Phosphate ~ high range – LaMotte DC1600 Colorimeter User Manual
Page 71
PHOSPHATE ~ HIGH RANGE
VANADOMOLYBDOPHOSPHORIC ACID METHOD
CODE 3655
QUANTITY
CONTENTS
CODE
60 mL
*VM Phosphate Reagent
*4410-H
1
Pipet, 1.0 mL, plastic
0354
*WARNING: Reagents marked with a * are considered hazardous substances. Material Safety Data Sheets (MSDS) are supplied for
these reagents. For your safety, read label and accompanying MSDS before using.
Phosphate treatment in boiler and cooling water and other industrial water systems are run at levels up to 100 ppm
orthophosphate. These high levels permit the use of a simpler, high range test.
APPLICATION:
Boiler, cooling, and industrial water.
RANGE:
0 – 80.0 ppm Orthophosphate
METHOD:
Orthophosphate reacts in acid conditions with ammonium vanadomolybdate to form
vanadomolybdophosphoric acid. This yellow color is proportional to the concentration of
orthophosphate and is read colorimetrically.
SAMPLE HANDLING
& PRESERVATION:
If the analysis cannot be performed the same day of collection, the sample should be preserved
by the addition of 2 mL of concentrated sulfuric acid or 40 mg mercuric chloride per liter and
refrigerated at 4°C.
INTERFERENCES:
Silica interferes only if the sample is heated. Arsenate, fluoride, thorium, bismuth, sulfide,
thiosulfate, and thiocyanate cause negative interference.
PROCEDURE
1.
Rinse a clean colorimeter tube (0967) with sample water. Fill to the 10 mL line with sample.
2.
Select setting 2 on “Select Wavelength” knob and press the “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 the 1.0 mL pipet (0354) to add 2.0 mL of *VM Phosphate Reagent (4410). Cap
and mix. Wait 5 minutes for full color development.
5.
At end of 5 minute waiting period, press the “30 Second Read” button and insert tube into colorimeter chamber.
Record %T as soon as reading stabilizes.
6.
Consult calibration chart to determine phosphate concentration in parts per million (ppm).
DC1600 PHOSPHATE ~ HIGH RANGE CALIBRATION CHART
%T
9
8
7
6
5
4
3
2
1
0
90
0.40
0.77
1.15
1.52
1.91
2.29
2.69
3.08
3.49
3.90
80
4.31
4.73
5.15
5.59
6.02
6.47
6.92
7.37
7.84
8.31
70
8.78
9.27
9.76
10.26
10.77
11.28
11.81
12.34
12.88
13.43
60
13.99
14.56
15.14
15.73
16.34
16.95
17.57
18.21
18.86
19.52
50
20.19
20.88
21.58
22.30
23.03
23.78
24.55
25.33
26.13
26.95
40
27.79
28.65
29.53
30.43
31.36
32.31
33.29
34.29
35.33
36.39
30
37.48
38.61
39.78
40.98
42.22
43.50
44.83
46.21
47.63
49.12
20
50.66
52.26
53.93
55.68
57.51
59.42
61.43
63.54
65.77
68.12
10
70.61
73.26
76.08
79.11
82.36
0
71