that the difference between means for the discrete

samples resulted in a pink or orangish solution,

samples and composites observed for the field

denoting the presence of low levels of TNT. Only

results may be attributable to our using only

the extract from sample 7 needed to be diluted to

roughly equal weights of individual samples when

maintain the absorbance in the linear range after

preparing the composites here. However, this

reaction with the EnSys reagent.

should also have affected the laboratory results

Duplicate analyses for samples at this location

and clearly this was not the case.

appeared to be quite acceptable, with mean RSDs

of 16.7% for the on-site analyses, meaning that

Sampling location 3

field homogenization was adequate. Laboratory

On-site analytical results for sampling location

analyses for samples from this location were con-

3 are presented in Table 3a. At this location six of

sistently lower than corresponding field analy-

the seven samples had very low levels of TNT (2

ses. This was also true for the composite samples

5 g/g), but the seventh location had a much

and it shows a positive bias for the field TNT

higher TNT concentration (> 80 g/g). Because

method for these soils.

TNT concentrations were low, the acetone extracts

ANOVA and LSD tests were conducted for field

used for on-site analysis were run without dilu-

and lab data both with and without logarithmic

tion. Extracts had a straw-yellow color that re-

transformation (Table 3b). We obtained F ratios of

sulted in a significant background absorbance at

64.6 for on-site and 911 for the lab that were sig-

540 nm. Reaction with the EnSys reagent for these