CN114544533B - A quantitative detection method for low concentration urea in ultrapure water - Google Patents
A quantitative detection method for low concentration urea in ultrapure water Download PDFInfo
- Publication number
- CN114544533B CN114544533B CN202210169260.6A CN202210169260A CN114544533B CN 114544533 B CN114544533 B CN 114544533B CN 202210169260 A CN202210169260 A CN 202210169260A CN 114544533 B CN114544533 B CN 114544533B
- Authority
- CN
- China
- Prior art keywords
- concentration
- solution
- urea
- water sample
- reaction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/33—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using ultraviolet light
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/40—Concentrating samples
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/42—Low-temperature sample treatment, e.g. cryofixation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/28—Preparing specimens for investigation including physical details of (bio-)chemical methods covered elsewhere, e.g. G01N33/50, C12Q
- G01N1/44—Sample treatment involving radiation, e.g. heat
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/20—Controlling water pollution; Waste water treatment
Landscapes
- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Plasma & Fusion (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
- Investigating Or Analysing Materials By The Use Of Chemical Reactions (AREA)
Abstract
本发明公开了一种超纯水中低浓度尿素的定量检测方法，具体为：先对水样进行真空冷冻干燥处理；将真空冷冻干燥后的水样置于反应容器中，依次往管中加入二乙酰一肟溶液、稳定剂和催化剂，在管口密闭条件下将反应容器置于高温下进行反应；将反应后的反应液置于测量容器中，用分光光度计测定反应液的吸光度并根据标准曲线得到初始水样中尿素的浓度。本发明定量检测方法能够精确检测到水体中浓度为0.5～80ug/L的尿素；本发明方法先对含低浓度尿素水样进行真空冷冻干燥处理，再提高二乙酰一肟、安替比林/硫氨脲的浓度来增加反应后溶液的颜色，从而有效降低水体中尿素浓度的检测下限值；同时本发明方法通过加入金属离子来加速反应的进行以及增加显色的稳定性，使反应后的反应液在放置一段时间后，与0时吸光度相比，吸光度几乎无下降。
The invention discloses a quantitative detection method for low-concentration urea in ultrapure water, specifically: firstly subject a water sample to vacuum freeze drying treatment; placing the vacuum freeze-dried water sample in a reaction vessel, sequentially adding diacetyl monoxime solution, stabilizer and catalyst into the tube, placing the reaction vessel at high temperature under the condition of a closed tube mouth for reaction; placing the reaction solution after the reaction in a measuring container, measuring the absorbance of the reaction solution with a spectrophotometer and obtaining the concentration of urea in the initial water sample according to a standard curve. The quantitative detection method of the present invention can accurately detect urea with a concentration of 0.5 to 80ug/L in the water body; the method of the present invention first subject a water sample containing low-concentration urea to vacuum freeze drying treatment, and then increasing the concentration of diacetyl monoxime, antipyrine/thiocarbamide to increase the color of the solution after the reaction, thereby effectively reducing the detection lower limit of urea concentration in the water body; at the same time, the method of the present invention accelerates the reaction and increases the stability of color development by adding metal ions, so that the reaction solution after the reaction is placed for a period of time, and the absorbance is almost not reduced compared with the absorbance at 0.
Description
Technical Field
The invention relates to a quantitative detection method of low-concentration urea in ultrapure water.
Background
Urea is considered an important contaminant in the electronics industry for the production of ultra-pure water (UPW). Through actual water body detection and literature research, the content of urea in tap water is 10-30 ug/L, and the content of urea in reclaimed water is 40-100 ug/L. After tap water is treated by a conventional ultrapure water treatment system, the Total Organic Carbon (TOC) of the terminal effluent is less than 1ug/L, and the effluent standard is met. If reclaimed water is used, the terminal effluent often does not reach the standard, and urea has been proven to be one of the main reasons for the failure. In addition, urea releases ammonium upon heating, which can negatively impact the lithographic process. Therefore, it is necessary to develop a process for treating urea in reclaimed water, and embed the process into the tail end of the reclaimed water treatment, so as to reduce the concentration of urea in the effluent and enable the effluent of the treatment terminal to reach the standard. In the development process of new technology, the quantitative detection of urea is particularly important.
The national standard method (GB/T18204.2-2014) uses diacetyl monoxime-antipyrine spectrophotometry to detect urea, but the method can not accurately and quantitatively detect urea with the concentration below 5ug/L even after the concentration and the optical path of a color reagent are changed, and obviously can not meet the detection requirement of urea with the regenerated water level in the electronic industry.
Disclosure of Invention
The invention aims to provide a method capable of quantitatively detecting low-concentration urea in ultrapure water.
