6
ERDC/CRREL TN-05-2
Figure 2. Blotting the test paper.
The area was allowed to dry thoroughly before applying the Expray solu-
tions. Drying time during this study was short (one minute) due to the use of the
high-vapor-pressure solvent ACN. The cans were shaken for 10 seconds, held
approximately 15 cm from the paper, and swept across the blotted area at an
approximate velocity of 8 cm/s while in a fume hood (respiratory precautions
were taken due to the solvents in this product). Expray 2 was then applied in the
same manner after Expray 1 was allowed to dry (approximately 30 seconds).
Expray 3 was not used in this experiment as it was not applicable to the nitro-
aromatic, nitramine, and nitrate esters in question.
Three phases of testing were conducted to study the four analytes. The first
phase was designed to establish an approximate operating range for the Expray
kit using 25, 50, 75, 100, 125, 150, 200, and 250 ppm of each of the four stan-
dards. Using the eight different types of paper, five sequences were performed
to test repeatability.
The second phase was designed to establish detection limits to 10 ppm. Ten
standards were made for each of the four analytes, ranging from 10 ppm to 100
ppm in 10-ppm increments. Having established the general repeatability of the
Previous Page
