Table of Contents
Advertisement
Sample Collection, Preservation, and Storage
Accuracy Check
ChromiumHex_UniCell_Other_DCH_Eng_Ody.fm
Collect samples in a cleaned glass or plastic container. Store at 4 °C (39 °F) up to
24 hours. Samples must be analyzed within 24 hours.
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. Pipet 0.1, 0.2, and 0.3 mL of 50-mg/L Cr
three 25-mL samples and mix thoroughly.
5. Transfer 4 mL of each solution to three sample vials and analyze as described
in the procedure. Accept each standard additions reading by touching
Each addition should reflect approximately 100% recovery.
6. 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 Solution Method
Prepare a 0.70-mg/L Cr
1. Using a pipet, transfer 1.40 mL of Hexavalent Chromium Standard Solution,
50-mg/L, into a Class A 100-mL volumetric flask.
2. Dilute to the mark with deionized water.
3. To adjust the calibration curve using the reading obtained with the
0.70-mg/L standard solution, touch
Touch
Standard Adjust
4. Touch
. Touch
On
Adjust
depends on the selected chemical form). If an alternate concentration is used,
touch the number in the box to enter the actual concentration, then touch
Touch
.
Adjust
Perform the hexavalent chromium procedure as described above. See Section
3.2.4 Adjusting the Standard Curve on page 40 for more information.
Chromium, Hexavalent
. A summary of the standard
Standard Additions
to change these values. After values
Edit
6+
standard solution, respectively, to
Graph
and touch
Ideal Line
OK
6+
Standard solution daily, as follows:
Options
.
to accept the displayed concentration (the value
to view the best-fit line through
to view the relationship between
on the current program menu.
Chromium, Hexavalent
Page 3 of 4
.
Read
.
OK
Advertisement
Table of Contents
