LaMotte AM-41 Hydroponics Test Kit - Manual (Page 9)

3. Immediately insert test tube into the Sulfate Comparator (7779).
Match the sharpness of the lines behind the sample to the sharpness of
lines behind the standard. Record as ppm Sulfate.
NOTE:
Disregard any difference in color between the test sample and
standards.
NOTE:
Thoroughly rinse and clean test tubes after each test.
IRON
A special spot test method detects low concentrations of iron that are
present in the nutrient solutions. No dilutions are required, but it is
suggested that a blank be used as a means of comparison with the test
sample. The limit of detection is 0.25 ppm.
1.
Use pipet (0352) to add 4 drops of sample to a depression on the spot
plate (0159).
2. Use the 0.05 g spoon (0696) to add one measure of *Iron Reagent
Powder (5275). Mix with the stirring rod (0519).
3. Add 2 drops of *Ferric Iron Test Solution (5116PS). Use tablet
crusher (0175) to stir solution thoroughly. Solution will immediately
turn red or pink if iron is present.
CALCIUM AND MAGNESIUM
The Schwarzenbach EDTA titration method, used to determine calcium
and magnesium, involves two titrations. The first gives the combined
calcium and magnesium content and the second gives only the calcium
content. Magnesium is calculated from the difference between the two
titration values.
Read the Direct Reading Titrator Instruction Manual before proceeding.
TI TRA TION A, CAL CIUM AND MAG NE SIUM
1.
Fill the test tube (0645) to the line with the nutrient solution.
2. Add 5 drops of Calcium-Magnesium Inhibitor Reagent (3922). Swirl
to mix. Wait 5 minutes.
3. Add 5 drops of *Calcium & Magnesium Buffer (5126). Swirl to mix.
4. Add 10 drops of *CM Indicator Reagent (6522WT). Swirl to mix.
Solution will turn red.
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