Hach DR/850, Procedures Manual, Page: 429 / 460

429
Method 10017
TOXTRAK
™
TOXICITY TEST
*
For water and wastewater
Colorimetric Method
**
* U.S. Patent number 5,413,916.
** Liu, D.,
Bull. Environ. Contam. Toxicol . 26, 145-149 (1981).
Inoculum Development
Using Indigenous Biomass
1.
Using one of the
dropper pipets provided,
add 1.0 mL of source
culture to a Tryptic Soy
Broth Tube.
2.
Incubate at 37 °C
until the vial contents
are visibly turbid
(turbidity indicates
bacterial growth).
Inoculum Development Using Aqua QC-Stiks
1.
Inoculate a Lauryl
Tryptose broth tube
with an E. coli Aqua
QC-Stik™ according to
the instructions that
come with the stick.
2.
Incubate the Lauryl
Tryptose Broth Tube at
35°C (95°F) until the
medium is visibly turbid
(approxamately 12
hours). Turbidity
develops much faster in
an incubator than at
room temperature.
3.
Inoculate a new
Lauryl Tryptose Broth
Tube by first inverting
the tube and switching
the caps of the two
tubes.
In this way, several
medium vials can be
inoculated from one
Aqua–QC Stick™.
4.
Invert the new tube.
After incubation, this
new vial may be used in
subsequent tests.
If toxicity tests will be
run on consecutive days,
inoculum may be kept
several days at room
temperature.
Cultures 10 to 72 hours
old give best results.