DETERMINATION OF HEXAVALENT CHROMIUM EMI

2.1 For incinerators and combustors, the Cr emissions are collected isokinetically from +6 the source: To eliminate the possibility of Cr reduction between the nozzle and impinger, the +6 emission samples are collected with a recirculatory train where the impinger reagent is continuously recirculated to the nozzle. Recovery procedures include a post-sampling purge and filtration. The impinger train samples are analyzed for Cr by an ion chromatograph equipped with a post-column +6 reactor and a visible wavelength detector. The IC/PCR separates the Cr as chromate (CrO ) from +6 = 4 other diphenylcarbazide reactions that occur in the post-column reactor. To increase sensitivity for trace levels of chromium, a preconcentration system may also be used in conjunction with the IC/PCR.