SAMPLING, CLEAN-UP AND SEPARATION 

A Simplified Sample Train for Collection of Chlorinated 

Dibenzo-p-dioxins and Dibenzofurans from Incinerator 

Gaseous Emissions 

Les Lamparski1

, Terry Nestrick0, James Dunn2

1

Dow Chemical Co., Analytical Sciences Laboratory, Midland MI, USA 2

Dow Chemical Co. Toxicology and Environmental Research, Midland MI USA 

 

ORGANOHALOGEN COMPOUNDS Volume 66 (2004) 9

Introduction

Currently available sample collection methods for determination of the emissions 

of chlorinated dibenzo-p-dioxins and dibenzofurans (CDD/CDFs) from 

incineration devices predominately focus upon the measurement of these analytes 

for compliance purposes. As such, the usual methods of sample collection conform 

to the requirements defined by various government agencies. For example, in the 

United States, EPA Method 23a [1] is required for all compliance measurements. 

European analyses may be predicated upon the procedures defined in the VDI 

3499-2 [2] or the subsequent EN1948-1 [3]. The common feature for all of these 

methods is that the sample collection time is relatively long, 4-6 hours. Recently, 

procedures have been described for the long-term monitoring of stack emissions 

through the use of continuous on-line samplers [4-6]. All of the previous methods 

are useful for monitoring long-term (many hours) emission trends; but in 

examining the short-term variations in incinerator operation, information may be 

lost. In studies to improve incinerator operation, it is frequently necessary to 

measure the effects of operational upsets that may range from 15 minutes to 1 hour 

in duration. 

Over the period of the last 8 years, the number of analyses of stack gas emissions 

samples collected for the measurement of CDD/CDFs that have been undertaken at 

The Dow Chemical Company has increased dramatically, primarily because of 

company-initiated emission reduction projects. These initiatives have resulted in 

an increase in the number of sample analysis requests from approximately 10-20 
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ORGANOHALOGEN COMPOUNDS Volume 66 (2004) 10 

per year in 1995 to ~150 per year in 2002 and 2003. EPA –defined sampling 

procedures are required to demonstrate compliance with emissions regulations. 

Because of the complexity of the sample collection procedures for stack gas 

emissions samples and the limited resources available to meet the ever-increasing 

sample analysis demands, steps were initiated by Dow Analytical Sciences Lab to 

reduce the complexity of EPA-defined procedures [1] while not adversely 

affecting data quality of analytical results. The modified stack gas collection train 

has been in use for the collection of data to document process improvements 

undertaken to reduce dioxin emissions from incinerators. This document is 

intended to 1) describe a simplified stack gas sample collection train which has 

been used for a number of years at The Dow Chemical Company for the collection 

of research samples of gaseous emissions from incinerators; 2) explain the 

procedural differences compared to standard methods; 3) compare data generated 

by the techniques; and 4) discuss any potential biases in samples collected by this 

method. 

Materials and Methods

Figure 1 shown on the following page illustrates the differences between the EPA 

Method 23a (1a) sample train and the Dow SSS (1b) sample collection train. Basic 

changes incorporated in the SSS train are: 

• Replacement of the heated sample probe with an unheated probe. 

• Elimination of the “hot box” to contain the heated filter and associated 

connecting glassware. 

• Elimination of the quartz-fiber filter. 

• Elimination of the condenser to cool the heated gases exiting the “hot box”. 

• Connection of the gaseous and particulate effluent directly to the XAD-trap to 

utilize the absorptive properties of the XAD to capture CDD/CDFs from both 

vapor phase and condensed liquid phase and to filter the particulates from the 

gas phase. 

• The original design incorporated collection of the condensate after XAD and 

extraction for possible CDD/CDFs that may have passed through the XAD. 

Subsequent testing showed that >98% of CDD/CDFs were collected on the 

XAD, and this condensate trap was eliminated. 

