Method for measuring trace quantity of prussiate in water by using dual-wavelength superposition spectrophotometry

A technique of spectrophotometry and cyanide, applied in the direction of color/spectral characteristic measurement, etc.

Inactive Publication Date: 2011-11-30
吴佑琼
1 Cites 13 Cited by

AI-Extracted Technical Summary

Problems solved by technology

The national standards for the determination of trace cyanide in surface water and drinking water mainly include the isonicotinic acid-pyrazolone photometric method, isonicotinic acid-barbituric acid photometric method and py...
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Method used

Use this method to 0.50 μ g and 2.00 μ g CN-standard solution and 2 parts of water sample distillates parallel measurement 5 times, its measured value is respectively 0.51 μ g ...
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Abstract

The invention discloses a method for measuring trace quantity of prussiate in water by using dual-wavelength superposition spectrophotometry. Under the condition that chloramine T exists in a weak acid medium, the prussiate and isonicotinic acid-thiobarbituric acid form red-blue dye which has a principle of dual absorption peaks; a novel method for measuring the trace quantity of prussiate in water through experiment, namely the isonicotinic acid-thiobarbituric acid dual-wavelength superposition spectrophotometry is established and provides a simple, convenient and sensitive analyzing method for measuring the trace quantity of prussiate in a water sample; and meanwhile, the application range of thiobarbituric acid is widened.

Application Domain

Color/spectral properties measurements

Technology Topic

SpectrophotometryChloramine +9

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  • Method for measuring trace quantity of prussiate in water by using dual-wavelength superposition spectrophotometry
  • Method for measuring trace quantity of prussiate in water by using dual-wavelength superposition spectrophotometry
  • Method for measuring trace quantity of prussiate in water by using dual-wavelength superposition spectrophotometry

Examples

  • Experimental program(1)
  • Effect test(1)

Example Embodiment

[0016] Examples:
[0017] 1. Main instruments and reagents:
[0018] UV-Vis Spectrophotometer: TU-1810SPC, Beijing Puxi General Instrument Co., Ltd.;
[0019] Cyanide standard solution: 0.10 mg/mL (the exact concentration is calibrated by the silver salt method), diluted to 1.0 μg/mL with 0.05 mol/L NaOH before use; 0.05 mol/L potassium dihydrogen phosphate/sodium hydroxide buffer solution : PH 5.8;
[0020] Isonicotinic acid-thiobarbituric acid solution: Weigh 2.0 g of thiobarbituric acid and 2.5 g of isonicotinic acid, add 28 to 30 mL of 1.0 mol/L NaOH solution, stir to dissolve and then use pure water to determine Volume to 100 mL (the pH of this solution is near neutral);
[0021] Chloramine T solution: 10.0 g/L, prepared just before use;
[0022] NaOH solution; 0.50, 0.05 mol/L;
[0023] Acetic acid solution (3+97);
[0024] 1.0 g/L phenolphthalein indicator;
[0025] The above reagents are analytically pure, and the experimental water is ultrapure water (18.25 ΜΩ·cm).
[0026] 2. Measurement steps:
[0027] (1) Take 0~5.0 mL cyanide standard solution into multiple 10 mL colorimetric tubes, add 0.05 mol/L NaOH solution to 5 mL, add phenolphthalein indicator and acetic acid solution to adjust until the red color just disappears, add buffer Mix 2.0 mL of the solution and 0.20 mL of the chloramine T solution, leave it for 4 minutes, add 2.0 mL of isonicotinic acid-thiobarbituric acid solution and add pure water to the mark 10 mL to mix evenly. Take the reagent blank as a reference and use 2 cm cuvette to measure the maximum absorbance A of each tube in 2~4 min at 525 nm λ1 , Continue to place for 35 min, measure the absorbance A at 642 nm of each tube in the same way λ2 , Calculate ΔA= A λ1 + A λ2 , In CN - Draw a standard curve of content versus ΔA;
[0028] (2) Take 250 mL of cyanide-containing water sample for distillation, use 5.0 mL of 0.50 mol/L NaOH solution as absorption liquid, collect the distillate to 50.0 mL, aliquot 5.0 mL each time and determine the absorbance according to step (1) ΔA, quantify cyanide by the standard curve method, and use the isonicotinic acid-barbituric acid photometric method for method comparison, and do the spike recovery test at the same time;
[0029] (3) Under the experimental conditions of step (2), CN - It forms a red-blue dye with isonicotinic acid-thiobarbituric acid. The dye has an absorption peak at 520~530 nm and 642 nm respectively by UV spectrophotometer, which can determine that the water sample contains oxides. .
[0030] 3. Analysis of test results:
[0031] Influence of coexisting substances
[0032] When measuring 0.20mg/L CN - , The relative error is within ±5%, and the following substances (in mg/L) are allowed to coexist: phenol (10); Cl - , SO 4 -2 , NO 3 - , F - , NH 4 + (20); NO 2 - , S -2 (5) It can be seen that the method has good selectivity.
[0033] 2.6 Standard regression curve
[0034] CN - The content in the range of 0~0.40μg/mL complies with Beer’s law. The regression equation of the standard curve and the apparent molar absorption coefficient obtained by the curve slope method are respectively: ΔA=3.547C (CN-, ug/mL) -0.0029, r=0.9996, ε=4.61×10 4 L/(mol·cm)
[0035] If ΔA=0.02, the minimum detectable concentration is 0.003μg/mL.
[0036] Color stability

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