LaMotte SMART Spectro Spectrophotometer - Manual (Page 114)

HEXAVALENT CHROMIUM PROCEDURE
Use universal sample holder.
1. Press and hold ON button until spectrophotometer turns on.
2. Scroll to and select 22 Chromium from menu.
3. Scroll to and select ALL TESTS (or another sequence containing
22 Chromium) from TESTING MENU.
4. Scroll to and select 22 Chromium from menu.
5. Rinse a clean tube (0290) with sample water. Fill to 10 mL line with sample
water.
6. Insert tube into chamber, close lid and select SCAN BLANK.
7. Remove tube from Spectro. Use 0.1 g spoon (0699) to add one level measure
of *Chromium Reagent Powder (V-6276). Cap and shake for one minute. Wait
3 minutes.
8. During the waiting period, fold a piece of fi lter paper in half, then in half again
to form a cone. Push corners together to open end, and insert into funnel
(0459).
9. At the end of 3 minute waiting period, fi lter sample into a clean tube (0290).
Cap and mix. Insert tube into chamber, close lid and select SCAN SAMPLE.
Record result.
10. Press OFF button to turn spectrophotometer off or press EXIT button to exit to
a previous menu or make another menu selection.
TOTAL CHROMIUM WITH ACID DIGESTION
PROCEDURE
1. Fill graduated cylinder (0418) to 50 mL line with sample water. Transfer to
Erlenmeyer fl ask (0431).
2. Use the 1 mL pipet (0354) to add 5 mL (fi ve measures) of *Sulfuric Acid, 5N
(7681). Swirl to mix.
3. NOTE: Highly buffered waters may require pH adjustment. Adjust the pH of
highly buffered samples to 7.0 ±0.5. Continue procedure.
4. Place fl ask on burner or hot plate. Bring solution to a gentle boil.
5. Fill pipet (0341) with Potassium Permanganate, 0.5% (7682). While gently
swirling fl ask, add Potassium Permanganate, 0.5% (7682), 2 drops at a time
to boiling solution, until solution turns a dark pink color which persists for 10
minutes. Continue boiling.
6. Add one drop of *Sodium Azide, 5% (7683) to boiling solution. Boil for
approximately 30 seconds. If pink color does not fade, add another drop of
*Sodium Azide, 5%. Continue adding *Sodium Azide, 5% one drop at a time
SMART Spectro Test Procedures 2.11 CHROMIUM-Hexavalent, Trivalent & Total
Test P
rocedures