Phosphorus, Total
Phosphorus, Total
Page 4 of 6
PhosphorusTot_UniCell_Other_APD_Eng_Ody.fm
6. Prepare three sample spikes. Fill three mixing cylinders with 25 mL of
sample. Use a pipet to add 0.1 mL, 0.2 mL, and 0.3 mL of standard,
respectively, to each cylinder. Mix well.
7. 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
Read. Each addition should reflect approximately 100% recovery.
8. After completing the sequence, touch
Graph to view the best-fit line through
the standard additions data points, accounting for matrix interferences. Touch
View: Fit, then select Ideal Line and touch OK to view the relationship between
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 30-mg/L Phosphate Standard Solution listed under Optional Standards.
Perform the phosphate procedure as described.
2. To adjust the calibration curve using the reading obtained with the
30-mg/L PO
4
3–
Phosphate Standard Solution, touch Options on the current
program menu. Touch
Standard Adjust.
3. Touch
On. Touch Adjust to accept the displayed concentration (the value
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
OK.
Touch
Adjust.
For more information, see Section 3.2.4 Adjusting the Standard Curve on page 40.
Method Performance
Precision
Standard: 30.0 mg/L PO
4
3–
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
See Section 3.4.5 Sensitivity on page 44 for more information.
Summary of Method
Phosphate ions react with molybdate and antimony ions in an acidic solution to
form an antimonyl phosphomolybdate complex. Ascorbic acid reduces this
complex to phosphomolybdenum blue. Test results are measured at 880 nm.
Program 95% Confidence Limits of Distribution
804 29.5–30.5 mg/L PO
4
3–
Program Portion of Curve ∆Abs ∆Concentration
804 Entire range 0.010 0.5 mg/L PO
4
3–
To Next Page
Loading...
