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Table 2014.08I. PAH analytes and corresponding
13
C-PAHs
used for PAH signal normalization
Analyte
13
C-PAH used for signal normalization
Anthracene
Anthracene (
13
C
6
)
Benz[
a
]anthracene
Benz[
a
]anthracene (
13
C
6
)
Benzo[
a
]pyrene
Benzo[
a
]pyrene (
13
C
4
)
Benzo[
b
]fluoranthene
Benzo[
b
]fluoranthene (
13
C
6
)
Benzo[
g,h,i
]perylene
Benzo[
g,h,i
]perylene (
13
C
12
)
Benzo[
k
]fluoranthene
Benzo[
k
]fluoranthene (
13
C
6
)
Chrysene
Chrysene (
13
C
6
)
Dibenz[
a,h
]anthracene
Dibenz[
a,h
]anthracene (
13
C
6
)
Fluoranthene
Fluoranthene (
13
C
6
)
Fluorene
Fluorene (
13
C
6
)
Indeno[1,2,3-
cd
]pyrene
Indeno[1,2,3-
cd
]pyrene (
13
C
6
)
Naphthalene
Naphthalene (
13
C
6
)
Phenanthrene
Phenanthrene (
13
C
6
)
Pyrene
Pyrene (
13
C
6
)
1-Methylnaphthalene
Naphthalene (
13
C
6
)
2,6-Dimethylnaphthalene
Phenanthrene (
13
C
6
)
1-Methylphenanthrene
Phenanthrene (
13
C
6
)
1,7-Dimethylphenanthrene
Phenanthrene (
13
C
6
)
3-Methylchrysene
Chrysene (
13
C
6
)
where
c
13C-PAH
is the concentration of the corresponding
13
C-PAH in
the calibration standard solutions (in µg/L);
X
13C-PAH
is the amount
of the corresponding
13
C-PAH added to the sample (in ng); and
m
is the sample weight (in g). Based on the method procedure and
preparation of the calibration standard solutions,
c
13C-PAH
is 50 µg/L,
X
13C-PAH
is 50 ng, and
m
for the test samples is 10 g.
In the collaborative study, eight concentration levels were used
for the calibration, corresponding to 5, 10, 20, 50, 100, 200, 500,
and 1000 µg/L for benzo[
a
]pyrene and other lower-level PAHs, to
12.5, 25, 50, 125, 250, 500, 1250, and 2500 µg/L for higher-level
PAHs, except for naphthalene that was present at 25, 50, 100, 250,
500, 1000, 2500, and 5000 µg/L. Coefficients of determination (r
2
)
should be 0.990 or greater and back-calculated concentrations of
the calibration standards should not exceed ±20% of theoretical. For
lower concentration levels, a limited calibration curve (without the
higher-end concentration points) may be used for better accuracy.
If a well-characterized quadratic relationship occurs, then a best-
fitted quadratic curve may be used for calibration. Otherwise, if
the back-calculated concentrations exceed ±20% of theoretical,
normalized signals of the nearest two calibration standards that
enclose the analyte signal in the sample can be used to interpolate
the analyte concentration in the final extract.
References: (1) Kalachova, K., Pulkrabova, J., Drabova, L.,
Cajka, T., Kocourek, V., & Hajslova, J. (2011)
Anal. Chim. Acta
707
, 84–91.
http://dx.doi.
org/10.1016/j.aca.2011.09.016
J. AOAC Int . 98 , 477 (2105)DOI: 10.5740/jaoacint.15-032
Posted: April 30, 2015
Candidates for 2016 Method of the Year
231