Hach DR2400 Manual page 669

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Method Performance
Summary of Method
PhosphorusTot_TNT_Other_PAP_Eng_Ody.fm
6. 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.
7. Analyze each standard addition sample as described above (use a 5-mL
aliquot of the spiked sample as the sample). Accept each standard additions
reading by touching
100% recovery.
8. 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
1. Use a 1.0-mg/L phosphate standard solution in place of the sample. Perform
the procedure as describe above.
2. To adjust the calibration curve using the reading obtained with the
3–
1.0-mg/L PO
Phosphate Standard Solution, touch
4
program menu. Touch
3. 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
For more information, see Section 3.2.4 Adjusting the Standard Curve on page 40.
Precision
Standard: 3.00 mg/L PO
Program
536
See Section 3.4.3 Precision on page 44 for more information, or if the standard
concentration did not fall within the specified range.
Sensitivity
Portion of Curve
Entire range
See Section 3.4.5 Sensitivity on page 44 for more information.
Phosphates present in organic and condensed inorganic forms (meta-, pyro-, or
other polyphosphates) must be converted to reactive orthophosphate before
analysis. Pretreatment of the sample with acid and heat provides the conditions
for hydrolysis of the condensed inorganic forms. Organic phosphates are
converted to orthophosphates by heating with acid and persulfate.
. Each addition should reflect approximately
Read
Graph
and touch
Ideal Line
OK
.
Standard Adjust
to accept the displayed concentration (the value
3–
4
95% Confidence Limits of Distribution
2.90–3.10 mg/L PO
∆Abs
0.010
Phosphorus, Total
to view the best-fit line through
to view the relationship between
on the current
Options
3–
4
∆Concentration
0.06 mg/L PO
Phosphorus, Total
Page 5 of 6
.
OK
3–
4

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