Hach DR/700 Procedures Manual page 728

PHOSPHORUS, REACTIVE,
STATISTICAL EVALUATION
A single operator repetitively tested samples of two laboratory prepared
solutions, using one DR/700, matched sample cells and two
representative lots of testing reagents. Testing 1.60 mg/L PO
concentration samples, the standard deviation was ±0.007 mg/L PO
Testing zero concentration samples, the limit of detection was
3-
0.019 mg/L PO
4
the standard deviation when testing zero concentration samples
(Adapted from Analytical Chemistry, 1980, 52, 2242-2249.
Using two representative lots of AccuVacs, the standard deviation was
±0.008 mg/L PO
4
SUMMARY OF METHOD
Orthophosphate reacts with molybdate in an acid medium to produce a
phosphomolybdate complex. Ascorbic acid then reduces the complex,
giving an intense molybdenum blue color.
REQUIRED REAGENTS (Using Powder Pillows)
Description
PhosVer 3 Phosphate Reagent
Powder Pillows . . . . . . . . . 1 Pillow . . . 100/pkg . . . . . . 21060-69
REQUIRED REAGENTS (Using AccuVac Ampuls)
PhosVer 3 Phosphate Reagent
AccuVac Ampuls . . . . . . . . 1 ampul . . . 25/pkg . . . . . . . . 25080-25
REQUIRED APPARATUS (Using Powder Pillows)
Clippers, for opening
powder pillows . . . . . . . . . 1 . . . . . . . . . each . . . . . . . . . . . 968-00
DR/700 Filter Module
Number 81.01. . . . . . . . . . . 1 . . . . . . . . . each . . . . . . . . . . 46281-00
REQUIRED APPARATUS (Using AccuVac Ampuls)
Beaker, 50 mL . . . . . . . . . . . . 1 . . . . . . . . . each . . . . . . . . . . . . 500-41
Cap, ampul, blue . . . . . . . . . . . 1 . . . . . . . . . 25/pkg . . . . . . . . . 1731-25
DR/700 Filter Module
Number 81.01. . . . . . . . . . . 1 . . . . . . . . . each . . . . . . . . . . 46281-00
. The limit of detection was calculated as three times
3-
and the limit of detection was 0.021 mg/L PO
Quantity
Per Test
continued
Unit
81-54
3-
4
3-
.
4
3-
.
4
Cat. No.