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Determination of phosphorus content in EDOT
2019-04-22
来源：亚科官网
EDOT, known as 3,4-ethylenedioxythiophene, is an excellent conductive, highly stable polymer with a wide range of applications in organic semiconductors, solid electrothermal containers, antistatic coating capacitors, and electrode materials. How to improve the purity of EDOT and reduce the content of impurity phosphorus is an urgent problem to be solved in the chemical industry.
Experimental principle
EDOT trace phosphorus is digested with nitric acid and perchloric acid, and is present in the form of phosphoric acid. In the sulfuric acid solution, ammonium molybdate is formed with ammonium molybdate, and reduced to phosphorus molybdenum blue by stannous chloride, and the color is measured at a wavelength of 690 nm. The reaction formula is:
24(NH4)2MoO4+H3PO4+21H2SO4=2[(NH4)3PO4·12MoO3]+21(NH4)2SO4+24H2O
(NH4)3PO4·12MoO3+SnCl2+5HCl=3NH4Cl+SnCl4+2H2O+2(Mo2O5·4MoO3)·HPO4
Experimental reagent material
Electronic balance: 200g, accuracy 0.1mg; visible spectrophotometer; Kjeldahl nitrogen bottle: 250mL; volumetric flask 500mL, 100mL, 50mL; electric thermostat drying oven: 50 °C~250 °C; adjustable electric furnace: 1kW; constant temperature water bath: 0~100°C; dryer: R240mm; nitric acid: analytically pure; perchloric acid: analytically pure; ammonium molybdate solution: 2.5%, weigh 25g ammonium molybdate in 1000ml beaker, add 400ml water to stir and dissolve, add 280mL thick Sulfuric acid, transferred to a 1000mL volumetric flask, diluted to the mark, shaken;
Stannous chloride glycerol solution: 2.5%, weigh 2.5g of SnCI·2H2O in 100mL of glycerin, dissolved in a water bath, dissolved, cooled, transferred to a brown bottle;
Phosphorus standard solution: The pure grade potassium dihydrogen phosphate is baked in a 105 °C±2 °C electric heating oven for 1 h, taken out and cooled, weighed 0.2195 g (accurate to 0.1 mg) into a 250 mL beaker, deionized water Dissolve, transfer to a 1000ml volumetric flask, add 3ml concentrated nitric acid, dilute to the mark with water, shake well, this solution contains phosphorus 50μg/mL.
Experimental method
1. Sample treatment: Weigh 2g sample (accurate to 0.1mg) in 250mL Kjeldahl nitrogen bottle, add 30mL concentrated nitric acid, heat on electric stove and boil until yellow smoke is exhausted, add 10ml perchloric acid, continue heating to white Smoke, until the solution is transparent, remove the nitrogen fixed bottle, add 30mL of deionized water after cooling, boil on the electric furnace, cool, and transfer to a 100mL volumetric flask for constant volume.
2. the working curve is drawn: accurately absorb the phosphorus standard solution (50μg/mL) 0.0 mL, 0.20mL, 0.40mL, 0.60mL, 0.80mL, 1.00mL, 1.20mL in a 50mL volumetric flask, add deionized water 20mL, 2.5% 2 mL of ammonium molybdate, mix well,
Add 2.5% stannous chloride glycerol solution to 0.25 mL, dilute to the mark with water, shake well, place for 20 min, 1 cm cuvette, 690 nm, with reference to the blank, and measure the absorbance A on a spectrophotometer.
(1).png)
3. Sample measurement: Pipette 20 mL of the diluted solution, transfer it into a 50 mL volumetric flask, add 20 mL of deionized water, 2 mL of 2.5% ammonium molybdate, mix well, add 0.25 mL of 2.5% stannous chloride glycerol solution, dilute with water to the mark. Shake well, place for 20 min, 1 cm cuvette, 690 nm, with reference to the blank, and measure the absorbance A on a spectrophotometer. The concentration of the sample was determined from the working curve and the phosphorus content was calculated.
(1).png)
Experimental result calculation
The phosphorus content in the sample is calculated according to formula (1):
(1).png)
Where: X———the phosphorus content in the sample, mg/L; C———from the curve find the phosphorus content, μg; m——the quality of the sample, g.
Allow the difference between two parallel determination results to be no more than 0.2mg/L, take
The arithmetic mean is the measurement result.
Related links: EDOT
Edited by Suzhou Yacoo Science Co., Ltd.
