Method Comparability Data for EPA

10/18/2010

Tyler Martin

Orono Spectral Solutions, inc.

tyler.martin@ossmaine.com

Three different data sets are provided.

1. Triplicate data for samples tested at an independent laboratory for both D7575 and 1664 results

2. Single-replicate data for samples tested by D7575 at OSS and at an independent lab for 1664, for sam 

3. Single-replicate data for samples tested by D7575 at OSS and at an independent lab for 1664, for sam 

In all cases samples were preserved in the standard manner, i.e. acidified to pH 2 and kept cool to 4 C or 

resulted in the samples from Sets 2 and 3 warming up for a period of time in two separate events, one la 

and a third event in which the samples were frozen. It is unknown precisely how this may have affected 

as samples were tested by both methods within a relatively short time frame of 10 days or less between 

Set 1 was not affected by these issues.

Set 1

Samples tested in triplicate at an independent laboratory

Matrix 1664 Result (mg/L) D7575 Result (mg/L)

Bilge Water (Sea) 39.1 41.0

Bilge Water (Sea) 37.5 42.2

Bilge Water (Sea) 35.6 44.9

Peanut 38.4 38.0

Peanut 35.6 37.0

Peanut 38.8 36.5

Lunchmeat 30.3 37.2

Lunchmeat 28.9 33.1

Lunchmeat 29.6 39.4

Set 2

Samples test by OSS for D7575 and an independent lab for 1664, testing completed within or very close 

note that repeated matrices are different samples from the same or different locations

Matrix 1664 Result (mg/L) D7575 Result (mg/L)

Restaurant (dilution) 250.0 284.0
Restaurant (dilution) 310.0 313.0

Restaurant (dilution) 450.0 491.0

Car Wash 12.0 8.0

Car Wash 26.0 24.0

*Dilution was used to get the D7575 number. The standard upper limit for D7575 is 200 mg/L, but highe 

Set 3

Samples test by OSS for D7575 and an independent lab for 1664, testing completed beyond to the samp 

We believe old samples are useful for such testing, even though they would not be useful for regulatory 

Both methods were performed on the sample within 10 days of each other.

For clarity, only matrix types not included in the validation studies or the triplicate independent testing i 

Matrix 1664 Result (mg/L) D7575 Result (mg/L)

Restaurant 19 22

Restaurant (out of range - D7575 340

Industrial Laundry 140 79

Aluminum Can Manufacturer 56 55
ples which were within or very close to the holding time when tested.

ples which were beyond the holding time when tested.

r below. However, unfortunate equipment (cooler) issues

asting one week and the second lasting approximately two weeks, 

d the samples, but 

n tests, we believe the results are useful.

to the sample holding time proscribed by 1664 and D7575 (28 days)

*Dilution
*Dilution

*Dilution

er levels can be determined through dilution. In these cases, the standard method was performed and the resul 

ple holding time proscribed by 1664 and D7575, sometimes significantly beyond (a year or more).

y purposes, but the results must be examined with this time factor in mind, and results considered less reliable th 

in Set 1 above are included in this set.

*sample was correctly found to be out of range, but was not diluted and re-tested by D7575 due to a 

t was over 200 mg/L, so a 5x dilution was performed and tested by D7575

han those above.

an oversight
0.0

100.0

200.0

300.0

400.0

500.0

600.0

1664 Result (mg/L)

D7575 Result (mg/L)
1.0

10.0

100.0

1000.0

1664 Result (mg/L)

D7575 Result (mg/L)