Hach DR2400 Manual page 304

Hardness, Total
Accuracy Check
Standard Solution Method
Hardness, Total
Page 4 of 6
Standard Additions Method (Sample Spike)
1. Touch . Touch
Options
additions procedure will appear.
2. Touch Change the sample volume to read 25 mL. Change the Standard
Edit.
Addition increments to 0.1 mL, 0.2 mL, and 0.3 mL. Touch
values. After the values are accepted, the unspiked sample reading will
appear in the top row. See Standard Additions in the instrument manual for
more information.
3. Obtain a Calcium Chloride Standard Solution, 20-mg/L (20,000-µg/L) as
CaCO .
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4. Prepare three sample spikes. Use a TenSette
0.3 mL, of a 20-mg/L as CaCO
samples, respectively.
5. 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. Each 0.1 mL
Read
addition of standard should cause an increase of 80 µg/L hardness as CaCO
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 for more information.
Using the 0.50-mg/L (500-µg/L as CaCO
perform the procedure using the standard in place of the sample.
1. To adjust the calibration curve using the reading obtained with the 500-µg/L
as CaCO Standard Solution, touch
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Touch
Standard Adjust
2. Touch . Touch
On Adjust
alternative concentration is used, touch the number in the box to enter the
actual concentration, then touch
See Section 3.2.3 Adjusting the Standard Curve for more information.
. A summary of the standard
Standard Additions
®
Calcium Chloride Standard to three 25-mL
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Graph
and touch
Ideal Line OK
) Calcium Chloride Standard Solution,
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Options
.
to accept the displayed concentration. If an
. Touch
OK Adjust
to accept these
OK
Pipet to add 0.1 mL, 0.2 mL, and
to view the best-fit line through
to view the relationship between
on the current program menu.
.
Hardness_MP_ULow_CPZ_Eng_2400.fm
.
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