• All gas measuring parameters necessary to insure correct measurement of the 

dry gas volume and collection of isokinetic samples remain the same in both 

trains. 
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ORGANOHALOGEN COMPOUNDS Volume 66 (2004) 11 

• Because of the shorter sample collection time, the SSS collection is done on a 

single traverse only rather than two perpendicular traverses for the Method 23. 

• Shipment of the entire sample train to analytical laboratory and rinsing and 

extraction of all components with benzene to remove CDD/CDFs from the 

interior of the train. Rather than rinsing and brushing with solvent in the field. 

 

Discussion

As summarized above, one of the main driving forces for the development of a 

simplified stack gas sampling train was to decrease the amount of time (and hence, 

expense) associated with the actual collection of emissions samples from waste 

incinerators. There were, however, other significant reasons for modifying the 

sample collection process: 

• Reducing the number of glassware pieces in the train resulted in lower 

logistical costs of maintaining an inventory of train components, cleaning 

parts between uses, and shipping costs. Fewer glass connections in Dow 

SSS train reduced the likelihood of leaks detected during the pre-test and 

post-test leak checks. Leak test failures can result in invalidation of a test 

sample and the need to repeat a test. 

• The shorter sample collection time of one hour compared to the four hour 

sample time could allow multiple data points to be collected in the same 

amount of time if there were a need to assess the short-term (hourly) 

variability of a unit. Short-term emission level variations, which are not 

readily detectable when averaged over a four-hour period, may be more 

easily detectable by means of the shorter sample collection cycle of the 

simplified stack gas sampling train. 

• The use of the Teflon® filter holder for the trapping of particulates in the 

hot box may also adsorb CDD/CDFs from the vapor phase. This 

phenomenon may affect the analyte concentrations in an unknown manner. 

Under some circumstances the Teflon® may absorb CDD/CDFs from the 

gas phase and bias results low. Generally, the ratio of the absorbed analyte 

to the total amount in the gaseous phase is small and may not significantly 

reduce analyte concentrations for any single sample [7]. Under other 

circumstances, previously absorbed CDD/CDFs from a higher 

concentration sample may desorb the analytes and bias a relatively clean 

sample higher than normal [8]. 

• The approach of reducing the amount of heated glassware was predicated 

on the concept that reactive gases in the effluent could change the 
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ORGANOHALOGEN COMPOUNDS Volume 66 (2004) 12 

composition of the analytes as they are trapped on a heated filter for up to 

four hours. Generally, this is not a problem with emission samples that 

have been purified through an efficient Air Pollution Control Train; but in 

some of our initial incinerator improvement studies, we wished to evaluate 

the CDD/CDF content in gases before the acid absorbing towers. These 

samples contained significant levels of chlorine and hydrochloric acid, 

which would have adversely affected the measured CDD/CDF 

concentrations. The ability to accurately measure the CDD/CDF content of 

gaseous emissions upstream of the air pollution control system was 

instrumental in isolating process conditions that could be responsible for 

the formation or emission of CDD/CDFs. 

Data illustrating the quantitative comparison of the two sample collection trains 

are shown in Table 1 below. In these experiments, specific incinerator effluent 

samples were simultaneously collected using the different sample trains. Since the 

normal collection times that were employed for the two trains were not identical 

(four hours vs. one hour), absolute comparison is not possible. In most cases there 

is good agreement between the SSS and the Method 23a (M23a) for TEQ, 

generally within ~20%. 

One sample from Unit#5 shows both TEQ and total CDD/CDFs levels that are 

about twice as high for the SSS sample. Possible explanations for this difference 

are: the possible reaction of CDD/CDFs adsorbed on trapped particles reacting 

with reactive chemicals in the effluent in the M23a train while being retained on 

the heated filter for the extended sampling period; or a short-term upset condition 

that was occurred during the time when both the M23 and the SSS were being 

collected. The incinerator returned to normal operation and the higher emission 

level was average down in the M23 sample. 

