Hach DR2400 - Page 656

Phosphorus, Reactive (Orthophosphate)
© Hach Company, 2003. All rights reserved. Printed in the U.S.A. 3/04 1ed
Page 4 of 4 PhosphorusReac_UniCell_Asc_Eng_Ody.fm
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Standard Solution Method
1. Use the 10-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
10 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: 7.5 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.
Required Reagents
Description Unit Cat. No.
Phosphate - PO
4
3–
, LR, UniCell™ HCT 121 ................................................................... 23/pkg.............. HCT 121
Required Apapratus
Adapter, 16-mm Cell .......................................................................................................... each....................59457-00
Optional Apparatus
Cylinder, mixing, 100-mL graduated............................................................................... each........................508-42
Digital Reactor Block 100................................................................................................... each....................DRB 100
Pipettor, Jencons, 100–1000 µL.......................................................................................... each....................27949-00
Tips, replacement for 27949-00 ......................................................................................... 400/pkg.............27950-00
Rack, Cooling, Test Tube.................................................................................................... each....................18641-00
Optional Standards
Hydrochloric Acid Solution, 1:1....................................................................................... 500 mL...................884-49
Phosphate Standard, 10-mL Voluette
®
Ampule, 500-mg/L as PO
4
............................ 16/pkg...............14242-10
Phosphate Standard, 10-mg/L as PO
4
............................................................................. 946 mL...............14204-16
Program 95% Confidence Limits of Distribution
806 7.2–7.8 mg/L PO
4
3–
Program Portion of Curve ∆Abs ∆Concentration
806 Entire range 0.010 0.2 mg/L PO
4
3–