DISCUSSION - SR99

Table 4. Comparison of average and standard deviation of concentrations (mg/kg)

Table 6. Comparison of collocated samples collected with a 10-mL syringe vs. 5-g En Core sampler

SR99_05
Page Navigation
13

Table 5. Average and standard deviations (n = 5) of analyte con-

centrations (g/kg) for samples stored in the En Core sampler

after various holding periods under different storage conditions.

Analyte concentrations were established based on a moist soil

basis, and average weight of 5.1 g.

D7*

D14†

4 & 12C

*Stored for 7 days; 2 days at 42C and 5 days at 123C.

†Stored for 14 days; 2 days at 42C and 12 days at 123C.

**Values with common letter are not significantly different at the 95% confidence

interval (ANOVA and Fisher's Protected LSD).

††Percent recovery relative to D0 analyte concentration.

Overall, these findings parallel the results of the

1998b). The third observation suggests the biologi-

laboratory experiment performed with the En

cal degradation can be slowed down and perhaps

prevented by storing a sample at 12 3C. In this

Core sampler.

Table 10 contains the results for analyte stabil-

experiment, while large decreases (40% or greater)

ity in VOA vials with and without a punctured

in Ben, Tol, E-Ben, p-Xyl, and CDCE concentra-

septum. VOA vials without punctured septa

tions occurred after four or five days of storage at

4 2C, much smaller losses, if at all, were seen

showed no apparent change in analyte concentra-

tion over a 21-day storage period. However, all of

after transferring to a freezer and holding for nine

the analytes in a MeOH/soil slurry held in VOA

more days.

vials with punctured septa showed a continuous

The results of the final experiment of the empty

decrease in concentration with time. The rate of

VOA vial were also evaluated using a one-way

analyte loss from the VOA vials with punctured

analysis of variance (ANOVA) and least signifi-

septa appears to be around 5 to 10% per week of

cance difference tests (Fisher's Protected Least Sig-

storage.

nificant Difference), at the 95% confidence level

(Table 9). This evaluation showed that during re-

frigerated storage there was a slow continuous

decrease in all of the aromatic hydrocarbons, with

DISCUSSION

the possible exception of o-Xyl, and a fairly con-

Before the third update of SW-846, the majority

tinuous loss of TDCE and CDCE. However, once

of soil samples collected for characterization of

placed in the freezer, losses were abated even

VOC contamination followed procedures recom-

though storage was extended for another 12 days.

Index

Privacy Statement
Press Release
Contact