Another obvious sample difference is exemplified in the data shown for the sample 

Unit#4. This unit was part of the Magnesium Production operation and not a true 

incinerator. This unit consisted of two furnaces that recycled chlorine between 

them for the production of magnesium chloride. The gas that was collected was the 

recycle gas between the units and not true stack gas emission, but the information 

is included here to illustrate the point that there could be significant differences 

between samples collected by the M23a train and the SSS train. It has been 

surmised that the heated portions of the sample train provided an environment that 

was conducive to the reaction of adsorbed dioxins on the filtered particulates with 
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ORGANOHALOGEN COMPOUNDS Volume 66 (2004) 13 

chlorine in the gas phase and may have resulted in the actual loss of analyte 

through degradation of CDD/CDFs from the sample. 

The comparison for total CDD/CDFs shows a slightly greater amount of variation 

than for the TEQ; but it is important to point out that in every case except one 

(Unit#1) both the total and TEQ values reported for the SSS are higher than the 

M23 results. Possible explanations include: 

1) The M23a collection is not as efficient as the SSS train and some analyte is 

lost by passing through the M23a train. 

2) Larger air leaks in the M23a train due to the greater number of, and stress on, 

glass connections have biased the sample volumes high and, hence, the 

analyte concentrations low. 

3) The SSS-train is inherently more efficient at trapping the CDD/CDFs because 

they enter the XAD trap in both the gaseous and aqueous phase rather than 

totally in the condensed aqueous phase. 

4) Poor recovery of analytes in the M23a due to inefficient elution/rinsing from 

the many glass pieces of the M23a train. 

5) Reaction of CDD/CDFs on the heated components of the M23a train. 

6) The SSS-train is biased high because CDD/CDFs are produced under certain 

conditions on the SSS train. 

Definitive explanation of the causes of the differences in analyte concentrations is 

beyond the scope of this report and could be the subject of a more extensive 

collaborative research project. However, regardless of the reason for the 

differences, the results obtained from samples collected with SSS train: 1) do not 

underestimate the CDD/CDF concentrations relative to the Method 23a train; 2) 

may, under some conditions, be more accurate than Method 23a; 3) are usually 

within commonly accepted “experimental error” (±25%) for these types of 

measurements. 
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ORGANOHALOGEN COMPOUNDS Volume 66 (2004) 14 

Table 1: Quantitative Comparison of Method 23 and Dow SSS Sampling Trains 

Conclusion

The productivity enhancements that are discussed have reduced the cost of sample 

collection for stack gas emissions samples by more than ~70% based on previous 

experience using EPA Method 23 methodology. This reduction came by 

implementing a shorter sample collection time, which allowed a much greater 

number of samples to be collected in an 8-hour workday and a greatly reduced 

amount of collection train glassware. Five SSS trains could be collected in an 8-

hour workday, but only one Method 23a sample could be collected in 

approximately 6 hours. This allows many more samples to be collected for use in 

process control or process improvement studies. The less complicated (fewer 

glassware pieces) sample collection train: 1) reduced the amount of glassware 

precleaning; 2) reduced the possibility of collection train leaks, before and after 

sampling; and 3) eliminated the need for the particulate filter in the sample train. 

Analysis of the impinger water collected after passage through the XAD-trap 

demonstrated that ~98% of the CDD/CDFs are removed on the XAD-trap in the 

improved configuration, by acting as a vapor and liquid absorbent, that is 

employed for the SSS train. 

Inherent problems with the heated particulate filter and sample probe include the 

possibility of reactive gases (e.g. Cl2, HCl) in the sample reacting with compounds 

adsorbed on the trapped particulates and changing analyte concentrations. 

