LaMotte SMART Spectro Spectrophotometer - Manual (Page 258)

PROCEDURE
Use universal sample holder.
A. PREPARATION OF DILUTE ZINC INDICATOR SOLUTION
1. Use a pipet (0352) to measure exactly 5.0 mL of *Zinc Indicator Solution (6314)
into 10 mL graduated cylinder (0416). The bottom of the curved surface (the
meniscus) of liquid should be at 5.0 mL mark. Pour this into the bottle labeled
“Dilute Zinc Indicator Solution”.
2. Use unrinsed graduated cylinder to add 10.0 mL and then 7.8 mL (total of 17.8
mL) of *Methyl Alcohol (6319) to bottle labeled “Dilute Zinc Indicator Solution”.
Cap and mix ingredients in this bottle. Do not leave this bottle uncapped.
B. DETERMINATION OF ZINC
1. Press and hold ON button until spectrophotometer turns on.
2. Scroll to and select PROGRAMMED TESTS.
3. Scroll to and select ALL TESTS (or another sequence containing
99 Zinc-LR) from TESTING MENU.
4. Scroll to and select 99 Zinc-LR from menu.
5. Rinse a clean tube (0290) with sample water. Fill to the 10 mL line with
sample.
6. Insert tube into chamber, close lid and select SCAN BLANK. (See Note)
7. Remove tube from Spectro. Use 0.1 g spoon (0699) to add one measure
of Sodium Ascorbate Powder (6316). Use 0.5 g spoon (0698) to add one
measure of *Zinc Buffer Powder (6315). Cap and shake vigorously for 1
minute. Some undissolved buffer may remain in the bottom of the tube.
8. Add 3 drops of *Sodium Cyanide, 10% (6565). Cap and mix.
9. Use the 1 mL pipet assembly to add 1 mL of “Dilute Zinc Indicator Solution”.
Cap and mix.
10. Use a second plain pipet (0352) to add 4 drops of *Formaldehyde Solution,
37% (5128). Cap and mix by inverting 15 times.
11. Insert tube into chamber, close lid and select SCAN SAMPLE. Record
result.
12. Press OFF button to turn spectrophotometer off or press EXIT button to exit to
a previous menu or make another menu selection.
NOTE: For best possible results, a reagent blank should be determined to account
for any contribution to the test result by the reagent system. To determine the
reagent blank, follow the above test procedure to scan a distilled or deionized
water blank. Then follow the above procedure to perform the test on a distilled or
deionized water sample. This test result is the reagent blank. Subtract the reagent
blank from all subsequent test results of unknown samples. It is necessary to
SMART Spectro Test Procedures 2.11 ZINC
Test P
rocedures