Polyolefines are the most common plastics. The most
widely used technology for preparing polyolefines
is the coordination polymerization. Usually metal chlorides or metal oxides are used. The most common catalyst, the so-called Ziegler-Natta-catalysts, consists of titanium chloride in combination with the cocatalyst triethylaluminum. Polyolefines are usually resistant to higher temperature and to many solvents. For trace metal determi
nations dissolved samples are necessary and which requires a rigorous sample preparation step. This includes a microwave digestion procedure
1, 2. Many analytical methods are available for the det
ermination of trace metals, including atom
absorption spectroscopy (AAS), optical emission spe
ctroscopy (OES), and inductively coupled-plasma mas
s spectrometry (ICP-MS). ICP-MS methods for trace metal determination achieve low detection limits and fast analysis times.
In this work typical elements like aluminum, titanium, magnesia, and silicon from a Ziegler-Natta-catalyst system were determined with ICP-MS and AAS, including previous microwave digestion. Different acids and their mixtures e.g. nitric acid, hydrofluoric acid, phosphoric acid, sulfuric acid, and hydrogen peroxide were used for sample dissolution. High pressure (100 bar) closed-vessels were employed for the microwave digestion w
hich was performed at temperatures ranging from 180 to 220 °C. It was found that stirring was very important during the microwave digestion. The different analytical methods were compared with each other. The results of the ICP-MS
show the lowest detection limits. Detection limits
for aluminum, titanium, and magnesia were lower tha
n 1 ppb and for silicon not lower than 100 ppb