Sampling chamber with minimal wall surface for simultaneous emission testing of diisocyanates and diamines from polyurethane products

Abstract

A sampling chamber was developed for emission testing of diisocyanates, methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), and corresponding diamines, methylene diphenyl diamine (MDA), and toluene diamine (TDA) from polyurethane (PU) product surfaces. In addition, a methodology for validation of the sampling chamber was presented, based on the introduction of generated standard atmospheres of the different diisocyanates and diamines to the sampling chamber system. Sampling of diisocyanates and diamines was performed on a circular glass fiber filter (150mm diameter) impregnated with dihexyl amine (DHA) and acetic acid (AA) positioned inside a cylindrical stainless steel sampling chamber. The diisocyanates were immediately derivatized to DHA derivatives, and the amines were derivatized in a subsequent work-up procedure with ethyl chloroformate (ECF). The design of the sampling chamber and the presented methodology allowed for simultaneous sampling and analysis of diisocyanates and diamines of emission from a large surface area with minimal interior wall interaction in the sampling chamber. Performance characteristics of the sampling chamber for different sampling times and air humidity were obtained by determining collected amounts of the diisocyanates and diamines in the different parts of the sampling chamber. The repeatability of the collected amount on the impregnated filters in the sampling chamber was 15% with an overall recovery for 8h of sampling in the range of 61% to 96%. The performance of the sampling chamber was not affected by air humidity (5%-75% RH), and no breakthrough during sampling was observed. LC-MS/MS determinations allowed for emission testing of diisocyanates and diamines on product surfaces as low as 10-30ng m-2 h-1.