The quantitative detection method of the low-concentration urea in the ultrapure water comprises the steps of firstly carrying out vacuum freeze drying treatment on a water sample, placing the water sample subjected to vacuum freeze drying in a reaction container, sequentially adding diacetyl monooxime solution, a stabilizer and a catalyst into a pipe, placing the reaction container at a high temperature under the condition of sealing a pipe orifice for reaction, placing the reacted reaction liquid in a measurement container, measuring the absorbance of the reaction liquid by a spectrophotometer, and obtaining the concentration of urea in an initial water sample according to a standard curve.
The concentration of urea in the initial water sample is positively correlated with the concentration of the reaction product (diazine derivative), and the higher the concentration of urea, the more the reaction product.
Before the water sample is concentrated, the concentration of urea in the water sample is 0.3-0.5 ug/L, and after the vacuum freeze drying treatment, the concentration of urea in the water sample is 3-5 ug/L.
The vacuum freeze drying treatment comprises the steps of taking an initial water sample, placing the initial water sample in a closed container, pre-freezing the water sample for 6-24 hours at the temperature of minus 80 ℃ in a freezer, opening the container, placing the container in a vacuum freeze dryer for drying for 12-24 hours, placing the container at normal temperature after drying until ice cakes in the container are completely dissolved, and supplementing water (water with the same components as the initial water sample) into the liquid in a constant volume mode until the volume of the liquid is 1/10 of the volume of the initial water sample.
In the vacuum freeze drying process, the vacuum degree of the dryer is 0.05-0.06 MPa, and the temperature is-50 ℃.
Wherein the concentration of the diacetyl monooxime solution is 45 g/L-50 g/L.
The stabilizer is an antipyrine acid solution or a thiosemicarbazide acid solution, wherein the concentration of antipyrine in the antipyrine acid solution is 15 g/L-20 g/L, and the concentration of thiosemicarbazide in the thiosemicarbazide acid solution is 15 g/L-20 g/L.
The reaction of urea and diacetyl monooxime is carried out under an acidic condition, a large amount of sulfuric acid is added when antipyrine is prepared, and sulfate radical is added, so that more hydrogen ions exist in water when dissociation equilibrium is reached, and the acidic environment is enhanced.
Wherein the catalyst is sulfate containing cadmium ions and/or iron ions and/or silver ions.
Wherein, in the sulfate, the concentration of cadmium ions is 8g/L, the concentration of iron ions is 10g/L, and the concentration of silver ions is 8g/L.
Wherein, the reaction vessel is placed in boiling water bath under the condition of sealing the pipe orifice and heated for 30-50 min. The effect of heat on the reaction is to accelerate the progress of the reaction.
Wherein, the measuring container adopts a cuvette with the thickness of 5cm to measure. A 5cm cuvette was used to increase the optical path and thus the absorbance.
The saturated vapor pressure of urea is lower than that of water, water sublimates first due to the higher saturated vapor pressure, urea is less in hydrogen bond combined with water due to the lower concentration (under the environment with extremely high water molecule content, water molecules are more prone to self-clustering and are less combined with other substances, so that in the extremely low-concentration urea aqueous solution, the hydrogen bond combined between urea and water molecules is less, and most of the self-clustering between water molecules) and then sublimates. Therefore, on one hand, the concentration of the water sample can be realized by adopting the vacuum freeze drying treatment, and on the other hand, the loss of urea can not be caused in the vacuum freeze drying process, thereby ensuring the measurement accuracy.
The detection principle of the invention is that urea and diacetyl monooxime are condensed under the acid condition by catalysis of cadmium ions, ferric ions or silver ions to generate red diazine derivatives, the diazine derivatives are unstable to light (the diazine derivatives are easy to decompose under illumination and can decompose after long-term placement), so that the diazine derivatives need to react in a brown reaction vessel, and the cadmium ions, the ferric ions and the silver ions can improve the color development stability of the diazine derivatives besides the catalysis, namely, after metal ions and a stabilizer are added into a reaction system, the reacted diazine derivatives can not decompose even if placed for 24 hours.
The reaction equation of urea and diacetyl monooxime is:
Compared with the prior art, the quantitative detection method has the advantages that urea with the concentration of 0.3-80 ug/L in the water body can be accurately detected, the method firstly carries out vacuum freeze-drying treatment on a water sample containing low-concentration urea, then improves the concentration of diacetyl oxime and antipyrine/thiosemicarbazide to increase the color of a solution after reaction, so that the detection lower limit value of the concentration of urea in the water body is effectively reduced, and meanwhile, the method accelerates the reaction and increases the color development stability by adding metal ions, so that the absorbance of the reacted reaction solution is almost not reduced compared with the absorbance at 0 time after the reaction solution is placed for a period of time.
Drawings
FIG. 1 is a graph of urea standard solution in an example.
