On Method 0061, can both chromium and Cr+6 be measured in the same test? If someone wanted only total chromium, wouldn’t it be better to run the multi-metal train (Method 0060)?

SW-846, Method 0061, Determination of Hexavalent Chromium Emissions From Stationary Sources, is applicable for the determination of Cr+6  from hazardous waste incinerators, municipal waste incinerators, and sewage sludge incinerators.  With the approval of the Administrator, this method may also be used to measure total chromium.

For total chromium, you would operate the Method 0061 sampling train in the same manner for Cr+6, but would rinse all active components of the sample train (from probe inlet to the fourth impinger) with 0.1 M HNO3 for total chromium.  Remember, one filters the insolubles from the 0.1 N KOH recovered solutions and analyze the insolubles for total chromium also (along with the 0.1 M HNO3 rinses).  Consequently, the total chromium number would be the Cr+6 number plus the insoluble total Cr number plug the 0.1M HNO3 total Cr rinse.

For total chromium only, it would be easier to operate the multi-metals train (SW-846, Method 0060, without the KMNO4 impingers for Hg) rather than the Cr+6 train because of the special adaptor for the probe assembly and recirculating first impinger.