LaMotte Organic Matter In Soil Test Kit ST-OR - Manual

Or ganic Matter In Soil Test Kit
MODEL ST-OR • CODE 5020
QUANTITY CONTENTS CODE
230 mL *Potassium Dichromate, 1.0N *5159-K
2 x 230 mL *Sulfuric Acid, Concentrated *5172-K
475 mL *Ferrous Ammonium Sulfate, 0.4N *5117-L
50 mL *Diphenylamine Indicator *5114-H
90 g *Sodium Fluoride Powder *6550-S
1 Spoon, 0.5 g, plastic 0698
1 Spoon, teaspoon, plastic 0461
2 Flasks, Erlenmeyer, 250 mL, w/cap 0433
1 Graduated Cylinder, glass, 10 mL 0416
1 Graduated Cylinder, glass, 100 mL 0419
1 Buret, 25 mL 0428
1 Organic Matter Endpoint Color Standard 5334
1 Pipet, dropping, plastic 0352
*WARNING: Reagents marked with an * are considered to be potential health
hazards. To view or print a Material Safety Data Sheet (MSDS) for these reagents go
to www.lamotte.com. To obtain a printed copy, contact LaMotte by e-mail, phone or
fax.
To order a complete set of refill reagents, order as R-5020. To order individual
reagents or test kit components, use the specified code number.
Read the Automatic Buret Instruction Manual before proceeding.
NOTES
1. The soil should be air dried, crushed and filtered through a 20 mesh
screen before testing.
2. The soil sample should be 0.5 g. If possible, the sample should be
weighed to avoid error with heavy clay soils or light humus soils.
3. To avoid etching of the glassware by the *Sodium Fluoride Powder
(6550), wash and rinse all of the equipment immediately after testing.
PRO CE DURE
1. Use the spoon (0698) to measure 0.5g of the soil to be tested. Add to
one of the 250 mL Erlenmeyer flasks (0433).
2. Use the 10 mL graduated cylinder (0416) to add 10 mL of *Potassium
Dichromate, 1.0N (5159).
3. Use the 100 mL graduated cylinder (0419) to add 20 mL of *Sulfuric
Acid, Concentrated (5172).
NOTE: Add the acid very slowly, holding the mouth of the flask away
to avoid any spattering when the acid runs into the solution. As a safety
measure, protective glasses should be worn during this test. If acid is
spilled onto skin or clothing, flush immediately with water and apply
baking soda to neutralize any residual acid.
4. Stopper. Swirl the flask gently for one minute. The solution will be very
warm. After mixing, cool the flask and contents by holding under cold
water.
5. Repeat Steps 2, 3, and 4 using the second flask without a soil sample.
This will be a blank which must be run with every soil sample or group
of samples.
6. Use the 100 mL graduated cylinder (0419) to carefully add 100 mL of tap
water to each flask. Precautions against spattering should again be observed.
7. Use the plastic teaspoon (0461) to add one generous measure of
*Sodium Fluoride Powder (6550) to each flask. Stopper and shake until
dissolved.
8. Use the pipet (0352) to add 10 drops of *Diphenylamine Indicator
(5114) to each flask.
9. Fill the 25 mL buret to the 0 mark with the *Ferrous Ammonium
Sulfate, 0.4N (5117). While gently swirling the flask, titrate with
*Ferrous Ammonium Sulfate, 0.4N until color changes from dark
brown through blue to a deep green. Match color with Organic Matter
Endpoint Color Standard (5334). Titrate until colors match. Record
value from buret. Repeat with second flask.
NOTE: The change from blue to the final green is very rapid, so the
titrating solution should be added one drop at a time at this point.
10. The result is calculated from the formula:
% Organic Matter =
16 (Blank Value - Sample Value)
Blank Value
Help ing Peo ple Solve An a lyt i cal Chal lenges SM
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