Hach DR/700 Procedures Manual page 232

SULFATE,
continued
also needed when the water sample to be tested has an expected sulfate
concentration which is not between that of the standards last used to
calibrate the DR/700 module. Perform the calibration as follows.
Make 2 sulfate standards using the technique described in Step 4 of the
test procedure, Make them so one has a slightly lower and the other a
slightly higher concentration than that anticipated to be in the water
sample. Process each on the same way as the "displayed standard"
described in the test procedure.
Next perform paragraph 3.2.4.1, Calibration Using Two Prepared
Standards, in the DR/700 instrument manual. Either standard can be
used as Standard 1 (S1) or Standard 2 (S2).
INTERFERENCES
Silica and Calcium may interfere at levels above 500 and 20,000 mg/L
as CaCO respectively.
,
3
Chloride and magnesium do not interfere at levels up to at least
40,000 mg/L as Cl and 10,000 mg/L as CaCO
SUMMARY OF METHOD
Sulfate ions on the sample react with barium in the SulfaVer 4 Sulfate
Reagent and form insoluble barium sulfate turbidity. The amount of
turbidity formed is proportional to the sulfate concentration.
REQUIRED REAGENTS (Using Powder Pillows)
Description
SulfaVer 4 Reagent
Powder Pillows, 10 mL . . . 2 pillows . . . 100/pkg . . . . . . . 21067-69
Sulfate Standard Solution,
1000 mg/L . . . . . . . . . . . . . varies . . . . . . 500 mL . . . . . . . 21757-49
Water, demineralized . . . . . . . . . 1 L. . . . . . . . . 4 L . . . . . . . . . . . . . 272-56
REQUIRED REAGENTS (Using AccuVac Ampuls)
SulfaVer 4 AccuVac Ampuls . . 1 ampul . . . . 25/pkg . . . . . . . . 25090-25
Sulfate Standard Solution,
1000 mg/L . . . . . . . . . . . . . varies . . . . . . 500 mL . . . . . . . 21757-49
Water, demineralized . . . . . . . . 1 L . . . . . . . . 4 L . . . . . . . . . . . . 272-56
, respectively.
3
Quantity
Per Test Unit
45-60
Cat. No