Determination of Hexavalent Chromium Emissions from Stationary Sources
This method provides procedures for the determination of hexavalent chromium (Cr+6) emissions from hazardous waste incinerators, municipal waste incinerators, municipal waste combustors, and sewage sludge incinerators. This method may also be used to measure total chromium given proper approvals of the governing regulatory agency. SW-846 Method 0013 has been superceded by SW-846 Method 0061. This method is similar to EPA Methods 306 / 306A.
Samples are collected isokinetically from a source using a sampling train composed of glass, quartz, Tygon or Teflon where there is contact with the sample gas. The train consists of a glass nozzle, Teflon aspirator to recirculate impinger reagent continuously to the nozzle, Teflon line and a series of four Teflon impingers. It is designed for sources with temperatures < 300°F.
For sampling, Impinger 1 is filled with 140mL of 0.1N KOH. Impingers 2 and 3 are filled with 80mL of 0.1N KOH and Impinger 4 is left empty. The Teflon impingers are followed by a glass impinger that is filled with 200-400g of silica gel.
Once sampling is complete, measure the volume of Impingers 1-3 and the silica gel impinger to determine the moisture content of the stack gas. The contents of impingers 1-3 are combined. The inside of the nozzle, aspirator, sample lines, impingers and connecting tubing are rinsed four times with deionzied water. This rinse is combined in a polypropylene container with the impinger contents.
The method allows for the determination of total chromium by ICP or GFAA. If total chromium is needed, the sampling train is rinsed three times with nitric acid (HNO3) following the water rinse. This rinse is collected in separate container.
The sample collected for hexavalent chromium is analyzed using IC/PCR following SW-846 Method 7199 procedures. This method states that the holding time for hexavalent chromium is 24 hours from sampling to collection. However, Method 0061 extends this holding time to 14 days because the sample is stabilized in the alkaline impinger solution.
When the lab receives the sample, the pH is determined and the sample filtered to remove insoluble matter and analyzed by IC/PCR. The filter can be digested with HNO3 and then analyzed for total chromimum. It is discarded if this analysis is not needed.
If the sample data are to be used for compliance purposes, the method requires that an audit sample be obtained and submitted with the samples to the laboratory for analysis.