DETERMINATION OF TRACE LEVELS OF TITANIUM IN POLYOLEFIN POLYMERS BY CATALYTIC REDUCTION USING SQUARE-WAVE VOLTAMMETRY

A sensitive and rapid method for the determination of trace levels of titanium in polyolefin polymers using square wave voltammetry is discu ssed. It involves ashing, acid digestion of polymer samples and determ ination of titanium(IV) by catalytic reduction suing square wave volta mmetric (SWV) technique. A well defined peak of titanium(IV) in Britto n-Robinson buffer solution containing EDTA and KBrO3 is observed in th e potential range of -0.10 to -0.40 V vs. Ag/AgCl. Calibration graphs were linear in the range 0.05-0.25 mu g/ml for titanium. Effects of pH and concentration of bromate, EDTA and buffer constituents are studie d for the optimization of experimental conditions. Interference from o ther concomitants present in the polymer matrix are studied. Low densi ty polyethylene (LDPE) obtained by tubular process was used for prepar ing the synthetic standards in order to optimize the experimental cond itions and good recoveries (99-101%) were obtained. The method was ext ended to different polyolefin samples and the results obtained for the titanium content compared with those obtained by UV/Vis spectrophotom etry. Statistical evaluation showed no significant bias between the tw o methods. SWV is found suitable for the estimation of Ti in the range 1-50 mu g/g in polyolefin polymers with a RSD<2.0%.