Method for determining phosphate with ammonium molybdate spectrophotometry

Abstract

A method for determining phosphate with ammonium molybdate spectrophotometry comprises the steps as follows: a standard solution and a reagent are firstly prepared, then sampling is performed and a sample is treated; next, 0.05 ml, 0.25 ml, 0.5 ml, 1.0 ml, 1.50 ml and 2.0 ml of phosphoric acid standard solutions are added to 6 volumetric flasks, water is added, and 0.05 ug, 2.5 ug, 5.0 ug, 10.0 ug, 15.0 ug and 20.0 ug of phosphoric acid standard series are prepared; sulfuric acid, ammonium molybdate and ascorbic acid solutions are added to standard tubes respectively, water is added until thestandard tubes reach the constant volume, the solutions are taken out after being heated in a boiling water bath and cooled to the room temperature, the absorbance is measured at the wavelength of 680nm, each concentration is repeatedly determined 3 times, and a standard curve is drawn for corresponding phosphoric acid according to the absorbance mean value; eluents of the sample and a blank control are determined, the content of the phosphoric acid is obtained through the standard curve after the measured absorbance value of the sample subtracts the absorbance value of the blank control, andfinally, the concentration of phosphate in standard gas is calculated. Reducing agent hydrazine sulfate is replaced with ascorbic acid, the defect of poor hydrazine sulfate developing effect is madeup by use of the advantage of the good developing effect of ascorbic acid serving as an indicator, and the accuracy of the detection result is improved.

Description

Technical field [0001] The invention belongs to the technical field of occupational hygiene detection, and relates to a method for measuring the concentration of inorganic phosphorus-containing compounds in the air of a workplace, and aims to protect the health of workers in workplaces containing inorganic phosphorus-containing compounds. Background technique [0002] In some special workplaces, the air may contain inorganic phosphorus compounds, which can cause harm to the human body. Therefore, it is very important to detect and monitor the concentration of inorganic phosphorus compounds in the workplace air. The prior art method for measuring the concentration of inorganic phosphorus-containing compounds in the air of the workplace is to wear a small plastic sampling clip with a microporous filter membrane on the upper part of the chest of the sampling object at the sampling point to collect the air sample. Fold the membrane in half twice with the dust-receiving side inward, a...

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Problems solved by technology

In the above method, hydrazine sulfate is used as a reducing agent, and the color rendering effect is not good in the test, resulting in

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