Detailed Description
Example 1
The invention relates to a quantitative detection method of low-concentration urea in ultrapure water, which specifically comprises the following steps:
Step (1), taking 250mL of initial water sample, putting the initial water sample into a polytetrafluoroethylene plastic bottle, screwing a bottle cap, taking out the bottle cap after pre-freezing for 24 hours in a freezer at the temperature of-80 ℃, unscrewing the bottle cap, putting the polytetrafluoroethylene plastic bottle into a vacuum freeze-dryer, drying for 24 hours, taking out the polytetrafluoroethylene plastic bottle after drying, standing at normal temperature until ice cakes in the polytetrafluoroethylene plastic bottle are completely dissolved, supplementing water (water with the same components as the initial water sample) into the liquid in a constant volume mode until the volume of the liquid is 1/10 (25 mL) of the volume of the initial water sample, keeping the vacuum degree of the dryer at 0.05MPa and the temperature of-50 ℃, keeping the urea concentration in the initial water sample at 0.3ug/L, and keeping the urea concentration in the water sample at 3ug/L after the vacuum freeze-drying treatment;
preparing diacetyl monooxime solution with the concentration of 50g/L, namely weighing 5g of diacetyl monooxime, dissolving in 10mL of isopropanol, stirring until the diacetyl monooxime is completely dissolved, diluting the solution with 10 mass percent of isopropanol until the volume of the solution is 100mL, and storing the solution in a brown bottle at normal temperature;
Preparing an acid solution with the antipyrine concentration of 15g/L, specifically, weighing 1.5g antipyrine, dissolving in mixed acid (the mixed acid is composed of sulfuric acid and phosphoric acid in a volume ratio of 9:1), adding water to a volume of 100mL, and preserving in a brown bottle for later use;
step (4) preparing a silver sulfate solution with the concentration of 8g/L, namely weighing 0.8g of silver sulfate, dissolving in 50vol.% sulfuric acid, adding water to a volume of 100mL, and storing in a brown bottle for later use;
Step (5), digestion and color development, namely weighing 25mL of the water sample concentrated in the step 1, putting the water sample into a 50mL brown colorimetric tube, sequentially adding 2mL of diacetyl monoxime solution, 2mL of antipyrine acid solution and 1mL of silver sulfate solution into the colorimetric tube, tightly tying a tube orifice with a raw rubber belt, putting the tube orifice into a boiling water bath, heating for 50min, taking out a standing horse, and cooling in flowing tap water (the cooling purpose is that the cooling needs to be performed at room temperature in the measurement of the next step) for 2min;
and (6) measuring the absorbance of the reaction liquid after the reaction by using a cuvette with the wavelength of 5cm at 460nm, and obtaining the concentration of urea in the initial water sample according to a standard curve, wherein the absorbance value can still be detected when the concentration of urea in the initial water sample is 0.3ug/L and the concentration of urea in the water sample is 3ug/L after the vacuum freeze drying treatment.
The establishment of a standard curve, namely, respectively weighing 25mL of urea standard solution with the concentration of 0.01mg/L, 0.02mg/L, 0.03mg/L, 0.04mg/L, 0.05mg/L, 0.06mg/L, 0.07mg/L and 0.08mg/L in a 50mL brown color comparison tube, sequentially adding 2mL of diacetyl monoxime solution (50 g/L diacetyl monoxime solution), 2mL of antipyrine acid solution (antipyrine acid solution with the concentration of 15 g/L) and 1mL of silver sulfate solution (8 g/L silver sulfate solution) into the color comparison tube, and carrying out the steps (5) and (6) to obtain a urea standard solution graph. And (3) using a standard solution graph to obtain the concentration of urea in the initial water sample quickly after obtaining the light absorption value under the same concentration of reactant.
As shown in FIG. 1, the relation between the urea concentration and the absorbance within 0-80 ug/L accords with beer's law, the linear regression equation is y= 1.0058x-0.0032, the correlation coefficient r= 0.9991, and the correlation of the standard curve accords with the requirement.
