Waters Sep-Pak XPoSure Aldehyde Sampler - Manual (Page 10)

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In the above example, only a single carbonyl source was present.
Under many test conditions more than one carbonyl source may be
present in significant concentrations. These other compounds will
consume DNPH, effectively reducing the capacity of the sampler for
the compound of interest. To assure that the capacity of the sampler
has not been exceeded, compare the DNPH peak areas of the sample
to a similarly eluted blank. The DNPH peak area in all samples
must be no less than 50% of the DNPH peak area of the blank. This
ensures the sampler capacity has not been exceeded.
d. Appendix D: Useful Conversion Factors
This appendix contains:
■ ■
Carbonyl to hydrazone conversion factors
■ ■
Equation for converting µg/L to ppmv
■ ■
Conversion factors: µg/L  ppmv
Obtaining carbonyl concentrations in eluates and air samples
required the use of several constants and conversion factors. The
factors described in this appendix can be used when converting
carbonyl weights to:
■ ■
Equivalent derivative weights for preparing standard
solutions
■ ■
Volumes for reporting air samples in ppmv
d.1. Carbonyl to Hydrazone Conversion Factors
Table 8 lists the molecular weights (MW) for some carbonyl
compounds. These values were used to derive the conversion
factors listed in Table 9. Multiply the carbonyl or derivative
weights by the appropriate factor for the desired conversion.
Table 8: Carbonyl and Hydrazone Molecular Weights
Carbonyl
Compounds Carbonyl Compounds
Molecular Weight, (MW
C
)
Hydrazone Derivative
Molecular Weight (MW
D
)
Formaldehyde 30.03 210.15
Adetaldehyde 44.05 224.17
Adetone 58.08 238.20
Glutaraldehyde 100.12 460.36
Table 9: Conversion Factors,
Carbonyl Weights
↔ Derivative Weights
Carbonyl
Compounds Carbonyl → Derivative,
(MW
D
/MW
C
)
Derivative → Carbonyl,
(MW
C
/MW
D
)
Formaldehyde 6.998 0.1429
Adetaldehyde 5.089 0.1965
Adetone 4.101 0.2438
Glutaraldehyde 4.589 0.2175
d.2. Equation for converting µg/L to ppmv
Carbonyl concentrations can be converted from µg/L to ppmv
(µL/L) by using the following expression:
(Result in ppmv) = (Result in µg/L) x 22.41 x T2 x P1
MWC T1 P2
Where values are:
22.41 = Molar volume of an ideal gas at STP (273.15 °K and
1 atm), L/mole
MWC = Molecular weight of carbonyl, g/mole
T1 = Standard temperature, 273.15 °K
T2 = Air sample temperature, ºK
P1 = Standard pressure, 1 atm
P2 = Air sample pressure, atm
d.3. Conversion Factors: µg/L to ppmv
Table 10 lists the factors for converting between µg/L and ppmv at
25 °C and 1 atm. Results are converted between µg/L (or mg/m
3 )
and ppmv, by multiplying by the appropriate factor.
Table 7: Breakthrough Example HPLC Results
Sampler
Amount
(µg)
Quantity Captured
Sampler – blank (µg)
Percent Captured
on Sampler
Sampler 1 75.06 75.00 91.8
Sampler 2 6.72 6.66 8.2
Blank 0.06 - -
Table 10: Factors for Converting Between µg/L and ppmv at
25 °C and 1 atm.
Carbonyl
Compounds
ppmv → µg/L µg/L p → ppmv
Formaldehyde 1.23 0.813
Adetaldehyde 1.80 0.555
Adetone 2.38 0.420
Glutaraldehyde 4.09 0.244
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Sep-Pak XPoSure Aldehyde Sampler