Hach DR2400 Manual page 736

Sulfate
Accuracy Check
Sulfate
Page 4 of 6
Standard Additions Method (Sample Spike)
1. After reading test results, leave the sample cell (unspiked sample) in the
instrument.
2. Touch . Touch
Options
additions procedure will appear.
3. Touch to accept the default values for standard concentration, sample
OK
volume, and spike volumes. Touch
are accepted, the unspiked sample reading will appear in the top row. See
Standard Additions in the instrument manual for more information.
4. Snap the neck off a Sulfate 2-mL Ampule Standard, 1000-mg/L sulfate.
5. Prepare three sample spikes. Fill three mixing cylinders (Cat. No. 1896-40)
with 25 mL of sample. Use the TenSette Pipet to add 0.1 mL, 0.2 mL, and
0.3 mL of standard, respectively, to each sample and mix thoroughly.
6. Transfer 10 mL of each sample spike to a clean sample cell and analyze each
sample spike as described in the procedure above, starting with the 0.1 mL
sample spike. Accept each standard additions reading by touching
Each addition should reflect approximately 100% recovery.
Note: For AccuVac Ampuls, fill three Mixing Cylinders (Cat. No. 1896-41) with 50 mL of sample
and spike with 0.2 mL, 0.4 mL, and 0.6 mL of standard. Transfer 40 mL from each of the
three mixing cylinders to three 50-mL Beakers (Cat. No. 500-41). Analyze each standard
addition sample as described in the procedure above. Accept each standard additions
reading by touching Read. Each addition should reflect approximately 100% recovery.
7. After completing the sequence, touch
the standard additions data points, accounting for matrix interferences. Touch
, then select
View: Fit
the sample spikes and the "Ideal Line" of 100% recovery.
See Section 3.2.2 Standard Additions on page 32 for more information.
Standard Solutions
Prepare a 70-mg/L sulfate standard solution as follows:
1. Using Class A glassware, Pipet 7 mL of Sulfate Standard Solution,
1000-mg/L, into a 100-mL volumetric flask. Dilute to the mark with
deionized water. Prepare this solution daily. Perform the SulfaVer
procedure as described above.
2. To adjust the calibration curve using the reading obtained with the 70-mg/L
standard solution, touch
.
Standard Adjust
3. Touch . Touch
On OK
concentration is used, touch
Touch .
OK
See Section 3.2.4 Adjusting the Standard Curve on page 40 for more information.
. A summary of the standard
Standard Additions
to change these values. After values
Edit
Graph
and touch
Ideal Line OK
on the current program menu. Touch
Options
to accept the displayed concentration. If an alternate
and then enter the actual concentration.
Adjust
Read
to view the best-fit line through
to view the relationship between
Sulfate_AVPP_Other_SV4_Eng_Ody.fm
.