Comparative example 1
The urea quantitative detection method specifically comprises the following steps:
Step (1), taking 250mL of initial water sample, putting the initial water sample into a polytetrafluoroethylene plastic bottle, screwing a bottle cap, taking out the bottle cap after pre-freezing for 24 hours in a freezer at the temperature of-80 ℃, unscrewing the bottle cap, putting the polytetrafluoroethylene plastic bottle into a vacuum freeze-dryer, drying for 24 hours, taking out the polytetrafluoroethylene plastic bottle after drying, standing at normal temperature until ice cakes in the polytetrafluoroethylene plastic bottle are completely dissolved, supplementing water (water with the same components as the initial water sample) into the liquid in a constant volume mode until the volume of the liquid is 1/10 (25 mL) of the volume of the initial water sample, keeping the vacuum degree of the dryer at 0.05MPa and the temperature of-50 ℃, keeping the urea concentration in the initial water sample at 0.3ug/L, and keeping the urea concentration in the water sample at 3ug/L after the vacuum freeze-drying treatment;
preparing diacetyl monooxime solution with the concentration of 50g/L, namely weighing 5g of diacetyl monooxime, dissolving in 10mL of isopropanol, stirring until the diacetyl monooxime is completely dissolved, diluting the solution with 10 mass percent of isopropanol until the volume of the solution is 100mL, and storing the solution in a brown bottle at normal temperature;
Preparing an acid solution with the antipyrine concentration of 15g/L, specifically, weighing 1.5g antipyrine, dissolving in mixed acid (the mixed acid is composed of sulfuric acid and phosphoric acid in a volume ratio of 9:1), adding water to a volume of 100mL, and preserving in a brown bottle for later use;
Step (4), preparing a silver sulfate solution with the concentration of 8g/L, weighing 0.8g of silver sulfate, dissolving in 50vol.% sulfuric acid, adding water to a volume of 100mL, and storing in a brown bottle for later use;
Step (5), digestion and color development, namely weighing 25mL of the water sample concentrated in the step 1, putting the water sample into a 50mL brown colorimetric tube, sequentially adding 2mL of diacetyl monooxime solution and 2mL of antipyrine acid solution into the colorimetric tube, fastening a tube orifice with a raw rubber belt, putting the tube orifice into a boiling water bath, heating for 80min, taking out a vertical horse, and cooling in flowing tap water (the cooling purpose is that the cooling needs to be performed at room temperature in the next measurement) for 2min;
and (6) measuring by an ultraviolet spectrophotometer, using a cuvette with the wavelength of 460nm and 5cm, measuring the absorbance of the reaction liquid after the reaction, and obtaining the concentration of urea in the initial water sample according to a standard curve.
After 24 hours, the absorbance of the reaction solutions of example 1 and comparative example 1 was again measured, and the absorbance of comparative example 1 to which no metal ion was added was decreased by 12.15% (this absorbance was compared with time 0), whereas the absorbance of example 1 to which a metal ion was added was decreased by only 3%. While the heating time of comparative example 1, in which no metal ion was added, also increased significantly.
Comparative example 2
The urea quantitative detection method specifically comprises the following steps:
The method comprises the steps of (1) preparing diacetyl monooxime solution with the concentration of 50g/L, specifically, weighing 5g of diacetyl monoxime, dissolving in 10mL of isopropanol, stirring until the diacetyl monoxime is completely dissolved, diluting the solution with 10% of isopropanol by mass fraction until the volume of the solution is 100mL, and storing the solution in a brown bottle at normal temperature;
Preparing an acid solution with the antipyrine concentration of 15g/L, specifically, weighing 1.5g antipyrine, dissolving in mixed acid (the mixed acid is composed of sulfuric acid and phosphoric acid in a volume ratio of 9:1), adding water to a volume of 100mL, and preserving in a brown bottle for later use;
Preparing a silver sulfate solution with the concentration of 8g/L, weighing 0.8g of silver sulfate, dissolving in 50vol.% sulfuric acid, adding water to a volume of 100mL, and storing in a brown bottle for later use;
Step (4), digestion and color development, namely weighing 25mL of water sample into a 50mL brown colorimetric tube, sequentially adding 4mL of diacetyl monooxime solution, 4mL of antipyrine acid solution and 1mL of silver sulfate solution into the colorimetric tube, fastening a tube orifice with a raw rubber belt, putting into a boiling water bath, heating for 50min, taking out a vertical horse, and cooling in flowing tap water (the cooling purpose is that in the next measurement, the cooling needs to be performed at room temperature) for 2min;
And (5) measuring by an ultraviolet spectrophotometer, using a cuvette with the wavelength of 460nm and 5cm, measuring the absorbance of the reaction liquid after the reaction, and obtaining the concentration of urea in the initial water sample according to a standard curve.
The establishment of a standard curve, namely, respectively weighing 25mL of urea standard solution with the concentration of 0.01mg/L, 0.02mg/L, 0.03mg/L, 0.04mg/L, 0.05mg/L, 0.06mg/L, 0.07mg/L and 0.08mg/L in a 50mL brown color comparison tube, sequentially adding 4mL of diacetyl monoxime solution (50 g/L diacetyl monoxime solution), 4mL of antipyrine acid solution (antipyrine acid solution with the concentration of 15 g/L) and 1mL of silver sulfate solution (8 g/L silver sulfate solution) into the color comparison tube, and carrying out the steps (5) and (6) to obtain a urea standard solution graph. And (3) using a standard solution graph to obtain the concentration of urea in the initial water sample quickly after obtaining the light absorption value under the same concentration of reactant.
