SUMMARY AND CONCLUSIONS

100

DTECH Standard

80

Figure 13. Standard curve produced at

WES vs. the DTECH published curve.

Figure 14. RP-HPLC values vs.

20

0

DTECH values. Frequency of occur-

30

40

20

0

10

50

rence within each range.

TNT Equivalents, RP-HPLC (g/L)

The RDX kit performed so poorly that the man-

the extreme high values for wells 731 and 743

(Table 3). The RPD criterion had to be redefined; it

ufacturer was contacted for advice.* Other than a

was acceptable if the kit value and RP-HPLC val-

color development more rapid than anticipated,

ue fell within the same range. These kits failed

the kits passed the manufacturer's quality control

that test over half the time. The TNT kit produced

standards. Attempts to create a standard curve, as

the highest number of false positives--10 out of

was done for TNT, were unsuccessful.

33 wells. The question of false negatives can be

answered in two ways. The detection limit

SUMMARY AND CONCLUSIONS

claimed by the kit is 5 g/L, ten times higher than

the next most sensitive kit (EnviroGard). At this

The results of this investigation of 44 ground-

level no false negatives occurred. However, the

water wells were disappointing. None of the test

lack of false negatives is offset by the fact that the

kits performed as well as advertised. The quanti-

detection limit of 5 g/L is higher than the 2 g/L

tative assays were neither accurate nor precise

health advisory value proposed by the EPA for

enough to replace Method 8330 RP-HPLC deter-

drinking water (EPA 1989). The kit did fail to de-

minations, although they can be used adequately

tect TNT or its cross-reactive transformation

as screening tools. Of the two DTECH assays, the

products in nine samples that had measurable

RDX test failed badly by producing eight false

quantities by RP-HPLC. These kits might be con-

sidered when the detection limit is adequate and

* Personal communication, G.Teaney, Strategic Diagnostics,

the cost of false positives is low.

Newark, Del., 1994.

13