United States
Environmental Protection
Agency
Environmental Monitoring Systems
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S4-83-031 Aug. 1983
Project Summary
Laboratory Evaluation of an
Impinger Collection/Ion
Chromatographic Source Test
Method for Formaldehyde
E. Estes, P. Grohse, W. F. Gutknecht and R, K. M. Jayanty
An impinger collection/ion chro-
matographic source test method for
formaldehyde was developed and eval-
uated. An impinger solution of 3% hy-
drogen peroxide/0.025 N sodium hy-
droxide was used to oxidize known
amounts of formaldehyde to formate
ion, which is readily analyzed by ion
chromatography. After standing over-
night, samples were diluted 1:5 and
then analyzed on a Dionex Model 14
ion chromatograph having a standard
anion separator column, an anion sup-
pressor column, and a conductimetric
detector. Using 0.0025 M N^BitOy as
the eluent and mass transfer, by volatili-
zation, of para formaldehyde directly
into collection impingers as the formal-
dehyde-atmos phere generation tech-
nique, recoveries of 85 to 90 percent
were achieved.
Unlike colorimetric methods for form-
aldehyde, ion chromatography is not
subject to interference from phenol,
which is present with formaldehyde in
many source emissions. In addition,
interfererrt tests showed that the ion
chromatographic method is not sub-
ject to interference from trioxane, a
stable formaldehyde polymer, or from
hexamethylene tetramine, a frequent-
ly used source of formaldehyde in in-
dustrial processes.
This Project Summary was developed
by EPA's Environmental Monitoring
Systems Laboratory, Research Triangle
Park. NC, to announce key findings of
the research project that is fully docu-
mented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Formaldehyde has been linked to eye
and upper respiratory tract irritations,
headaches, drowsiness, and gastrointes-
tinal problems. In anticipation of the regu-
lation of formaldehyde by the U.S. Envi-
ronmental Protection Agency's Office of
Toxic Substances, this project was under-
taken to evaluate and standardize a source
test method for the chemical
Laboratory evaluation of a chromotropic
acid method for measuring formaldehyde
in the effluent of formaldehyde manu-
facturing plants was originally planned.
However, a literature review indicated that
this method is subject to interference from
phenol, which is present with formalde-
hyde in many source emissions. Laboratory
efforts were therefore concentrated on ion
chromatographic analysis, which is not
subject to phenol interference.
An absorbing solution of 3% hydrogen
peroxide/0.025 N sodium hydroxide (pH
9.2) was used to oxidize known amounts
of formaldehyde to formate ion, which is
readily analyzed by ion chromatography.
Samples were collected at 1 L/min using
two midget impingers in series, each con-
taining 20 mL of absorbing solution. After
standing overnight the two impingers
were combined and diluted 1:5 and then
analyzed on a Dionex Model 14 ion
chromatograph having a standard anion
separator column, an anion suppressor
column, and a conductimetric detector.
With 0.0025 M Na2B407 as the eluent
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the peroxide and formate peaks were well
separated, eliminating any analyses prob-
lems resulting from alkaline hydrogen
peroxide interference.
Three methods of generating atmos-
pheres of known concentrations of form-
aldehyde for sampling were evaluated.
The first method, a permeation system,
was unsatisfactory because the permea-
tion rate of the tube fluctuated, averaging
about twice the rate certified by the manu-
facturer. Th second approach, involving
volatilization of formaldehyde into a Teflon
bag, resulted in low recoveries, possibly
because of formaldehyde loss to the walls
of the bag (Teflon is a registered trade-
mark of E. I. du Pont de Nemours & Co.,
Wilmington, DE). The third approach,
which was the most effective, involved the
mass transfer, by volatilization, of para-
formaldehyde from a heated glass tube
directly into impingers containing the
absorbing solution (Figure 1).
Two compounds that potentially could
be oxidized to formate were tested as
possible interferents to the ion chro-
matographic method S-trioxane was tested
as an example of a stable formaldehyde
polymer. Hexamethylene tetramine, a fre-
quently used source of formaldehyde in
industrial processes, was also tested.
Samples of 20, 50, and 100 /ig/mL of
each were prepared by diluting stock solu-
tions in 3% H202/0.025 N NaOH. After
standing overnight, the samples were
diluted 1:5 before analysis on the ion
chromatograph.
Results
In a final series of tests, in which sam-
ples collected using the mass transfer
system were carefully observed to ensure
that the paraformaldehyde was complete-
ly volatilized, a mean recovery of 86.5
percent was achieved. Control samples
prepared by dissolving known quantities
of paraformaldehyde in the impinger solu-
tion yielded a mean recovery of 98 percent
Linear regression analysis was per-
formed to determine if the percent re-
covery was level-dependent The variation
of percent recovery with quantity of form-
aldehyde vaporized, 0.011 ± 0.003 per-
cent per microgram formaldehyde, was
small but significant at the 99 percent
confidence level. Sampling precision, also
obtained from the regression analysis,
ranged from 7 percent for the smallest
quantity of formaldehyde vaporized to 5
percent for the highest quantity. Thus,
there is evidence that recovery may be-
come less efficient at lower formaldehyde
concentrations. On the other hand, the
control samples gave excellent conver-
sions and recoveries so that the formalde-
hyde generation process may have been
the real problem. Geisling et al.* experi-
enced similar inconsistencies in generat-
ing formaldehyde from paraformaldehyde
and found that other compounds are re-
leased when this method is used. Con-
sequently, they developed a generation
system using vapor-phase depoly'meriza-
tion of trioxane, with reported conversions
to formaldehyde of essentially 100 percent
In the interferent tests, only small
formate peaks, possibly due to impurities,
were observed for trioxane and hexa-
methylene tetramine, indicating little or no
interference from these compounds.
Conclusions and
Recommendations
The impinger collection/ion chromato-
graphic source test method for formalde-
hyde was determined to be suitable for
field applications. A field test at a plant
with formaldehyde emissions is recom-
mended to verify the test method. In
future studies of the source test method,
depolymerization of trioxane is recom-
mended as the formaldehyde-generation
method.
•Geisling, K. L, Miksch, R. R., and Rappaport, S. M.
Generation of Dry Formaldehyde at Trace Levels by the
Vapor-Phase Depolymerization of Trioxane. AnaL Chera
54(1):140-42, 1982.
Heating Tape
Glass Tube
Zero Air,
1 L/min
Aluminum Sample
Boat Glass Ball Joint
Asbestos
Pad
Impinger containing 20 mL
3% HdOt/0.025 N NaOH
Figure 1. Formaldehyde-generation system:mass transfer.
2
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E. Estes. P. Grohse, W. F. Gutknecht, and R. K. M. Jayanty are with Research
Triangle Institute, Research Triangle Park, NC 27709.
Joseph E. Knoll is the EPA Project Officer (see below).
The complete report, entitled "Laboratory Evaluation of an Impinger Collection/Ion
Chromatographic Source Test Method for Formaldehyde,". (Order No. PB 83-
225 326; Cost: $8. SO, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
irU.S. GOVERNMENT PRINTING OFFICE 1983-659-017/7158
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Environmental Protection
Agency
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