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Field comparison of IOMs and impingers for sampling of total aliphatic isocyanates in air with the map reagent.
Bello-D; Woskie-S; Youngs-F; Streicher-R; Liu-Y; Sparer-J
American Industrial Hygiene Conference and Exposition, June 2-7, 2001, New Orleans, Louisiana. Fairfax, VA: American Industrial Hygiene Association, 2001 Jun; :31
Results of a comparative field study on the performance of 25-mm inhalable samplers (IOM) and midget impingers for the collection of total isocyanates in air using the MAP reagent are presented here. Air sampling and analysis was performed according to the NIOSH MAP draft method 5525. Midget impingers, filled with 15 mil x 10-4 M MAP in butyl benzoate, were operated at 1l/min. IOM cassettes, loaded with 25-mm quartz fiber filters impregnated with 500mg MAP, were operated at 2 l/min. Filters were field extracted with 10 ml 1 x 10-4 M MAP in acetonitrile. 34 impinger-IOM pairs were collected in three shops during spray painting tasks. Regression analysis demonstrated that impingers and IOMs perform equally in their collection efficiency for both the monomer and total oligomer of biuret/isocyanurate (Y=1.0X, R2=0.98). A paired t-test comparing the IOMs to impingers for both the monomer and oligomer proved insignificant (Pr >0.9 two-sided), and remained so even after including three outliers (Pr>0.2). Intra-sampler variability was calculated from the individual coefficients of variation (CV) for the pairs. The CV was close to 10% (SD = 9%) for both samplers at typical total isocyanate concentrations of £ 400mg NCO/m3 and almost doubled at unusually high concentrations of 3lmg NCO/m3 due to the outliers. Previous field comparisons of impingers and filter samplers have found impingers to give higher results than filters. Explanations for the observed sampler agreement may include the following factors: 1) Slow curing aliphatic isocyanates derivatize completely on the filter; 2) Field extraction of filters; 3) Short sampling time (GM = 25 min, GSD=2.4); 4) Expected particle size was mostly 2-20mm. It is concluded that MAP impregnated filters can be successfully used for sampling of total aliphatic isocyanates in air.
Samplers; Impingers; Isocyanates; Air-samples; Reagents; Filters; Spray-painting; Monomers
American Industrial Hygiene Conference and Exposition, June 2-7, 2001, New Orleans, Louisiana