57-35
QUATERNARY AMMONIUM COMPOUNDS, continued
13. Place the
prepared sample in
the cell holder.
Note: Typical indoor
lighting permits the
DR/700 to operate with
the cell compartment
cover open. In bright
sunlight it may be
necessary to close the
cell compartment cover.
Transfer 10 mL of the
blank solution to a 10-
mL cell. If the
10-mL cell is used for
the blank, another
10-mL cell must be used
for the sample.
14. Press: READ
The display will
count down to 0.
Then the display will
show the results in
mg/L quaternary
ammonium
compounds as CTAB.
SAMPLING AND STORAGE
Collect samples in glass bottles that have been rinsed several times with
sample before final sample filling. Do not use plastic containers as
plastic adsorbs QACs.
ACCURACY CHECK
Standard Solution Method
To assure the accuracy of the test, use a 5 mg/L CTAB Standard Solution
prepared as follows:
a) Pipet 5 mL from the Q.A.C. Standard Solution, 100 mg/L as CTAB,
into a 100-mL volumetric flask.
b) Dilute the solution to 100 mL with demineralized water. Mix
thoroughly.
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