Waters Sep-Pak XPoSure Aldehyde Sampler - Manual (Page 6)

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d. Calculating Results
To calculate the aldehyde concentration in air:
1. Prepare a calibration line of peak area to standard
concentration on µg/mL of analyte as carbonyl compound.
2. Use the calibration line to determine the analyte concentration
in the blank and sample eluates.
3. Determine the mass of each analyte in the blank (W
b
) in
µg. This is done by multiplying each analyte concentration
by the eluate volume in mL. Compare these vales to the
specifications listed in Table 3. If these values are higher than
the specifications, contamination occurred during sample
preparation or storage.
4. Determine the mass of each analyte in the sample (W
s
) in µg.
This is done by multiplying each analyte concentration by the
eluate volume in mL.
5. Calculate the analyte concentration (C) in µg/L*. This is done
by dividing the weight of the analyte in the air (Ws-Wb) by the
volume of the air sampled (V) in liters.
C = W
s
– W
b
V
*The units, µg/L, is equivalent to mg/m 3 . For converting µg/L to ppmv at 1 atm
and 20 °C, see Appendix D.
IV. AP PLICATION EXAMPLES
a. Formaldehyde in Laboratory Air - STEL
The sample in Figure 6 was collected in a chemical research
laboratory using a portable sampling pump. The 22.5 liter air
sample was collected at 1.5 L/min. The chromatogram shows
0.02 ppmv formaldehyde, with trace levels of both acetonitrile
and acetone detected.
Figure 8. Analysis of Formaldehyde in Lab Air.
b. Glutaraldehyde in Laboratory Air – STEL
The sample in Figure 7 was collected in chemical research
laboratory using a portable sampling pump. The 22.5 liter air
sample was collected at 1.5 L/min. The chromatogram shows
0.02 ppmv of glutaraldehyde. Under these chromatographic
conditions the DNPH-glutaraldehyde diastereomers are resolved.
Figure 7. Analysis of Glutaraldehyde in Lab Air.
V. STORAGE AND DISPOSAL OF T HE SAMPLERS
a. Storing unused samplers
Always store any unused Waters Sep-Pak XPoSure Aldehyde
Samplers in their protective pouches to prevent contamination.
Store the sealed pouches in a refrigerator at (4 °C ± 2 °C) for up to
six months. Cartridges may be stored in their unopened pouches at
room temperature (20 to 25 °C) for up to two weeks.
Background levels of hydrazone derivatives increase slightly with
time and temperature. Before using cartridges exposed to high
temperatures or stored longer than the recommended periods, run
a blank.
b. Storing exposed samplers
Once a sampler has been used for collection, be careful to cap
and seal it until it is time to elute it. Inadvertent exposure of an
exposed cartridge can ruin a carefully collected sample. Elute
the derivatives from the cartridge within two weeks. The sample
eluates are stable at 4 °C ± 2 °C for up to one month.
c. Disposing of used cartridges
Dispose of used cartridges according to applicable government
regulations.
1. DNPH
2. DNPH-Formaldehyde
3. DNPH-Acetaldehyde
4. DNPH-Acetone
1. DNPH
2. DNPH-Formaldehyde
3. DNPH-Acetaldehyde
4. DNPH-Acetone
0 2 4 6 8 10 12 14
0
.002
.004
3
1
2
4
0 2 4 6 8
0
.002
.004
1
2a
0 2 4 6 8
0
.002
.004
1
2a
2b
1. DNPH
2a & 2b. DNPH-Glutaraldehyde Diastereomers
6
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Sep-Pak XPoSure Aldehyde Sampler