LaMotte SMART Spectro Spectrophotometer - Manual (Page 232)

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.
þNOTE: 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 determine the reagent blank only
when a new lot number of reagents are obtained.
SMART SPECTRO TEST PROCEDURES 05.04 Zinc 3/3