Hazardous waste incinerators burning chlorinated wastes have the possibility 

M 2 3 S S R ela tive

TTU D ate T otal TEQ T o ta l TEQ TEQ

U n it# 1 0 6 /1 2/95 19 8 .1 3 .1 2 1 5 6.1 3.14 1 01 %

U n it# 1 0 6 /1 3/95 15 0 .4 3 1 6 0.3 3.07 1 02 %

U n it# 2 0 6 /1 3/95 60 .9 7 0 .8 3 8 4 .3 6 0.84 1 01 %

U n it# 2 0 6 /1 4/95 71 .9 7 0 .7 7 8 9 .3 3 0.77 1 00 %

U n it# 3 0 8 /0 3/95 17 8 .8 3 .0 5 2 4 6 3.83 1 26 %

211.1 3.47 114%

U n it# 4 0 8 /0 5/95 6 .8 3 0 .1 8 1 0 0 3 .7 20 5 6%

U n it# 5 0 8 /0 3/95 19 3 .2 1 .9 3 4 0 7.4 3.54 1 83 %

08/03/95 156.6 1.61 195.2 1.74 108%
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ORGANOHALOGEN COMPOUNDS Volume 66 (2004) 15 

under extreme conditions or equipment failure of emitting small amounts of HCl 

or Cl2 in the gaseous effluent. Normally, these compounds are efficiently removed 

in the Air Pollution Control System; but occasionally, these components may fail. 

The reaction of CDD/CDFs with these active gases will change the characteristics 

of the resulting analytes in an unknown manner. Elimination of the heated portion 

of the sample train was intended to reduce this possibility. 

In summary, the information presented above supports the use of this simplified 

stack gas collection train for the measurement in CDD/CDFs the gaseous effluent 

from hazardous waste incinerators operating under a variety of process conditions. 

Data obtained can certainly be used for process optimization, trouble-shooting, and 

some emissions estimates. With appropriate validation, we feel that this could also 

be a cost-effective alternative to Method 23a for the collection of samples for 

compliance monitoring. 

References:

[1] U.S. Environmental Protection Agency Method 23a, Revision #1 – 

Determination of Polychlorinated Dibenzo-p-dioxins and Polychlorinated 

Dibenzofurans from Stationary Sources, USEPA Office of Solid Waste, SW-846, 

December 1996. 

[2] VDI (Verein Deutscher Ingenieure) 3499-2, Emission Measurement – 

Determination of Polychlorinated Dibenzo-p-dioxins (PCDD) and Dibenzofurans 

(PCDF) – Filter/condenser Method, 1993 (draft). 

[3] EN (European Standard) 1948-1, Stationary Source Emissions, Determination 

of the Mass Concentration of PCDDs/PCDFs Part 1: Sampling, CEN, 1996. 

[4] K. Mohr, T. Ludwig, Ch. Brockmann, H. Grund, H. Ortner, P. Hoffmann, J. 

Jager,”Modified Continuous Sampling and Clean-up Device for the Determination 

of PCDD/F in Waste Gases of Incinerators and Thermal Processes,” Chemosphere

1999, Vol.39, No.11, 1937-1950. 

[5] T. Ludwig, “First Long-Term Field Test of the PCDD/F-Analyzer DioxinCop,” 

Organohalogen Compounds, 2003, Vol. 60-65, presented at Dioxin 2003, Boston, 

MA USA. 

[6] F. Idczak, S. Petitjean, P. Duchateau, L. Bertrand, “Validation and 

Optimization of Continuous Sampling to Monitor PCDDs and PCDFs Emissions 

of Waste Incinerators,” Organohalogen Compounds, 2003, Vol. 60-65, presented 

at Dioxin 2003, Boston, MA USA. 
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ORGANOHALOGEN COMPOUNDS Volume 66 (2004) 16 

[7] S. Kreisz, H. Hunsinger, H. Vogg,, “Technical Plastics as PCDD/F Absorbers,” 

Organohalogen Compounds, 1995, Vol. 23, presented at Dioxin 1995, Edmonton, 

AB Canada. 

[8] M. Wilken, personal communication, 02 March 2004. 
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