Formaldehyde oxime is a kind of carbonyl-containing aldehydes, ketones and hydroxylamine compounds generated by the action, this compound in the alkaline solution can be formed with manganese to form a brown-red compound, the determination of the absorbance of this brown-red compound, you can get the content of manganese by the formula.
This property can be used to detect the total manganese content in drinking water or other sources of water. The minimum detection mass is 1.0 ug, and if a 50mL water sample is taken for determination, the minimum detection mass concentration is 0.02mg/L.
1. Erlenmeyer flask 100mL
2. Plug colorimetric tube 50mL
3. Spectrophotometer
1. Nitric acid
2. Potassium persulfate
3. Sodium sulfite
4. Ammonium ferrous sulfate solution
Weigh 700mg of ferrous ammonium sulfate, add sulfuric acid solution (1 + 9) 10mL, dilute with laboratory first-class pure water to 1000mL.
5. Sodium hydroxide solution (160g/L)
Weigh 160 g of sodium hydroxide, dissolve in laboratory first-class pure water, and dilute to 1000 mL.
6. Disodium EDTA solution (372g/L)
Weigh 37.2g of disodium edta, add sodium hydroxide solution of about 50mL, stir until completely dissolved, dilute to 100mL with laboratory first-class pure water.
7. Formaldehyde oxime solution
Weigh 10g of hydroxylamine hydrochloride dissolved in about 50mL of laboratory first-class pure water, add 5mL of formaldehyde solution, dilute to 100mL with laboratory-level pure water, store the reagent in a cool place, at least 1 month.
8. Ammonia aqueous solution (0.88g/mL)
Take 70 mL of ammonia and dilute it to 200 mL with laboratory grade 1 pure water.
9. Hydroxylamine hydrochloride solution (417g/L)
Weigh 41.7 g of hydroxylamine hydrochloride solution in laboratory grade 1 pure water and dilute to 100 ml.
10. Ammonia hydroxylamine hydrochloride solution
The above aqueous ammonia solution and hydroxylamine hydrochloride solution are mixed in volumes.
11. Manganese standard stock solution (1mg/mL)
Weigh 1.2912g of manganese oxide or weigh 1.000g of manganese metal, add nitric acid (1+1) to dissolve, and use laboratory first-class pure water to fix the volume to 1000mL.
12. Manganese standard use solution (10ug/L)
Aspirate 5.00 mL of manganese standard stock solution with laboratory grade 1 pure water to a fixed capacity of 500 mL.
If the water sample to be tested contains suspended manganese and organic manganese, we can detect it after pretreatment, take a certain amount of water sample in an Erlenmeyer flask, add 0.5 mL nitric acid and 0.25 g of potassium persulfate per 50 mL of water sample, put in several glass beads, boil on the electric stove for 30 min, remove slightly cold, filter with rapid qualitative filter paper, and wash the filter paper several times with dilute nitric acid solution. About 0.5 g of sodium sulfite was added to the filtrate, and the volume was fixed with pure water to a certain volume as the test solution.
Take a 50 mL clean water sample or test solution in a 50 mL colorimetric tube.
In addition, 8 50mL cuvettes were added to 0mL, 0.10mL, 0.25mL, 0.50mL, 1.00mL, 2.00mL, 3.00mL and 4.00mL manganese standard solutions, and added laboratory-level pure water to the scale line.
Add 1.0mL of ferrous ammonium sulfate solution and 0.5mL disodium edta solution to the water sample and standard series tubes, mix well, add 0.5mL of formaldehyde oxime solution, and immediately add 1.5mL of sodium hydroxide solution, mix well and then open the tube plug and stand for 10min.
Add 3 mL of ammonia hydroxylamine hydrochloride solution, place at least 1 h, if the room temperature is lower than 15 ° C can be put into a warm water bath, and then at a wavelength of 450 nm, with a 5 cm cuvette to the laboratory grade pure water as a reference, measure its absorbance.
The standard curve is drawn, and the mass of manganese in the water sample tube is found, and the total manganese content in the water sample to be measured is calculated by formula.