LaMotte AM-21 Water Pollution Detection Outfit - Manual (Page 17)

Free Carbon Dioxide Test
Surface waters normally contain less than 10 ppm free carbon dioxide while
some ground waters may easily exceed that concentration. Corrosion is the
principal difficulty caused by high concentrations of carbon dioxide due to
lowering of pH when carbon dioxide dissolves in water to form carbonic
acid.
Free carbon dioxide is determined by a titration procedure using a base
solution with phenolphthalein as the endpoint indicator.
Field Test Method
Quantity Contents Code
15 mL *Phenolphthalein Indicator, 1% *2246-E
30 mL *Carbon Dioxide Reagent B *4253-G
1 Test Tube, 5-10-12.9-15-20-25 mL,
glass, w/cap 0608
1 Direct Reading Titrator, 0-50 Range 0380
WARNING: Reagents marked with a * are considered to be potential health hazards.
To view or print a Material Safety Data Sheet (MSDS) for these reagents see MSDS CD
or www.lamotte.com. To obtain a printed copy, contact LaMotte by email, phone or fax.
Read the LaMotte Direct Reading Titrator Manual before proceeding.
Procedure
1. Fill test tube (0608) to the 20 mL line with sample water. For best results
the test should be made on a freshly obtained sample, preferably a
sample obtained with a minimum of contact with the air (avoid
splashing, etc.)
2. Add 2 drops *Phenolphthalein Indicator, 1% (2246). If the test sample
turns red, no free carbon dioxide is present.
3. If the solution is colorless, titrate with *Carbon Dioxide Reagent B
(4253) until a faint but permanent pink color is produced and persists for
at least 30 seconds. Swirl the sample gently during the titration. Read the
result directly from the scale where the large ring on the Titrator meets
the Titrator barrel. Record the result in ppm Carbon Dioxide.
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