Phosphorus, Acid Hydrolyzable
Phosphorus, Acid Hydrolyzable
Page 4 of 6
PhosphorusAcidHyd_TNT_Other_PHY_Eng_Ody.fm
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. 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.
7. 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 1.0-mg/L Phosphate Standard Solution in place of the sample. Perform
the procedure as described.
2. To adjust the calibration curve using the reading obtained with the 1.0-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: 3.00 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
Phosphates present in condensed inorganic forms (meta-, pyro-, or other
polyphosphates) must be converted to reactive orthophosphate before analysis.
Pretreating the sample with acid and heat hydrolyzes the condensed inorganic
forms to orthophosphate.
Orthophosphate reacts with molybdate in an acid medium to produce a mixed
phosphate/molybdate complex. Ascorbic acid then reduces the complex, giving
an intense molybdenum blue color. Test results are measured at 880 nm.
Program 95% Confidence Limits of Distribution
536 2.90–3.10 mg/L PO
4
3–
Portion of Curve ∆Abs ∆Concentration
Entire range 0.010 0.06 mg/L PO
4
3–
To Next Page
Loading...
