LaMotte DC1600 Colorimeter User Manual
Page 90
PROCEDURE
A. PREPARATION OF DILUTE ZINC INDICATOR SOLUTION
1.
Use a pipet (0352) to measure exactly 5.0 mL of *Zinc Indicator Solution into 10 mL graduated cylinder. 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.
Rinse a clean colorimeter tube (0967) with sample water. Fill to the 10 mL line with sample.
2.
Select setting 6 on “Select Wavelength” knob and press “30 Second Read” button.
3.
Insert tube into colorimeter chamber and adjust to 100%T with “Set Blank” knob. This is the 100%T blank.
4.
Remove tube from colorimeter. 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 Reagent (6315). Cap and shake vigorously for 1 minute.
5.
Add 3 drops of *Sodium Cyanide, 10% (6565). Cap and mix.
6.
Use the 1 mL pipet assembly to add 1 mL of “Dilute Zinc Indicator Solution”. Cap and mix.
7.
Use a second plain pipet (0352) to add 4 drops of *Formaldehyde Solution, 37% (5128). Cap and mix by inverting
15 times.
8.
Press the “30 Second Read” button and insert tube into colorimeter chamber. Record %T as soon as the reading
stabilizes.
9.
Consult calibration chart to determine zinc concentration in parts per million (ppm).
NOTE: It is suggested for best possible results to carry a reagent blank through the procedure to compensate for any
color which may develop within the reagents. Set the reagent blank to 86%T, then continue with unknown sample
tests.
DC1600 ZINC CALIBRATION CHART
%T
9
8
7
6
5
4
3
2
1
0
90
80
0.00
0.01
0.02
0.03
0.04
0.05
0.06
70
0.07
0.08
0.09
0.10
0.11
0.13
0.14
0.15
0.16
0.17
60
0.18
0.20
0.21
0.22
0.23
0.25
0.26
0.27
0.29
0.30
50
0.32
0.33
0.35
0.36
0.38
0.39
0.41
0.43
0.44
0.46
40
0.48
0.50
0.51
0.53
0.55
0.57
0.59
0.61
0.63
0.66
30
0.68
0.70
0.73
0.75
0.78
0.80
0.83
0.86
0.89
0.92
20
0.95
0.98
1.02
1.05
1.09
1.13
1.17
1.21
1.26
1.31
10
1.36
1.41
1.47
1.53
1.59
1.66
1.74
1.82
1.91
2.01
0
2.12
2.25
2.39
2.56
2.76
3.02
90