Location and concentration of ionic impurities in polymeric cable insulation

Two analytical methods for identifying ionic species and their concentration in cable insulation and shields are described and evaluated. Wavelength dispersive X-ray spectroscopy (WDX) is a microanalytical method that is applied to identify ions present and to determine their spatial distribution. Ion chromatography (IC) is a bulk analytical method that detects ions extracted from a specimen of cable insulation of shield material. The former method is tedious, expensive, and semiquantitative, but offers high spatial resolution and is nondestructive. Ion chromatography, on the other hand, provides an inexpensive means to identify ions and to measure their concentration precisely. The methods differ in their elemental sensitivity and ability to identify compounds. Each has its own specimen preparation requirements. Analytical results obtained from pairs of unaged and aged XLPE insulated cables are compared, using both methods, and some conclusions are drawn regarding the significance of the observed ionic changes.<>