LaMotte ALKALINITY TEST KIT - Manual (Page 2)

PRO CE DURE
1.
Use the pipet (2-2178) to trasfer 50.0 mL of the water sample to an
Erlenmeyer flask (0433).
2. Add one drop of Sodium Thiosulfate (6155).
3. Add five drops of *Phenolphthalein Indicator, 1% (2246). Mix. If
solution turns red, proceed to Step 4. If a red color does not develop
the Phenolphthalein (P) Alkalinity is zero.
4. Fill the automatic buret with 0.02N Sulfuric Acid (6068). While
swirling flask, titrate until red color disappears. Record buret reading
as Reading P. If Total Alkalinity is to be determined, do not refill
buret, and proceed to Step 5.
5. Add five drops of *BCG/MR Indicator (2311) or Methyl Orange
Indicator (2230) to the clear sample from Step 4.
6. Continue titrating with 0.02N Sulfuric Acid (6068) until color
change indicates a suitable endpoint. The BCG/MR Indicator will
change from blue-green to pink. The Methyl Orange Indicator will
change from yellow to red. Record buret reading as Reading T.
7. If only Total Alkalinity is being determined, follow Steps 1 & 2.
Add five drops of *BCG/MR Indicator (2311) or Methyl Orange
Indicator (2230). Fill buret with 0.02N Sulfuric Acid (6068) and
titrate to endpoint as described in Step 6. Record buret reading as
Reading T.
8. Calculations of Test Results:
Phenolphthalein (P) Alkalinity (ppm) = 20 x Reading P
Total (T) Alkalinity (ppm) = 20 x Reading T
For more details of this procedure and the relationship of hydroxide,
carbonate, and bicarbonate alkalinity, see Method 403 for Alkalinity in
the APHA Standard Methods, 15th Edition, 1980.
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