LaMotte DCL-20 Colorimeter - Manual (Page 14)

CHLORIDE TEST
DIRECT READING TITRATOR METHOD
QUANTITY CONTENTS CODE
15 mL *Chloride Reagent #1 *4504-E
60 mL *Silver Nitrate, 0.141N *3062DR-H
1 Extracting Tube, plastic, w/cap 0989
1 Spoon, 1g 0697
1 Test Tube, 5-10-15 mL, glass, w/cap 0778
1 Direct Reading Titrator, 0-1000 Range 0384
*WARNING: Reagents marked with a * are considered hazardous substances. Material Safety Data Sheets (MSDS) are
supplied for these reagents. For your safety, read label and accompanying MSDS before using.
Chlorides are present in practically all soils. Application of fertilizer may increase chloride levels. Chlorides are removed
from soil by leaching. Excessive concentrations are toxic to plants. A high test reading, particularly where stunted growth
has been observed, may indicate poisoning due to high chloride levels in the soil.
RANGE: 0-1000 lbs/A
METHOD: In a neu tral or slightly al ka line so lu tion, po tas sium dichromate in di cates the end point of the sil ver
ni trate ti tra tion.
IN TER FER ENCES: Bro mine, Io dide, and Cy a nide reg is ter as equiv a lent chlo ride con cen tra tions.
Carefully read the LaMotte Direct Reading Titrator Manual before performing the titration procedure described below. The Titrator is
calibrated in terms of parts per million chloride and each minor division on the Titrator scale equals 20 ppm.
PROCEDURE
1. Fill a clean extracting tube (0989) to the mark with deionized water.
2. Add 3 one gram measures of soil using the 1 g spoon (0697). Cap tube and shake for five minutes.
3. Filter and collect all of the soil filtrate using the funnel (0459) and filter paper (0463). The filtrate does not have to be
clear since a slight turbidity does not interfere in the test.
4. Fill the test tube (0778) to the 10 mL line with the filtrate.
5. Add three drops of *Chloride Reagent #1 (4504) to the sample. Cap and shake to mix. A yellow color will result.
6. Fill the Direct Reading Titrator (0384) with *Silver Nitrate, 0.141 (3062DR) in the manner described in the
instruction manual.
7. Titrate the test sample with *Silver Nitrate, 0.141 (3062DR) until the yellow color changes permanently to
pink. Record the Titrator reading. If the plunger reaches the bottom mark (1000 ppm) on the Titrator scale before the
endpoint color change occurs, refill the Titrator and continue the titration procedure. Be sure to include the value of
the original amount added (1000 ppm) when recording the final result.
This test is valuable on saline soils or when contamination from sea water or sea spray is suspected. Normal soils of humid
regions rarely give readable tests, except when recently receiving liberal amounts of fertilizers containing chlorides.
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1985-01 • 10/01