The lower limit of detection in comparative example 2 was 5ug/L (no absorbance value when the urea concentration in the water sample was lower than 5 ug/L), and the measurement range was 5 to 80ug/L, which indicates that even if the reaction concentration of the reaction reagent was increased in comparative example 2, the water sample with urea concentration of 5ug/L or lower could not be quantitatively detected.
Comparative example 3
The urea quantitative detection method specifically comprises the following steps:
Step (1), taking 250mL of initial water sample, putting the initial water sample into a polytetrafluoroethylene plastic bottle, screwing a bottle cap, taking out the bottle cap after pre-freezing for 24 hours in a freezer at the temperature of-80 ℃, unscrewing the bottle cap, putting the polytetrafluoroethylene plastic bottle into a vacuum freeze-dryer, drying for 24 hours, taking out the polytetrafluoroethylene plastic bottle after drying, standing at normal temperature until ice cakes in the polytetrafluoroethylene plastic bottle are completely dissolved, supplementing water (water with the same components as the initial water sample) into the liquid in a constant volume mode until the volume of the liquid is 1/10 (25 mL) of the volume of the initial water sample, keeping the vacuum degree of the dryer at 0.05MPa and the temperature of-50 ℃, keeping the urea concentration in the initial water sample at 0.3ug/L, and keeping the urea concentration in the water sample at 3ug/L after the vacuum freeze-drying treatment;
preparing diacetyl monooxime solution with the concentration of 50g/L, namely weighing 5g of diacetyl monooxime, dissolving in 10mL of isopropanol, stirring until the diacetyl monooxime is completely dissolved, diluting the solution with 10 mass percent of isopropanol until the volume of the solution is 100mL, and storing the solution in a brown bottle at normal temperature;
Preparing an acid solution with the antipyrine concentration of 15g/L, specifically, weighing 1.5g antipyrine, dissolving in mixed acid (the mixed acid is composed of sulfuric acid and phosphoric acid in a volume ratio of 9:1), adding water to a volume of 100mL, and preserving in a brown bottle for later use;
Step (4), preparing a silver sulfate solution with the concentration of 8g/L, weighing 0.8g of silver sulfate, dissolving in 50vol.% sulfuric acid, adding water to a volume of 100mL, and storing in a brown bottle for later use;
Step (5), digestion and color development, namely weighing 25mL of the water sample concentrated in the step 1, putting the water sample into a 50mL colorless colorimetric tube, sequentially adding 2mL of diacetyl monoxime solution, 2mL of antipyrine acid solution and 1mL of silver sulfate solution into the colorimetric tube, tightly tying a tube orifice with a raw rubber belt, putting the tube orifice into a boiling water bath, heating for 50min, taking out a standing horse, and cooling in flowing tap water (the cooling purpose is that the cooling needs to be performed at room temperature in the measurement of the next step) for 2min;
and (6) measuring by an ultraviolet spectrophotometer, using a cuvette with the wavelength of 460nm and 5cm, measuring the absorbance of the reaction liquid after the reaction, and obtaining the concentration of urea in the initial water sample according to a standard curve.
The absorbance of the reaction solutions of comparative example 1 and comparative example 3 was found to be 3.15% lower in the measured value of the reaction with a colorless cuvette than in the measurement value of the reaction with a brown cuvette, within the error range specified by the standard. It can be stated that, after addition of the metal ions, the color stability of the reaction product is increased, and that a transparent cuvette can be used instead of a brown cuvette.
Comparative example 4
The urea quantitative detection method specifically comprises the following steps:
Step (1), taking 250mL of initial water sample, putting the initial water sample into a polytetrafluoroethylene plastic bottle, screwing a bottle cap, taking out the bottle cap after pre-freezing for 24 hours in a freezer at the temperature of-80 ℃, unscrewing the bottle cap, putting the polytetrafluoroethylene plastic bottle into a vacuum freeze-dryer, drying for 24 hours, taking out the polytetrafluoroethylene plastic bottle after drying, standing at normal temperature until ice cakes in the polytetrafluoroethylene plastic bottle are completely dissolved, supplementing water (water with the same components as the initial water sample) into the liquid in a constant volume mode until the volume of the liquid is 1/10 (25 mL) of the volume of the initial water sample, keeping the vacuum degree of the dryer at 0.05MPa and the temperature of-50 ℃, keeping the urea concentration in the initial water sample at 0.3ug/L, and keeping the urea concentration in the water sample at 3ug/L after the vacuum freeze-drying treatment;
preparing diacetyl monooxime solution with the concentration of 50g/L, namely weighing 5g of diacetyl monooxime, dissolving in 10mL of isopropanol, stirring until the diacetyl monooxime is completely dissolved, diluting the solution with 10 mass percent of isopropanol until the volume of the solution is 100mL, and storing the solution in a brown bottle at normal temperature;
Preparing an acid solution with the antipyrine concentration of 15g/L, specifically, weighing 1.5g antipyrine, dissolving in mixed acid (the mixed acid is composed of sulfuric acid and phosphoric acid in a volume ratio of 9:1), adding water to a volume of 100mL, and preserving in a brown bottle for later use;
Step (4), preparing a silver sulfate solution with the concentration of 8g/L, weighing 0.8g of silver sulfate, dissolving in 50vol.% sulfuric acid, adding water to a volume of 100mL, and storing in a brown bottle for later use;
Step (5), digestion and color development, namely weighing 25mL of the water sample concentrated in the step 1, putting the water sample into a 50mL brown colorimetric tube, sequentially adding 2mL of diacetyl monoxime solution, 2mL of antipyrine acid solution and 1mL of silver sulfate solution into the colorimetric tube, tightly tying a tube orifice with a raw rubber belt, putting the tube orifice into a boiling water bath, heating for 30min, taking out a standing horse, and cooling in flowing tap water (the cooling purpose is that the cooling needs to be performed at room temperature in the measurement of the next step) for 2min;
and (6) measuring by an ultraviolet spectrophotometer, using a cuvette with the wavelength of 460nm and 5cm, measuring the absorbance of the reaction liquid after the reaction, and obtaining the concentration of urea in the initial water sample according to a standard curve.
