Analysis of the breakthrough of diisocyanates from a generated aerosol using the Occupational Safety and Health Administration Method number 42

Abstract

When sampling for isocyanates utilizing OSHA methodology, a glass fiber filter coated with I-(2-pyridyl)piperazine is used for collection. For OSHA Method 42 which is used for 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, and 1,6-hexamethylene diisocyanate, either 0. I mg or I mg of I-(2-pyridyl)piperazine can be used to coat the filter. Previous research has indicated that considerable breakthrough of isocyanates occurs when using glass fiber filters coated with 0. I mg of I-(2-pyridyl)piperazine. This causes underestimation of the isocyanates present within the sampled environment. No breakthrough of isocyanate was detected in this study with the glass fiber filters coated with I mg of I-(2-pyridyl)piperazine. Isocyanate concentrations ranged from below the threshold limit value(TLV) of 0.034 mg/m3 to levels approaching 8 times the TLV. The experimental design allowed both laboratory and industrial settings to be included in the research. This research was performed using a Berglund-Liu Aerosol Generator which is capable of producing monodisperse aerosol particles. Aerosol particles consisting of a mixture of 2,6-toluene diisocyanate, 2,4-toluene diisocyanate, and 1,6-hexamethylene diisocyanate with diameters of 6 and 10 um were collected on coated glass fiber filters. Also, an industrial environment was sampled during spray painting using isocyanate containing paint. The filters from both the laboratory and industrial settings were analyzed by Mgh Performance Liquid Chromatography and scanning electron microscopy. Using a scanning electron microscope, blank filters, filters with I-(2-pyridyl)piperazine and sampled filters were imaged. The images from the paint samples provide information on the microscopic level. The paint particles are integrated throughout the matrix of the filter at a 1,6-hexamethylene diisocyanate concentration near the TLV. The surface of the paint particles is not smooth but contains crater-like irregularities. The reaction in the micron-sized particle between the individual paint components is not complete when the aerosol particle is formed and impacts the coated glass fiber filter.