Hach DR/850, Procedures Manual, Page: 431 / 460

431
9.
Add 5.0 mL of
deionized water to the
control tube.
10.
Add 5.0 mL of the
sample (or dilution) to
each sample vial.
Note: To determine the
approximate threshold level
of toxicity for a sample,
dilute 1 mL of sample to 10
mL of deionized water and
run the test. Continue to
make serial 1:10 dilutions
until a level is reached
which gives a 0%
Inhibition in Step 18.
11.
Add 2 drops of
Accelerator Solution to
each vial. Cap and invert
to mix.
12.
Add 0.5 mL of
inoculum (previously
prepared) to each vial.
Cap and invert to mix.
13.
Place the control
vial in the cell holder.
Tightly cover the vial
with the instrument cap.
14.
Press:
READ
The cursor will move to
the right, then the result
in ABS will be
displayed. Record the
absorbance of the
“control” vial.
15.
Repeat Steps 13-14
for all samples and
dilutions. Be sure to
record each absorbance.
16.
Allow the solutions
in the tubes to react until
the absorbance of the
control tube decreases
0.60 ±0.10.
This should take about
45-75 minutes.
All Samples
Record Each
Absorbance
45-75 Minutes
TOXTRAK TOXICITY TEST,
continued