AOAC Final Action Methods in 2018

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.,

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 )

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

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