Malin Frick-Engfeldt, E. Zimerson, D. Karlsson
Jan 1, 2007
Citations
0
Influential Citations
32
Citations
Journal
Contact Dermatitis
Abstract
We have previously shown that the concentration of diphenylmethane‐4,4′‐diisocyanate (4,4′‐MDI) in commercial test preparations was so low that patch testing with the same was not reliable. The stability of 4,4′‐MDI in petrolatum (pet.) was compared with pet. preparations of polymeric diphenylmethane diisocyanate (PMDI), which consists of a complex mixture of monomeric isomers and oligomers of MDI. Preparations of 4,4′‐MDI and PMDI were stored under 3 different conditions, i.e. at room temperature, refrigerated and frozen. They were analysed continuously during 1 year with regard to the content of 4,4′‐MDI, 3‐ring oligomers and 4‐ring oligomers using liquid chromatography–mass spectrometry. PMDI preparations kept frozen were stable for a year. All other preparations failed to fulfil the requirements of stability, i.e. ±20% of the initial concentration. Storage in a freezer prolonged the lifetime for 4,4′‐MDI. The decrease in concentration for preparations kept at room temperature and refrigerated was less rapid in PMDI preparations than in 4,4′‐MDI preparations. PMDI preparations are better suited for patch testing patients exposed to MDI because they are more stable and homogeneous than 4,4′‐MDI preparations. They better reflect possible allergens that workers are exposed to because products used in industry contain both monomers and oligomers.