DISSOLVED PHOSPHATE ANALYSIS
UPDATED OCTOBER 98  (MS)

METHOD:
From A Manual of Chemical and Biological Methods for Seawater Analysis, (Parsons, Maita, & Lalli, 1984)

REAGENTS:

Ammonium molybdate solution
15 g ammonium paramolybdate in 500 mL dist. H2O.
Store in plastic bottle away from direct sunlight.
Solution is stable.

Sulfuric acid solution
140 mL conc.(sp.gr.1.82) in 900 mL dist. H2O.
Store in glass bottle.

Ascorbic acid solution
27 g ascorbic acid in 500 mL dist. H2O.
Store solution in plastic bottles in freezer.
Stable for many months frozen, less than one week at room temp.

Potassium antimonyl-tartrate solution
0.34 g K-antimonyl-tartrate in 250 mL dist. H2O, warming if necessary.  Store in glass or plastic bottle.
Stable for many months.


Mixed Reagent (for 5 mL samples)
2 mL Ammonium molybdate
5 mL Sulfuric acid
2 mL Ascorbic acid
1 mL K-antimonyl-tartrate

PHOSPHATE STANDARDS:

 Primary STDs - both Analytical and Quality Control  12 mM - 0.816 g potassium dihydrogen phosphate, KH2PO4 (F.W. 136.09) in 500 ml nanopure H2O, with 1 mL chloroform. 1 mL = 12 (moles.

Secondary STDs - both Analytical and Quality Control - 1 mL primary STD / 100 mL H2O = 120 (M .
Primary and secondary STDs are stable and kept refrigerated.



Tertiary (Analytical) Standards:
	

3 STD ((M)
mL  2 STD / 100 mL H2O
0.0
0.00
0.6
0.50
1.8
1.50
3.0
2.50
4.2
3.50

Quality Control STD

2.0
1.67


ANALYSIS:
Measure 5 mL each of: 1X dist. H2O blanks, 1X each STD, and 1X each sample into culture tubes.
Add 0.5 mL mixed reagent.
Wait 5 minutes.
 Measure absorbence on a specrophotometer.


Operation of Spectronic 20D+ Spectrophotometer

Turn on & warm up for 15 minutes.
Set wavelength to 885 nm.
Set filter lever to the right.
Set 0% T
Change mode to Absorbence.
Insert nanopure water blank.
Set to 0 Absorbence.
Insert sample, read, and record in notebook.

 
Operation of  Diode Array Spectrophotometer

Measure absorbence in a 1 cm cuvette @ 820 nm on spectrophotometer (max wavelength on ours - not 885 nm).

Computer will not boot up with printer on.
General Scanning
Files-F6
Load parameter file - "Phosphat.
Sample Input-F8
Edit Sample Table
	Build STD & sample table here
Measure blank (H20 in cuvette)-F2. Measure sample-F1
At end, Hardcopy-F9, to print results

"Phosphat" parameters
F3 - Functions
	Set Fn1 at 820 nm.
F5 - Options
	Wavelength list mode
	Single spectrum
	F8 - Sample input
	Manual input 
            Use sample table
7/22/99

