Characterization of implant device materials using size-exclusion chromatography with mass spectrometry and with triple detection.

A more complete understanding of the raw materials used for making implant device materials becomes increasingly important in the medical device industry. Often such detailed information requires utilization of a combination of analytical techniques. In this work, we characterize a poly(dimethyl siloxane) (PDMS) material using on-line size exclusion chromatography (SEC) with electrospray ionization (ESI) and matrix assisted laser desorption ionization (MALDI) mass spectrometry (MS) techniques. Here, we obtain detailed molecular compositional information such as repeat units, end group chemistry, and identification of impurities in both the high and low mass range. SEC with light scattering, viscosity, and refractive index detection (triple detection) is used to obtain information on a small quantity of high mass impurity that was undetected by both SEC-ESI and MALDI MS techniques. SEC with triple detection measures absolute molecular weights and molecular weight distributions. We compare average molecular weight values of the implantable device polymer obtained by SEC with triple detection, SEC-ESI, and SEC-MALDI MS techniques.