-AES with internal standard method

The chromium-based ethylene polymerization catalyst was treated by microwave digestion, and aqueous sample solution was prepared. The selection of the analytical spectral lines for the measured elements was determined. The matrix effect in sample determination was discussed. The determination method of Cr, Ti, Mg and Al in chromium-based ethylene polymerization catalyst with microwave digestion technique and inductively coupled plasma atom emission spectrometry(ICP-AES)was established reliably. The high content of Cr element in solution had a significant effect on the determination of Ti, Mg and Al. Adding the mixed internal standard solution, the matrix interference to the measured elements was eliminated. According to the results, the linear correlation coefficient of the calibration curve of each element was not less than 0.999 8. The detection limits of Cr, Ti, Mg and Al were 0.001 05 mg/L, 0.001 35 mg/L, 0.000 66 mg/L and 0.002 34 mg/L, respectively. With this method, the recoveries were between 97.50% and 104.0%, and the relative standard deviations (RSD, n=6) were between 0.51% and 4.45%.