The absorbance of the reaction solutions of comparative example 1 and comparative example 4 was found to be 2.89% lower than the measured value of the reaction for 50min for 30min after the addition of the metal ion, within the error range prescribed by the standard. It can be demonstrated that the reaction proceeds with acceleration after the addition of the metal ions, resulting in a 20min reduction in the reaction time.
Example 2
The invention relates to a quantitative detection method of low-concentration urea in ultrapure water, which specifically comprises the following steps:
Step (1), taking 250mL of initial water sample, putting the initial water sample into a polytetrafluoroethylene plastic bottle, screwing a bottle cap, taking out the bottle cap after pre-freezing for 24 hours in a freezer at the temperature of-80 ℃, unscrewing the bottle cap, putting the polytetrafluoroethylene plastic bottle into a vacuum freeze-dryer, drying for 24 hours, taking out the polytetrafluoroethylene plastic bottle after drying, standing at normal temperature until ice cakes in the polytetrafluoroethylene plastic bottle are completely dissolved, supplementing water (water with the same components as the initial water sample) into the liquid in a constant volume mode until the volume of the liquid is 1/10 (25 mL) of the volume of the initial water sample, keeping the vacuum degree of the dryer at 0.05MPa and the temperature of-50 ℃, keeping the urea concentration in the initial water sample at 0.4ug/L, and keeping the urea concentration in the water sample at 4ug/L after the vacuum freeze-drying treatment;
preparing diacetyl monooxime solution with the concentration of 50g/L, namely weighing 5g of diacetyl monooxime, dissolving in 10mL of isopropanol, stirring until the diacetyl monooxime is completely dissolved, diluting the solution with 10 mass percent of isopropanol until the volume of the solution is 100mL, and storing the solution in a brown bottle at normal temperature;
Preparing an acid solution with the concentration of the thiosemicarbazide of 15g/L, specifically, weighing 1.5g of the thiosemicarbazide, dissolving the solution in mixed acid (the mixed acid is composed of sulfuric acid and phosphoric acid in a volume ratio of 9:1), adding water to a volume of 100mL, and preserving the solution in a brown bottle for later use;
step (4), preparing a cadmium sulfate solution with the concentration of 8g/L, weighing 0.8g of cadmium sulfate, dissolving in 50vol.% sulfuric acid, adding water to a volume of 100mL, and storing in a brown bottle for later use;
Step (5), digestion and color development, namely weighing 25mL of the water sample concentrated in the step 1, putting the water sample into a 50mL brown color comparison tube, sequentially adding 2mL of diacetyl monoxime solution, 2mL of thiosemicarbazide acid solution and 1mL of cadmium sulfate solution into the color comparison tube, tightly tying a tube orifice with a rubber belt, putting the tube orifice into a boiling water bath, heating for 30min, taking out a standing horse, and cooling in flowing tap water (the cooling purpose is that the cooling needs to be performed at room temperature in the next measurement) for 2min;
And (6) measuring by an ultraviolet spectrophotometer, measuring the absorbance of the reaction liquid after the reaction by a cuvette with the wavelength of 5cm at 460nm, obtaining the concentration of urea in the initial water sample according to a standard curve, wherein the absorbance value can still be detected when the concentration of urea in the initial water sample is 0.4ug/L and the concentration of urea in the water sample is 4ug/L after the vacuum freeze drying treatment.
