LaMotte SMART 2 Electronic Soil Lab - Manual (Page 56)

PROCEDURE
I. DILUTION OF SOIL EXTRACT
Use the 30 mL graduated cylinder (0418) to measure 10 mL of the soil extract
and transfer it to a 50 mL beaker (0944). Add 10 mL of deionized water, mix
and neutralize according to the procedure on page 50.
II. TITRATION A, CALCIUM & MAGNESIUM
Carefully read the LaMotte Direct Reading Titrator Manual (1649) before
performing the titrations described below.
1. Fill the test tube (0778) to the 5 mL line with the soil extract from above.
Dilute to the 10 mL line with deionized water.
2. Add 5 drops of Calcium Magnesium Inhibitor Reagent (3922).
3. Wait 5 minutes.
4. Use a pipet (0364) to add 5 drops of *Calcium & Magnesium Buffer (5126).
5. Add 10 drops of *CM Indicator (6522WT).
6. Fill the Direct Reading Titrator (0384) with the Standard EDTA Reagent
(5254). Insert the tip of the Titrator into the center hole of the test tube
cap.
7. While gently swirling the tube, slowly press the plunger to titrate until the
color changes from red to blue.
8. Read the Titrator scale at the tip of the plunger and multiply by 5.16. This is
Titration Value A.
III. TITRATION B, CALCIUM
1. Fill the test tube (0778) to the 5 mL line with the diluted soil extract. Dilute
to 10 mL with deionized water.
2. Add 2 drops of *Inhibitor Solution (9258).
3. Add 2 drops of *TEA Reagent (3921).
4. Add 8 drops of *Sodium Hydroxide w/Metal Inhibitors (4259).
5. Add one Calcium-Hardness Indicator Tablet (T-5250) to the test sample.
Cap and shake to dissolve the tablet. A red color will develop.
6. Immediately titrate the sample. Fill the Direct Reading Titrator with
Standard EDTA Reagent (5254). Insert the tip of the Titrator into the hole
in the cap of the test tube.
7. While gently shaking the tube, slowly press the plunger to titrate until the
red color changes to a clear blue and does not revert to red upon standing
1-2 minutes.
8. Read the Titrator scale at the tip of the plunger and multiply by 5.16. This is
Titration Value B.
56 SMART2 SOIL MANUAL 1.07