An improved method was developed and validated for measuring low-level concentrations of toluene diisocyanates (TDIs) in air. The method is based on OSHA Method 42 for industrial applications. Airborne TDIs were trapped on a 25-mm glass-fiber filter impregnated with 50 µg of 1-(2-pyridyl)piperazine. A filter holder for was constructed to minimize contamination and losses of the analytes. The derivatized TDIs were extracted by immersion of the filter in a small volume of solvent. The analysis was performed with a high performance liquid chromatograph equipped with a fluorescence detector and a C18 base-deactivated silica column.
The modified method has a lower limit of quantitation of 0.02 ppb in 15 L of air for both 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI), which is about a fifteen-fold enhancement over Method 42. The recovery efficiencies and 95% confidence intervals for vapor-spiked filters were 77 ± 6 percent for 2,4-TDI and 69 ± 10 percent for 2,6-TDI. The precision of replicate analyses was ten percent or better. The method was used to screen flexible polyurethane foam for emissions of unreacted TDIs.
An improved method was developed and validated for measuring low-level concentrations of toluene diisocyanates (TDIs) in air. The method is based on OSHA Method 42 for industrial applications. Airborne TDIs were trapped on a 25-mm glass-fiber filter impregnated with 50 µg of 1-(2-pyridyl)piperazine. A filter holder for was constructed to minimize contamination and losses of the analytes. The derivatized TDIs were extracted by immersion of the filter in a small volume of solvent. The analysis was performed with a high performance liquid chromatograph equipped with a fluorescence detector and a C18 base-deactivated silica column.
The modified method has a lower limit of quantitation of 0.02 ppb in 15 L of air for both 2,4-toluene diisocyanate (2,4-TDI) and 2,6-toluene diisocyanate (2,6-TDI), which is about a fifteen-fold enhancement over Method 42. The recovery efficiencies and 95% confidence intervals for vapor-spiked filters were 77 ± 6 percent for 2,4-TDI and 69 ± 10 percent for 2,6-TDI. The precision of replicate analyses was ten percent or better. The method was used to screen flexible polyurethane foam for emissions of unreacted TDIs.