Method for detecting total phosphorus in water by ammonium molybdate spectrophotometry

A technology of spectrophotometry and ammonium molybdate, which is applied in the measurement of color/spectral characteristics, can solve the problems affecting the accuracy of the results and the measurement error of phosphorus element content, and achieve the effect of improving the detection accuracy

Inactive Publication Date: 2018-11-30
郑州市通标环境检测有限公司
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Problems solved by technology

[0003] However, during the above-mentioned treatment process, the silicon element in the water sample will form silicon dioxide, and the silicon dioxide and antimony salt will also form a blue complex, resulting in an error in the determination of the phosphorus content in the spectrophotometric detection. , affecting the accuracy of the results

Method used

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Examples

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Embodiment 1

[0045] In this embodiment, step [1], step [2] and step [3] are operated in accordance with the provisions of the national standard GB 11893-89 "Determination of Total Phosphorus-Ammonium Molybdate Spectrophotometry".

[0046] Between step [1] and step [2], an additional treatment process not specified in GB 11893-89 was added, as follows: after digestion with nitric acid-perchloric acid, dilute the digestion solution to 25ml, and dilute the 25ml All digestion solutions were used in subsequent processing. Put the digestion into the Erlenmeyer flask, adjust the pH of the solution to 3-5 with perchloric acid and sodium hydroxide, and the volume of the solution should be in the range of 27-32ml at this time. Then add 0.01g MgO into the solution, and stir the reaction (stirring can also be replaced by ultrasonic vibration), and the reaction time is 30min. Then the pH of the reacted solution is adjusted to 1-3 with perchloric acid and sodium hydroxide, at this time, the volume of t...

Embodiment 2

[0050] The treatment process of this example is basically the same as that of Example 1, except that potassium persulfate is used for digestion of the water sample, the reaction time after adding MgO to the digestion solution is 10 minutes, and the standing time after constant volume is completed is 60 minutes.

[0051] Using the method of this example, the prepared standard water sample with a phosphorus content of 0.510 mg / L was measured, and the measurement result obtained was that the phosphorus content was 0.508 mg / L. The measurement was carried out completely according to the method stipulated in GB 11893-89, and the result obtained was that the phosphorus content was 0.507mg / L.

[0052] Using the method of this example, the prepared standard water sample with a phosphorus content of 0.510 mg / L and a silicon content of 0.120 mg / L was measured, and the measurement result obtained was that the phosphorus content was 0.514 mg / L, which basically excluded silicon Impact. The...

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Abstract

The invention belongs to the technical field of spectrophotometry, and particularly relates to a method for detecting total phosphorus in water by ammonium molybdate spectrophotometry. A problem thatsilica formed by a silicon element in a water sample affects the test accuracy during the testing of the phosphorus content by ammonium molybdate spectrophotometry exists in the prior art. The methodin the invention comprises the following steps: [1] digesting the water sample to obtain a digestion solution; [2] adding ascorbic acid, an antimony salt and ammonium molybdate to the digestion solution to obtain a blue complex solution; and [3] testing the blue complex solution by spectrophotometry to obtain the phosphorus content of the water sample, wherein the digestion solution is also treated, between step [1] and step [2], as follows: [1-1] quantitatively transferring the digestion solution, adjusting the pH value to 3-5, adding MgO to the digestion solution, and carrying out a stirringreaction; [1-2] adjusting the pH value of the digestion solution to 1-3, and making the volume of the digestion solution reach a constant volume; and [1-3] standing the digested solution having the constant volume, and filtering the obtained solution by an ultrafiltration membrane to remove obtained precipitate. The method is suitable for water quality testing.

Description

technical field [0001] The invention belongs to the technical field of spectrophotometric analysis, in particular to a method for determining total phosphorus in water by ammonium molybdate spectrophotometric method. Background technique [0002] Ammonium molybdate spectrophotometry is a method used to analyze the total phosphorus content in water samples. In the prior art, the ammonium molybdate spectrophotometric method mainly includes the following steps: under neutral conditions, the sample is digested with potassium persulfate (or nitric acid-perchloric acid), and all the contained phosphorus is oxidized to orthophosphate. In acidic medium, orthophosphate reacts with ammonium molybdate to generate phosphomolybdenum heteropolyacid in the presence of antimony salt, which is immediately reduced by ascorbic acid to generate a blue complex solution. Then the content of phosphorus element in the blue complex solution was detected by spectrophotometry. [0003] However, duri...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N21/31
CPCG01N21/31
Inventor 吉军凯徐立
Owner 郑州市通标环境检测有限公司
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