TECHNICAL MEMORANDUM 

DATE: September 28, 2015 

SUBJECT: Proposal to remove EPA Methods 18, 320, and ASTM D6348-03 as acceptable methods for 

measuring total VOC under 40 CFR 60, Subpart JJJJ 

FROM: Steffan Johnson – OAQPS AQAD Measurement Technology Group Leader 

TO: Docket # EPA-HQ-OAR-2014-0292-0001 

Background 

On September 8, 2015 the Measurement Technology Group of the EPA published proposed revisions to 

Test Methods, Performance Specifications, and Testing Regulations for Air Emission Sources (80 FR 

54146). In this rulemaking, we propose to remove EPA Methods 18, 320, and ASTM D6348-03 as 

acceptable methods for measuring total Volatile Organic Compounds (VOC) under 40 CFR 60, Subpart 

JJJJ. It has come to our attention that we have not supplied sufficient information supporting our 

rationale for making this change in the rule package and docket. The intent of this memo is to provide

the rationale for this proposed action. 

For clarification we would also point out that the September 8, 2015 proposal did not remove an option

to use Method 320, ASTM 6348, and EPA Method 18 for methane and ethane determination, however 

this is not clearly stated in the preamble of the Revisions to Test Methods, Performance Specifications, 

and Testing Regulations for Air Emission Sources; Proposed Rule (80 FR 54146). 

The EPA recognizes that the measurement technologies used in these methods are appropriate for the 

purpose of measuring specific organic compounds, and will continue to specify their use for compliance

measurement for this purpose. While these measurement techniques excel in speciated VOC 

measurements, Methods 18, 320 and ASTM D6348-03 are not robust total VOC measurement methods 

as currently required by Subpart JJJJ, where the measurement result is the basis for determination of 

compliance with a total VOC emissions limit. 

EPA Methods 18, 320, and ASTM D6348-03 were included in ”Standards of Performance for Stationary 

Spark Ignition Internal Combustion Engines” 40 CFR 60, Subpart JJJJ in 2008 (73 FR 3568) as alternative 

methods to Method 25A, based on recommendations by two commenters (EPA-HQ-OAR-2005-0030-

0150 - American Petroleum Institute and EPA-HQ-OAR-2005-0030-0157 - Interstate Natural Gas 

Association of America) during the comment period of the proposed rule dated June 12, 2006 (71 FR 

33804). Both commenters specifically requested use of EPA Method 320 for measurement of nitrogen 

oxides and carbon monoxide. Both commenters also requested the need for a method to determine 

non-methane hydrocarbons and proposed use of Method 18 and pointed out that a “validated” FTIR 

method could also be acceptable. 
Discussion 

The proposed removal of EPA Method 320 and ASTM D6348-03 (both of which rely on Fourier 

Transform infrared (FTIR) technology) is due to the lack of a consistent, demonstrable, and validated 

approach to measuring total VOC emissions, primarily due to the lack of a discrete list of compounds 

identified as those constituting the total VOC for the emissions sources affected by this rule. Since 

promulgation of the revisions to Subpart JJJJ in 2008, EPA’s Office of Air Quality Planning and Standards, 

Measurement Technology and Measurement Policy Groups have been unable to provide adequate 

technical assistance to regulatory agencies who must make compliance determinations for Subpart JJJJ 

sources with data collected using these methods. The complexity of attempting to accurately quantify a 

total VOC value using FTIR technology should not be underestimated. 

A primary point of concern is that neither EPA Method 320 nor ASTM D6348-03: 

(1) Include procedures and quality assurance /quality control processes for conducting a 

summed measurement of large numbers of VOC analytes or, 

(2) Describe how this sum equates to total VOC in the sampled gas streams. 

The list of potential VOC species which must be addressed by a total VOC method is extensive. EPA 

defines VOC in §60.2 as “...any organic compound which participates in atmospheric photochemical 

reactions; or which is measured by a reference method, an equivalent method, an alternative method, 

or which is determined by procedures specified under any subpart”. 

