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Carbonyls are collected and measured from a vari-
ety of samples, including air, exhaust, and cigarette
smoke. For example, the California Air Resources
Board (CARB) was established in 1967 to address
many aspects of air pollution, including air quali-
ty problems caused by motor vehicles. CARB
Method 1004 is used by the automotive industry
to monitor a range of carbonyl compounds (e.g.,
aldehydes and ketones) in engine exhaust.
Sample collection cartridges impregnated with
2,4-dinitrophenylhydrazine (DNPH), or impingers
containing acidified DNPH, are used to sample air
or exhaust. After conversion to DNPH derivatives,
the carbonyl compounds are collected and analyzed
by HPLC. Since the DNPH derivatives absorb
strongly at 360nm, detection limits below 1ppm
are easily achievable. The original CARB method
uses two C18 columns in series for analysis,
although other columns can be used as long as they
provide an equivalent or better separation.
The new Allure® AK HPLC column was developed
specifically for the analysis of aldehydes and
ketones. With a single 200mm column, excellent
resolution of these compounds can be achieved in
less than 12 minutes (Figure 1). While C18 phases
often cannot separate butyraldehyde and methyl
ethyl ketone (MEK), the Allure® AK column shows
excellent resolution of this difficult pair. In addi-
tion, a simple mobile phase gradient of water:ace-
tonitrile can be used with the Allure® AK column,
while C18 phases require the addition of THF to
achieve acceptable resolution.
When analyzing aldehydes and ketones by HPLC,
such as the carbonyls specified in CARB method
1004, the new Allure® AK column will give you the
resolution and fast analysis times that you require.
•
12
•
2007 vol. 4
Industrial Hygeine
Complete Resolution of 13 Carbonyls as DNPH Derivatives
Using the New Allure® AK HPLC Column
By Randy Romesberg, HPLC Innovations Chemist, and Becky Wittrig, Ph.D, HPLC Product Marketing Manager
• Superior separation of difficult carbonyls—including butyraldehyde and methyl ethyl ketone—compared to
C18 columns.
• Allows the use of a simple water:acetonitrile mobile phase for easier preparation and waste disposal.
• Significantly faster run time than conventional C18 columns—less than 12 minutes.
Figure 1
Excellent resolution of carbonyl compounds in less than
12 minutes, using the Allure® AK HPLC column and a simple
water:acetonitrile mobile phase gradient.
Allure® AK Columns
Physical Characteristics:
cat. #
price
5µm Column, 3.2mm, 200mm (with Trident Inlet Fitting)
9159523-700
$552
5µm Column, 4.6mm, 200mm (with Trident Inlet Fitting)
9159525-700
$552
particle size: 5µm
pore size: 60Å
endcap: yes
pH range: 2.5 to 7.5
temperature limit: 80°C
LC_EV0393
Ret. Time
Peak
(min.)
DNPH derivatives of:
1. formaldehyde
4.74
2. acetaldehyde
5.78
3. acrolein
6.86
4. acetone
7.09
5. propionaldehyde
7.31
6. crotonaldehyde
8.19
7. methacrolein
8.55
8. butyraldehyde
8.79
9. methyl ethyl ketone
9.06
10. benzaldehyde
10.03
11. valeraldehyde
10.39
12.
m
-tolualdehyde
11.08
13. hexaldehyde
11.36
Sample:
Inj.:
10µL
Conc.:
3µg/mL each analyte, as
aldehyde/ketone
Sample diluent: acetonitrile
Column:
Allure
®
AK
Cat.#:
9159525-700
Dimensions:
200mm x 4.6mm
Particle size:
5µm
Pore size:
60Å
Conditions:
Mobile phase:
A) water : B) acetonitrile
Time (min.)
%B
0
60
8
70
10
100
Flow:
1.5mL/min.
Temp.:
30°C
Det.:
UV @ 360nm
acetaldehyde-2,4-DNPH
acetone-2,4-DNPH
acrolein-2,4-DNPH
benzaldehyde-2,4-DNPH
n
-butyraldehyde-2,4-DNPH
crotonaldehyde-2,4-DNPH
formaldehyde-2,4-DNPH
hexaldehyde-2,4-DNPH
methacrolein-2,4-DNPH
methyl ethyl ketone-2,4-DNPH
propionaldehyde-2,4-DNPH
m
-tolualdehyde-2,4-DNPH
valeraldehyde-2,4-DNPH
CARB 1004 Aldehyde/Ketone-DNPH Calibration
Standard
(13 components)
3µg/mL each in acetonitrile, 1mL/ampul
cat. # 33093
(ea.) $51
Guard Cartridge
qty.
cat. #
price
10 x 4.0mm
3-pk.
915950210
$135