Figure 6. Correlation of P450RGS and EROD assays on 15 crude miscellaneous sediment extracts

Technical Note DOER-C8

July 1999

(Means of six replicates SD)

Time and Cost Comparisons. The P450RGS assay was less expensive than the EROD assay

for testing the same number of samples. The cost of testing is reduced considerably when more

samples are run at the same time. The P450RGS has significant advantages over the EROD assay

in terms of the ease of performance and the time required for completion of the assay. Protein

determination is not required for the P450RGS assay, and a much simpler instrument is used in the

quantitation (i.e., a luminometer rather than a spectrofluorometer). The stronger signal produced

by bioluminescence as compared with fluorescence increases the sensitivity of the P450RGS assay.

The breakdown of cost and time requirements for the assays is shown in Table 2 below.

Table 2

Time and Materials Comparison of the P450RGS and EROD Assays

Expense Item*

P450RGS

EROD

Cost of supplies, $**

4.5

11.0

Labor time, hr

Yes

Protein determination

* Time and the cost of materials based on testing two samples of six replicates each.

** Direct costs only.

To the nearest one-fourth hour.