Background Information: 

OTHER TEST METHOD 28 — April 15, 2009 

DRY IMPINGER METHOD FOR DETERMINING CONDENSABLE PARTICULATE 

EMISSIONS FROM STATIONARY SOURCES 

1. Scope and Applicability 

1.1 Scope. The U.S. Environmental Protection Agency (U.S. EPA or 

“we”) developed this method to describe the procedures that the 

stack tester (“you”) must follow to measure condensable 

particulate matter (CPM) emissions from stationary sources. This 

method includes procedures for measuring both organic and 

inorganic CPM. 

1.2 Applicability. You can use this method to measure CPM from 

stationary source emissions after filterable particulate matter 

has been removed. CPM is measured in the emissions after removal 

from the stack and after passing through a filter. You can use 

Method 17 to collect condensable and filterable particulate 

material from sources operating at stack temperatures and/or 

samples collected below 30°C (85°F) if the filter is treated as 

described in Sections 8.5.4.4 and 11.2.1 of this method. You may 

use this method only for stationary source emission measurements. 

1.3 Responsibility. You are responsible for obtaining the 

equipment and supplies you will need to use this method. You must 

also develop your own procedures for following this method. 

This category (Other Test Methods) includes test methods which have not yet been subject to the 

Federal rulemaking process. Each of these methods, as well as the available technical 

documentation supporting them, have been reviewed by the Emission Measurement Center staff 

and have been found to be potentially useful to the emission measurement community. The types 

of technical information reviewed include field and laboratory validation studies; results of 

collaborative testing; articles from peer-reviewed journals; peer-review comments; and quality 

assurance (QA) and quality control (QC) procedures in the method itself. A table summarizing the 

available technical information for each method can be found at the link below. The EPA strongly 

encourages the submission of additional supporting field and laboratory data as well as comments 

in regard to these methods. 

Problem Statement: Substitute Toluene for Methylene Chloride as the organic rinse 

 solvent 

Arguments to Support Actions Taken:

The use of a solvent for recovery of a “chemical compound” is predicated on knowledge of 

the chemical structure and characteristics of that compound. A chemist uses theory and 

experience to select the solvent that is most suited for a reaction system. The simple rule for 
solvents and reagents is that “like dissolves like” – a non-polar reactant will dissolve in a 

non-polar solvent; a polar reactant dissolves in a polar solvent. The polarity of a solvent is 

determined by its dipole moment (measure of charge distribution in a molecule), dielectric 

constant (DeC; distance between the internal charges in a molecule) and its miscibility with 

water. 

Water is a highly polar compound (owing to the large charge differential between the oxygen 

and hydrogen atoms in the molecule; DeC of 80) and will mix/dissolve high polarity 

compounds such as alcohol. There are other high polarity compounds such as acetone that 

have a high DeC value owing to the carbonyl (carbon-oxygen double bond; C=O) structure in 

the molecule. Hexane has a low DeC of 2.02 (dipole moment is 0.0) and is very non-polar. 

Toluene has a dipole moment of 0.36 so it is relatively non polar. Water (polar) and hexane 

(non-polar) are not-like compounds and are not miscible (oil and water don’t mix). 

Methylene chloride (MeCl2) has a DeC of 9.08 and is a relatively non-polar solvent that is 

not miscible in water. 

There are a number of aliphatic and aromatic organic compounds that may potentially be 

present in combustion effluents (alkanes – Cn-H2n; ketones – RR’C=O; aldehydes – RCOH; phenols – Rn-C6H5-n-OH). There is an unknown mixture of these compounds in the 

organic fraction of the OTM28 sample train. Method OTM28 includes MeCl2 as the rinse 

solvent for cleaning the glassware used in the sampling system as described below. 

“8.5.4 Sample Recovery. 

8.5.4.1 Recovery of Filterable Particulate Matter. Recovery of 

filterable particulate matter involves the quantitative transfer 

of particles according to the filterable particulate sampling 

method (i.e., Method 5, 17 or 201A). 

8.5.4.2 CPM Container #1, Aqueous Liquid Impinger Contents. 

Quantitatively transfer liquid from the dropout and the impinger 

prior to the CPM filter into a clean sample bottle (glass or 

plastic). Rinse the probe extension, condenser, each impinger and 

the connecting glassware, and the front half of the CPM filter 

housing twice with water. Recover the rinse water, and add it to 

the same sample bottle. Mark the liquid level on the bottle. CPM 

Container #1 holds the water soluble CPM captured in the 

impingers. 

8.5.4.3 CPM Container #2, Organic Rinses. Follow the water rinses 

of the probe extension, condenser, each impinger and all of the 

connecting glassware and front half of the CPM filter with an 

acetone rinse. Then repeat the entire procedure 

with two rinses of MeCl

2

, and save both solvents in a separate 

glass container identified as CPM Container #2. Mark the liquid 

level on the jar.”

 . This solvent has a “middle of the road” polarity. It is possible that MeCl2 may not dissolve 

all organics that may cling to the sampling system glassware. 
The sampling trains were initially rinsed with water, followed by acetone and toluene. This 

sequence and nature of solvents actually provide a variety of polarities to assure all types of 

organics present on the glassware of the sampling train are recovered for the analysis of the 

OTM28 parameters. The initial water rinse removes aqueous drops adhering to the 

glassware. The high polarity acetone that follows is miscible with water dissolves the 

ketones, aldehydes and phenolic compounds. The toluene rinse dissolves the CnH2n 

compounds. This is an exhaustive cleaning of the glassware that exceeds the simple rinse 

with MeCl2 may miss some of the oragnics targeted by OTM28.