1.    Using one of the 5 mL direct read titrators, pipette appropriate volume of sample into the 250 mL Erlenmeyer flask. For 50 and 100 mL sample volumes, use the graduation marks on the flask. For sample volumes less than 50 mL dilute to 100 mL mark with tap water. Swirl to mix

2.     Using a second direct read titrator, add 10 mL of Gardotest Solution 116 to the mixture in the flask. Swirl to mix.

3.     Add 2 heaping spoonful of Gardotest Powder 28. Swirl the flask to dissolve the crystals. The color of the solution should be reddish-orange or red.

4.     Fill a third titrator exactly to the zero mark with Gardotest Solution 29. Add this rapidly while swirling, to the contents of the flask until the color changes to a light yellow of greenish-yellow. Record the number of mL used.

5.     Using the 1 mL dropper, add 1 mL of Gardotest Indicator 17 to the mixture in the flask. Swirl to mix. The solution should turn dark blue or black.

6. Refill the third titrator exactly to the zero mark with Gardotest Solution 29. Add slowly to the flask while swirling, until the dark blue or black color disappears, and the solution turns colorless or pale green. Wait for 30 seconds, and if color comes back within 30 seconds, add more titrant drop by drop Repeat this till color does not come back within 30 seconds. Record the number of mL used. Add this number to the one recorded in step 4. This is Hexavalent Chromium titration. This completes Part I of the titration.

CALCULATION

Hexavalent Chrome Cr(VI) = mL of titrant from Part I (Total mL added from both step 4 & 6)
Concentration (vol % or oz/gal) = Cr(VI) multiplied by F

1.  Using the same 5 mL titrator from step 1 of Part I, pipette appropriate sample volume in to the 250 mL Erlenmeyer flask. Drop in 3 or 4 glass beads. Dilute to approximately 100 mL with water.

2.  Using a clean 5 mL titrator, pipette 10 mL of Gardotest Solution 218 into the flask and swirl to mix. If appreciable Trivalent Chromium is present, the color will change to emerald-green or yellow-green. The more trivalent chromium present, the more green the color will be.

3.  Using a clean 5 mL titrator, pipette 5 mL of Gardotest Solution 131 into the flask and swirl to mix. Vigorously boil the sample solution for at least 30 minutes. The color will change from yellow-green or emerald-green to lemon-yellow. Make sure to keep up the volume of solution with additions of water to 100 mL mark.

4.  After 30 minutes, while continuing the boiling, using a clean 5 mL titrator, slowly add Gardotest Solution 203 till the pH of the solution is 1 – 2. In some cases, the color will also change from lemon-yellow to light orange. Continue boiling the solution vigorously for 15 minutes longer while maintaining its volume with additions of water.

5.  After boiling for 15 minutes, remove the flask from the hot plate and allow the solution to cool down to room temperature.

6.  Using the 5 mL titrator, add 10 mL of Gardotest Solution 116 and swirl to mix.

7.  Add 2 heaping spoonful of Gardotest Powder 28. Swirl the flask to dissolve the crystals. The color of the solution should be reddish-orange or red.

8. Fill another titrator exactly to the zero mark with Gardotest Solution 29.  Add this rapidly while swirling, to the contents of the flask until the color changes to a light yellow of greenish-yellow. Record the number of mL used.
9. Using the 1 mL dropper, add 1 mL of Gardotest Indicator 17 to the mixture in the flask. Swirl to mix. The solution should turn dark blue or black.

10. Refill the third titrator exactly to the zero mark with Gardotest Solution 29. Add slowly to the flask while swirling, until the dark blue or black color disappears, and the solution turns colorless or pale green. Wait for 30 seconds, and if color comes back within 30 seconds, add more titrant drop by drop Repeat this till color does not come back within 30 seconds. Record the number of mL used. Add this number to the one recorded in step 8. This is Total Chromium titration. This completes Part II of the titration.