1 0.05 % Polyacrylamide. Weigh 0.25 g polyacrylamide to 450 ml of double RO water
and stir overnight with a magnetic stirrer. Make up to 500 ml (Do not try to add the
double RO water to the polyacrylamide.)
4.2 1N Sodium hydroxide for pH adjustment. Weigh 20 g of sodium hydroxide, dissolve
and dilute with double RO water to 500 ml.
4.3 0.5 M sodium bicarbonate, pH 8.5 with polyacrylamide (extracting solution). Weigh
168 g of sodium bicarbonate and place in a 4L Erlenmeyer flask. Dissolve in about
3,900 ml double RO water. Add 20 ml of 0.05% polyacrylamide. Adjust pH to 8.50
with 1N sodium hydroxide (approximately 60-80ml). Add enough double RO water
to make to 4 L if necessary.
4.4 AutoAnalyzer Reagents:
4.4.1 Wash solution - 0.5 M sodium bicarbonate, pH 8.5 with polyacrylamide
(extracting solution).
4.4.2 2.5 N sulfuric acid - Add slowly 70 ml concentrated sulfuric acid to about
500 ml double RO water in a 1 L volumetric flask. Cool down and dilute to
mark.
4.4.3 Acid molybdate - Dissolve 4.3 g ammonium molybdate tetrahydrate
(NH4)6Mo7O24.4H2O) in about 200 ml of double RO water in a 1-liter
volumetric flask. Add carefully 52 ml concentrated sulfuric acid. Make to
volume with double RO water and shake well to mix.
4.4.4 1 %(w/v) Ascorbic acid solution (with SDS). Prepare this solution fresh each
time before use. Dissolve 5g of ascorbic acid in 500 ml of double RO water.
Add 10 -15 drops of 5% w/v sodium dodecyl sulfate (SDS) as a wetting
agent to improve the autoanalyzer bubble pattern.
4.5 Stock solution A (2000 ppm P) - Dry reagent grade potassium dihydrogen
phosphate (KH2PO4) at 105OC for 2 hr. Cool in a dessicator. Accurately weigh
out 4.394 g KH2PO4, dissolve in double RO water and dilute to 500 ml. Shake
well to mix.