Equipment:
Peristaltic pump, Sample loop and injection valve, Flow cell, pump tubing and connectors.
Apparatus:
Volumetric flasks 25ml, 250ml, Hotplate, Stopwatch.
Chemicals:
Ammonium molybdate, (NH4)6 Mo7O24.4H2O, FW = 1235.9
Potassium dihydrogen phosphate, KH2PO4, FW = 138
Ascorbic acid, FW = 176.12
Conc. nitric acid, HNO3
Sample:
Detergent (Breeze) 0.5g, or Fertilizer 0.25g
Solutions preparation:
Prepare all reagents using distilled de-ionised water.
1. 0.125M ammonium molybdate (FW = 1235.90) in 2M nitric acid. (weigh out 24.50g of the salt, add 122mls of conc. HNO3 and dilute to 1 liter with distilled water}
2. 0.05% ascorbic acid : dissolve 1g in 200mls distilled water (prepare fresh daily).
3. 1000 ppm phosphate std. Use AR potassium dihydrogen phosphate. Dry in oven at 80°C to remove moisture. Dissolve 1.45g in 1 liter distilled water.
Analytical notes:
1. Sonicate all reagents before measuring.
2. Digest Fertilizer sample with 5ml conc. HNO3.
3. Range of stds. 10, 20, 30, 40, and 50ppm phosphate.
4. Measure molybdenum blue complex at 800nm. or 820nm.
5. Sample preparation for breeze
Predigest 0.5g with 15mls conc HNO3 in a 250ml beaker overnight. Add 100 mls distilled water and boil on hotplate for 10 mins. , cool, and filter into a 250 vol. flask and make up to the mark with distilled water. Make a 1 in 10 dilution for measurements. eg 2.5mls in 25mls.
6. Flush system with 4M H2SO4, then with distilled water.
Operation of Instrument:
Follow User Guide: obtain help and advice from Demonstrator or Technician
delloyd infolab