A sequential tape monitor for toluene diisocyanate

An electronic microcircuit controller has been designed to convert a commercially available continuous tape monitor for toluene diisocyanate (TDI) into a sequential sampler in order to eliminate deficiencies in response and resolution of fluctuating TDI concentrations. The modified monitor will collect up to fourteen 12-min samples per work shift. The sensitivity of the monitor was doubled approximately by the inclusion of a blue filter in the optics of the reader unit. Recalibration of several modified monitors indicated a wide range in response to TDI necessitating individual calibrations. No significant difference in response to the 2,4 and 2,6 isomers of toluene diisocyanate was noted for modified personal monitors, in contrast to a 25% lower response to 2,6-TDI by an area monitor in which the same detection tape was used. The modified monitor has shown a reliability rate of about 90% during a three-year field survey of TDI exposures.