In addition, the applicability, accuracy, and precision of FTIR measurements are influenced by a number 

of interrelated factors, which may be divided into two classes: Sample-independent and sampledependent factors, and these factors must be considered for each analyte measured with this approach. 

 

Examples of sample independent factors are system configuration and performance (e.g., detector 

sensitivity and infrared source output), quality and applicability of reference absorption spectra, and 

type of mathematical analyses of the spectra. These factors define the fundamental limitations of FTIR

measurements for a given system configuration. These limitations may be estimated from evaluations of 

the system before samples are available. For example, the detection limit for the absorbing compound 

under a given set of conditions may be estimated from the system noise level and the strength of a 

particular absorption band. Examples of sample-dependent factors are spectral interferents (e.g., water 

vapor and CO2, both present in quantity from engine emissions) or the overlap of spectral features of 

different compounds and contamination deposits on reflective surfaces or transmitting windows. To 

maximize the effectiveness of the mathematical techniques used in spectral analysis, identification of

interferents (a standard initial step) and analysis of samples (including the effect of other analytical 

errors) are necessary. As stated above, such measurement interferences and effects must be 

understood for each analyte measured, thus exacerbating the difficulty of measurement where a large 

number of individual compounds are present (or may be present) in the emissions stream. 

EPA Method 320 incorporates method specific data validation processes by which data collected is 

quality controlled and assured; likewise, ASTM D6348-03 includes a number of Annexes that perform a 

similar function. Appropriate use of these QA/QC procedures requires a full understanding of the 

individual compounds being measured along with the gas matrix containing the compounds, such that 

the QA/QC challenges presented to the sampling and analytical systems are appropriate to qualify the 
most difficult to measure compounds. With an extensive list of compounds to be measured, such 

QA/QC procedures to validate these data are both expensive and time consuming. 

Another concern that complicates measurement of total VOC using these FTIR methods is the variability 

of the matrix of pollutant species that make up total VOC emissions from engine exhaust. The EPA does

not have sufficient information in hand to know when Methods 320 or ASTM D6348-03 have actually 

measured and correctly quantified each constituent VOC in the exhaust stream, unless each compound 

has been validated through the QA/QC procedures outlined in Section 13.0 of Method 320 or Annex 5 of 

ASTM D6348-03. We also recognize that the potential VOC compounds emitted from an internal 

combustion engine vary depending on several factors including but not limited to fuel type (engines 

combusting No. 2 diesel will have a different VOC emission profile than engines combusting landfill gas, 

bio gas, ag-grade diesel, or one combusting field gas at an upstream oil and gas facility). Other factors 

influencing variable emissions include (but are not limited to) engine maintenance, age, make-up air 

temperature, and humidity. Additionally, we are aware that many FTIR measurement approaches are 

not sensitive enough to individually quantify all compounds present, and may not quantify benzene, 

toluene, ethylbenzene, and xylenes (BTEX) due to water interference, a common concern with FTIR 

measurement. Furthermore, we have apprehensions with the ability of FTIR device software to correctly 

identify and quantify the potential target compounds in the engine exhaust such as speciation of C3+ 

alkane mixtures to properly account for number of carbons for proper conversion to a propane basis. 

It is our understanding that following promulgation of the revisions to Subpart JJJJ in 2008, some 

compliance test protocols have been submitted where emissions test firms base compliance testing on 

an approach to measure total VOC by quantifying a specific list of VOC compounds they believed to best

match the effluent of Subpart JJJJ engines. This may be a credible way to perform speciated VOC 

sampling for those targeted compounds, however we have not seen any evidence to support that such a 

targeted list represents the total VOC from these sources, much less during different operations or when 

burning different fuels. As such, this VOC list has been determined by the tester or an instrument 

vendor, and not the regulatory authority. 