The establishment of a standard curve, namely respectively weighing 25mL of urea standard solution with the concentration of 0.01mg/L, 0.02mg/L, 0.03mg/L, 0.04mg/L, 0.05mg/L, 0.06mg/L, 0.07mg/L and 0.08mg/L in a 50mL brown color comparison tube, sequentially adding 2mL of diacetyl monoxime solution, 2mL of thiosemicarbazide acid solution and 1mL of cadmium sulfate solution into the color comparison tube, and carrying out the step (5) and the step (6) to obtain a urea standard solution curve graph. And (3) obtaining the concentration of urea in the initial water sample quickly after obtaining the light absorption value by using a standard solution graph under the condition of a reactant with a corresponding concentration.
Example 3
The invention relates to a quantitative detection method of low-concentration urea in ultrapure water, which specifically comprises the following steps:
step (1), taking 250mL of initial water sample, putting the initial water sample into a polytetrafluoroethylene plastic bottle, screwing a bottle cap, taking out the bottle cap after pre-freezing for 24 hours in a freezer at the temperature of-80 ℃, unscrewing the bottle cap, putting the polytetrafluoroethylene plastic bottle into a vacuum freeze-dryer, drying for 24 hours, taking out the polytetrafluoroethylene plastic bottle after drying, standing at normal temperature until ice cakes in the polytetrafluoroethylene plastic bottle are completely dissolved, supplementing water (water with the same components as the initial water sample) into the liquid in a constant volume mode until the volume of the liquid is 1/10 (25 mL) of the volume of the initial water sample, keeping the vacuum degree of the dryer at 0.05MPa and the temperature of-50 ℃, keeping the urea concentration in the initial water sample at 0.5ug/L, and keeping the urea concentration in the water sample at 5ug/L after the vacuum freeze-drying treatment;
preparing diacetyl monooxime solution with the concentration of 50g/L, namely weighing 5g of diacetyl monooxime, dissolving in 10mL of isopropanol, stirring until the diacetyl monooxime is completely dissolved, diluting the solution with 10 mass percent of isopropanol until the volume of the solution is 100mL, and storing the solution in a brown bottle at normal temperature;
Preparing an acid solution with the antipyrine concentration of 15g/L, specifically, weighing 1.5g antipyrine, dissolving in mixed acid (the mixed acid is composed of sulfuric acid and phosphoric acid in a volume ratio of 9:1), adding water to a volume of 100mL, and preserving in a brown bottle for later use;
Preparing an iron sulfate solution with the concentration of 10g/L, weighing 1.0g of iron sulfate, dissolving in 50vol.% sulfuric acid, adding water to a volume of 100mL, and storing in a brown bottle for later use;
Step (5), digestion and color development, namely weighing 25mL of the water sample concentrated in the step 1, putting the water sample into a 50mL brown colorimetric tube, sequentially adding 2mL of diacetyl monoxime solution, 2mL of antipyrine acid solution and 1mL of ferric sulfate solution into the colorimetric tube, tightly tying a tube orifice with a raw rubber belt, putting the tube orifice into a boiling water bath, heating for 50min, taking out a standing horse, and cooling in flowing tap water (the cooling purpose is that the cooling needs to be performed at room temperature in the measurement of the next step) for 2min;
And (6) measuring the absorbance of the reaction liquid after the reaction by using a cuvette with the wavelength of 5cm at 460nm, and obtaining the concentration of urea in the initial water sample according to a standard curve, wherein the absorbance value can still be detected when the concentration of urea in the initial water sample is 0.5ug/L and the concentration of urea in the water sample is 5ug/L after the vacuum freeze drying treatment.
The establishment of a standard curve, namely, respectively weighing 25mL of urea standard solution with the concentration of 0.01mg/L, 0.02mg/L, 0.03mg/L, 0.04mg/L, 0.05mg/L, 0.06mg/L, 0.07mg/L and 0.08mg/L in a 50mL brown color comparison tube, sequentially adding 2mL of diacetyl monoxime solution (50 g/L diacetyl monoxime solution), 2mL of antipyrine acid solution (antipyrine acid solution with the concentration of 15 g/L) and 1mL of ferric sulfate solution (10 g/L silver sulfate solution) into the color comparison tube, and carrying out the steps (5) and (6) to obtain a urea standard solution graph. And (3) obtaining the concentration of urea in the initial water sample quickly after obtaining the light absorption value by using a standard solution graph under the condition of a reactant with a corresponding concentration.
