Hach DR/850 Procedures Manual page 408

SULFATE,
continued
9.
Press:
ZERO
The cursor will move to
the right, then the
display will show:
0 mg/L SO4
User- Entered Calibration
10.
Within five minutes
after the timer beeps,
place the AccuVac
ampul into the cell
holder. Tightly cover the
sample cell with the
instrument cap.
There are various programs to determine sulfate, each with a
different level of accuracy. Best results are obtained by
performing a user-entered calibration with each new lot of
reagent. Programs 91 and 92 can be run when a high degree of
accuracy is not needed. Use of the Standard Adjust feature will
improve performance when using programs 91 and 92. It should
NOT be used with a user calibration, as it will hinder
performance.
Using Class A glassware, prepare standards of 10, 20, 30, 40, 50,
60, and 70 mg/L sulfate by pipetting 1, 2, 3, 4, 5, 6, and 7 mL of a
1000-mg/L sulfate standard into 100-mL volumetric flasks.
Dilute to the mark with deionized water and mix well.
Zero the instrument with water. The user-entered settings for
sulfate are:
Program number: #101 to 105
Wavelength: 520 nm
Resolution: 0 mg/L
See Creating User-Entered Program in the instrument manual for
specific instructions on entering a user-entered program.
11.
Press:
READ
The cursor will move to
the right, then the result
in mg/L sulfate will
be displayed.
Note: If Program 92 is
used, use of the Standard
Adjust is highly
recommended. See
Accuracy Check.
408