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Carbonyl
Compounds by USEPA TO-11A |
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US EPA TO-11A is
the International Standard for the "Determination
of Aldehydes and Ketones in Ambient Air
using Active Sampling onto Absorbent Cartridges."
The method is validated for a wide range
of Carbonyls, down to trace levels <
0.1 ppbv in air.
Sampling is by DNPH Cartridge,
recognised as having many advantages over other
sampling methods.
Formaldehyde is a major compound
in the formation of photochemical ozone . Short
term exposure to formaldehyde and other specific
aldehydes (acetaldehyde, acrolein, 2-butenal)
is known to cause irritation of the eyes, skin,
and mucous membranes of the upper respiratory
tract . In polluted atmospheres, indoors as
well as outdoors, formaldehyde may contribute
to common annoyances such as eye irritation
and unpleasant odours.
Summary of Method
- A known volume of ambient air is drawn
through a prepacked cartridge coated with
acidified DNPH at a sampling rate of 100-2000
mL/min for an appropriate period of time.
The sampling volume is dependent on the
expected concentration in the test atmosphere
but typically ranges between 10 and 1000
litres.
After sampling, the sample cartridges
and field blanks are individually capped.
Sample identifying tags and labels are
then attached to the capped tubes. They
are then placed in a polypropylene shipping
container, cooled ( to ~ 4 deg C ), and
returned to the laboratory for analysis.
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DNPH sample cartridge
DNPH cartridge mounted
on sample air pump
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Based on collecting a 500 litre sample of air through
the cartridge and analysis to our standard detection
limit of 0.5 µg/cartridge, the detection
limit in air will be 1.0 µg/m3.
With certified media, analysis to 0.1 µg/cartridge
and collecting a 1000 litre sample, the detection
limit can be as low as 0.1 µg/m3.
The compounds listed below are reported in the
Standard Leeder Consulting Carbonyl Screen. Many
other compounds can also be analysed by this method.
These include Isovaleraldehyde, p-Tolualdehyde,
o-Tolualdehyde, Isobutyraldehyde, 2,5-Dimethylbenzaldehyde,
m-Tolualdehyde, 2-Pentanone, Furfural and Glutaraldehyde.
We also offer the option of analysis by HPLC-MS,
which can detect a number of additional compounds.
This option enables analysis of over 40 compounds
plus Mass Spectrometry confirmation
in one test.
Carbonyl
Compounds by DNPH Cartridge |
| Formaldehyde |
Propanal |
| Acetaldehyde |
Hexanal |
| Acetone |
Tolualdehyde |
| Acrolein |
Methacrolein |
| Benzaldehyde |
Pentanal |
| Butanal |
2-Butanone |
| 2-Butenal |
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Summary of the USEPA TO-11a Method for
the Determination of Aldehydes and Ketones in
Ambient Air using Active Sampling Onto Absorbent
Cartridges.
A known volume of ambient air is drawn
through a prepacked cartridge coated with acidified
DNPH at a accurately measured sampling flow rate
of between 1 litre and 2 litres per minute for
an appropriate period of time. The direction of
the sampling flow should be in the specified direction.
The sampling time and volume is dependent on the
expected concentration in the test atmosphere
but typically ranges between 10 litres and 1000
litres. The volume should be determined to avoid
sample breakthrough and the total carbonyls on
the tube should not exceed 75 ug.
After sampling, the sample cartridges and field
blanks should be individually capped. Sample identifying
tags and labels are then attached to the capped
cartridges which should be placed immediately
in the foil envelopes provided and placed in a
polypropylene shipping container, cooled ( to
~ 4 deg C ), protected from light, and returned
to the laboratory for analysis.
Care should be exercised in the handling of cartridges
to minimise unintentional exposure.
It should be noted that OZONE is a known negative
interference. If you suspect the presence of ozone,
use an ozone denuder or scrubber as detailed in
the method. With each batch of up to 10 samples,
at least one trip blank and an unused cartridge
for a laboratory blank should be included in the
batch sent to the laboratory. Samples should be
analysed within 30 days of sampling assuming they
have been properly
stored.
This Summary is purely for general information
and we advise you refer to the USEPA TO-11 method
for specific guidance. |
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