These target compound lists are very important, as they may not meet the definition of “total volatile

organic compounds” as stated in Subpart JJJJ, and the associated measurement would then not 

demonstrate compliance. For these reasons, we are proposing to remove Method 320 and ASTM 

D6348-03 as total VOC compliance methods from Subpart JJJJ until there is an establishment of a 

comprehensive, standardized measurement protocol that can be used to accurately identify and 

quantify a value representative of total VOC from the wide variety of these engine and fuel emissions 

profiles. 

We believe that establishment of a comprehensive standardized protocol for FTIR measurement of total 

VOC under Subpart JJJJ is dependent on developing an understanding of some very complex concerns. 

First, a sufficient catalog of speciated VOC emissions data from a wide variety of engine exhausts must 

be developed to determine if a discrete list of VOC compounds could be derived for each process 

configuration (engine and controls) and fuel type. This information could then be used to design a total 

VOC measurement approach which accurately quantifies each compound in a specified list of VOC list 

representative of the total VOCs from a given process and control configuration. Additionally, we would 

need to evaluate the suite of VOC emissions from such lists to determine applicable target analytes for 

spiking and recovery studies, and from there would be also be the need to develop a list of standard 

response factors with which to equate the speciated VOC to a propane basis for a final compliance 

determination. While this represents a substantial amount of work, it is not insurmountable, although
we are lacking the raw data with which to begin such analysis, making a timeline to resolution lengthier 

than we would like. 

Unlike the FTIR methods discussed above, EPA Method 18 does include guidance for total VOC 

measurement which involves a process known as “screening” whereby the source is pre-surveyed prior 

to conducting the emissions test for all possible VOC compounds according to Section 16.1 of Method 

18. Compounds that are detected in a measureable quantity during this intensive screening process are

then targeted in the subsequent compliance test. We find this procedure impractical for use in subpart

JJJJ as the wide scope of sampling protocols involved, and subsequent calibration and QA/QC 

requirements (use of calibration standards for and spiking of each VOC to be quantified) required to 

conduct Method 18 would be exceedingly costly, rendering the requirement to conduct such a presurvey at each source as cost prohibitive. Indeed, to date, no data has been presented to EPA showing 

speciated VOC sampling according to Method 18 as accurate or viable, though it may be achievable 

through a good deal of effort and expense. Like with the FTIR, we believe a comprehensive 

measurement protocol could be developed for GC measurement based upon a sufficient catalog of 

Method 18 screening data from a wide variety of engine exhausts (engine, controls and fuel type) to 

develop a target list of VOC compounds. 

With the proposed removal of EPA Methods 18 and 320, as well as ASTM D6348-03 for use in measuring 

total VOC under Subpart JJJJ, owners and operators must use EPA Method 25A as the methodology to 

perform VOC measurements. Method 25A measures the aggregate of total VOC that respond to the FIA 

detector as measurement of total VOC as defined by §60.2. Using EPA Method 25A to determine 

compliance with the emission limit incorporates the reduced response of the aldehydes and other 

oxygenated organics considered when the emission limits were set and therefore remains consistent 

with the procedures used to establish the emission limit. 

Closing 

The EPA recognizes the utility of both GC and FTIR technologies and has routinely required their use in 

air emissions standards; however, we are concerned that current implementation of these test methods 

under Subpart JJJJ does not provide for proper and consistent quality assurance for compliance 

demonstration with total VOC measurement as required by the subpart. Because of these concerns and 

implementation issues, we are proposing to remove the use of Method 18, Method 320, and ASTM 

D6348-03 for total VOC compliance determination under 40 CFR 60 Subpart JJJJ. 

We are interested in identifying a standardized approach that would provide consistent and repeatable 

measurement of total VOC using these techniques, and whereby we could again allow the use of these 

test methods to demonstrate compliance for total VOC emissions limit(s) under Subpart JJJJ. How 

quickly the EPA can proceed on this path will depend on our access to data necessary in order to 

develop the protocol laid out above.