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. Author manuscript; available in PMC: 2010 Apr 22.
Published in final edited form as: Environ Toxicol Chem. 2008 Nov;27(11):2224–2232. doi: 10.1897/07-660.1

Table 1.

Enzyme-linked immunosorbent assay (ELISA) cutoff value for the detection of toxic equivalents (TEQs) determined by gas chromatography/high-resolution mass spectrometry (GC-HRMS). The ELISA result is expressed in 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (TCDD)a

Detection of samples above 1,000 pg TEQ/g soil
GC-HRMS (pg TEQ/g)
ELISA (pg TCDD/g) >1,000 <1,000 Total
>100 (True +) 3 (False +) 2 5
<100 (False −) 0 (True −) 11 11
Total 3 13 16
Detection of samples above 250 pg TEQ/g soil
GC-HRMS (pg TEQ/g)
ELISA (pg TCDD/g) >250 <250 Total
>100 (True +) 5 (False +) 0 5
<100 (False −) 0 (True −) 11 11
Total 5 11 16
a

True positive: Samples higher than the defined GC-HRMS criteria that were correctly predicted by ELISA (ELISA result higher than 100 pg TCDD/g soil); true negative: Samples lower than the defined GC-HRMS criteria that were correctly predicted by ELISA (ELISA result lower than 100 pg TCDD/g soil); false negative: Samples higher than the defined GC-HRMS criteria that were incorrectly predicted by ELISA (ELISA result lower than 100 pg TCDD/g soil); false positive: Samples lower than the defined GC-HRMS criteria that were incorrectly predicted by ELISA (ELISA result higher than 100 pg TCDD/g soil).