Why is FRM Method 18 not recommended for HAP testing? Where could FRM Method 18 be used?

Federal Reference Method 18 was promulgated in the Federal Register,

48 FR 48344, October 10, 1983.  Since that time, the method has undergone corrections and updates.  On April 22, 1994, the method underwent an update for improving the quality assurance/quality control (QA/QC) sections of FRM 18.

When originally promulgated, the method was intended to be used as both a survey method to gain information as to what organics were being emitted from industrial sources and as input to agency models for regulatory activities.  FRM 18 is very similar to SW-846, Method 0040, Sampling of Principal Organic Hazardous Constituents from Combustion Sources Using Tedlar Bags.  Both methods are sample collection methods, with references to other FRM or SW-846 analytical methods for the analysis of the specific target compound list.  However, FRM 18 goes into great detail on how to analyze the survey Tedlar bag on-site by using various techniques for calibrating the gas chromatography system.

As identified in Section 2.1 of FRM 18, the “range of this method is from about 1 part per million (ppm) to the upper limit governed by GC detector saturation or column overloading.  The upper limit can be extended by diluting thgases with an inert gas or by using smaller gas sampling loops.”  Consequently, FRM 18 is truly applicable to those sources with emissions of gaseous organic compounds in the ppm range.  Since the method allows for “dilution” of the stack gas with inert gas using a Tedlar bag technique, the method is not sensitive to low ppb levels of organics.  As you recall in SW-846, Method 0030, we used a Tenax, Tenax/charcoal tubes to capture the hazardous organic constituents from the stack gas.  After collection, we performed a “thermal desorption” on the tubes to reach the desired detection limits needed for risk base calculations.  Those detection limits were in the 1 ppb range.  Whereas, SW-846, Method 0040 is in the 100s ppb range and FRM 18 in the 1 ppm range.