LaMotte BL-5 TEST KIT FOR CASI 773 - Manual (Page 4)

PROCEDURE
1.
Fill a test tube (0608) to the 25 mL line with sample water.
2. Add 2 drops of Sodium Thiosulfate, 0.1N (6155).
3. Use the 0.1 g spoon (0699) to add 0.3 g (3 measures) of Xylenol
Orange Powder (6165). Cap and mix until powder dissolves. Solution
color will range from purple to yellow.
4. If solution is yellow, add 1 drop of *Hydrochloric Acid, 0.5N (6025)
and proceed to Step 5. If solution is purple, add *Hydrochloric Acid,
0.5N (6025), one drop at a time, gently swirling after each drop, until
solution turns yellow. Add one more drop of *Hydrochloric Acid,
0.5N (6025).
5. Use the pipet (0344) to add *Thorium Nitrate (6158PS), one drop at
a time, until solution changes from yellow to bright pink. Swirl after
each drop and count the number of drops added. This is Value A.
6. Repeat Steps 1 through 5 on makeup water. Count the number of
drops added. This is Value B.
CASI 773 Concentration, ppm = 1.2 (Value A - Value B)
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