Determination of trace levels of titanium in polyolefin polymers by catalytic reduction using square wave voltammetry

Abstract

A sensitive and rapid method for the determination of trace levels of titanium in polyolefin polymers using square wave voltammetry is discussed. It involves ashing, acid digestion of polymer samples and determination of titanium(IV) by catalytic reduction using square wave voltammetric (SWV) technique. A well defined peak of titanium(IV) in Britton—Robinson buffer solution containing EDTA and KBrO 3 is observed in the potential range of −0.10 to −0.40 vs. Ag/AgCl. Calibration graphswere linear in the range 0.05–0.25 μg/ml for titanium. Effects of pH and concentration of bromate, EDTA and buffer constituents are studied for the optimization of experimental conditions. Interference from other concomitants present in the polymer matrix are studied. Low density polyethylene (LDPE) obtained by tubular process was used for preparing the synthetic standards in order to optimize the experimental conditions and good recoveries (99–101%) were obtained. The method was extended to different polyolefin samples and the results obtained for the titanium content compared with those obtained by UV/Vis spectrophotometry. Statistical evaluation showed no significant bias between the two methods. SWV is found suitable for the estimation of Ti in the range 1–50 μg/g in polyolefin polymers with a RSD < 2.0%.