Claims (1)
1. The quantitative detection method of the urea with low concentration in the ultrapure water is characterized by comprising the following steps:
Step (1), taking 250mL of initial water sample, putting the initial water sample into a polytetrafluoroethylene plastic bottle, screwing a bottle cap, taking out the bottle cap after pre-freezing for 24 hours in a freezer at the temperature of-80 ℃, unscrewing the bottle cap, putting the polytetrafluoroethylene plastic bottle into a vacuum freeze-drying instrument, drying for 24 hours, taking out the polytetrafluoroethylene plastic bottle after drying, placing the polytetrafluoroethylene plastic bottle at normal temperature until ice cakes therein are completely dissolved, supplementing water with the same components as the initial water sample into the liquid in a constant volume mode until the liquid volume is 1/10 of the volume of the initial water sample, ensuring that the vacuum degree of the dryer is 0.05MPa, the temperature is-50 ℃, ensuring that the urea concentration in the initial water sample is 0.3 mu g/L, and ensuring that the urea concentration in the water sample is 3 mu g/L after the vacuum freeze-drying treatment;
Preparing diacetyl monooxime solution with the concentration of 50g/L, namely weighing 5g of diacetyl monooxime, dissolving in 10mL of isopropanol, stirring until the diacetyl monooxime is completely dissolved, diluting the solution with 10 mass percent of isopropanol until the volume of the solution is 100mL, and storing the solution in a brown bottle at normal temperature;
Preparing an acid solution with the concentration of antipyrine of 15g/L, namely weighing 1.5g of antipyrine, dissolving in mixed acid, adding water to a volume of 100mL, and storing in a brown bottle for later use, wherein the mixed acid consists of sulfuric acid and phosphoric acid in a volume ratio of 9:1;
step (4) preparing a silver sulfate solution with the concentration of 8g/L, namely weighing 0.8g of silver sulfate, dissolving in 50vol.% sulfuric acid, adding water to a volume of 100mL, and storing in a brown bottle for later use;
Step (5), digestion and color development, namely weighing 25mL of the water sample concentrated in the step 1, putting the water sample into a 50mL brown colorimetric tube, sequentially adding 2mL of diacetyl monooxime solution, 2mL of antipyrine acid solution and 1mL of silver sulfate solution into the colorimetric tube, tightly tying a tube orifice with a raw rubber belt, putting the tube orifice into a boiling water bath, heating for 50min, taking out a standing horse, and cooling in flowing tap water for 2min;
And (6) measuring the absorbance of the reaction liquid after the reaction by using a cuvette with the wavelength of 5cm at 460nm, and obtaining the concentration of urea in the initial water sample according to a standard curve.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210169260.6A CN114544533B (en) | 2022-02-23 | 2022-02-23 | A quantitative detection method for low concentration urea in ultrapure water |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202210169260.6A CN114544533B (en) | 2022-02-23 | 2022-02-23 | A quantitative detection method for low concentration urea in ultrapure water |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114544533A CN114544533A (en) | 2022-05-27 |
| CN114544533B true CN114544533B (en) | 2025-02-14 |
Family
ID=81677265
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202210169260.6A Active CN114544533B (en) | 2022-02-23 | 2022-02-23 | A quantitative detection method for low concentration urea in ultrapure water |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114544533B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115308149A (en) * | 2022-08-05 | 2022-11-08 | 江苏丰华生物制药有限公司 | A kind of method that utilizes ultraviolet-visible spectrophotometry to measure urea residue in tenecteplase |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4040787A (en) * | 1976-04-21 | 1977-08-09 | The Dow Chemical Company | Urea determination of biological fluids using diacetylmonoxime reaction |
| JPS59111052A (en) * | 1982-12-17 | 1984-06-27 | Jeol Ltd | Liquid sample concentration introduction device |
| CN111487209A (en) * | 2020-04-06 | 2020-08-04 | 浙江信捷检测技术有限公司 | Method for measuring concentration of urea in swimming pool water |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108132251A (en) * | 2017-12-19 | 2018-06-08 | 江苏康达检测技术股份有限公司 | The assay method of urea concentration in a kind of water |
-
2022
- 2022-02-23 CN CN202210169260.6A patent/CN114544533B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4040787A (en) * | 1976-04-21 | 1977-08-09 | The Dow Chemical Company | Urea determination of biological fluids using diacetylmonoxime reaction |
| JPS59111052A (en) * | 1982-12-17 | 1984-06-27 | Jeol Ltd | Liquid sample concentration introduction device |
| CN111487209A (en) * | 2020-04-06 | 2020-08-04 | 浙江信捷检测技术有限公司 | Method for measuring concentration of urea in swimming pool water |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114544533A (en) | 2022-05-27 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN114544533B (en) | A quantitative detection method for low concentration urea in ultrapure water | |
| CN106770729A (en) | A kind of method for detecting free state and combining state micro cyanide | |
| US11312625B2 (en) | Hydrogen sulfide mixture, method for producing same, and filling container | |
| US20160054228A1 (en) | Total nitrogen measurement apparatus | |
| Tašev et al. | Determination of inorganic and total arsenic in wines by hydride generation atomic absorption spectrometry | |
| CN103411959A (en) | Method for directly measuring total nitrogen content in solution | |
| CN111044670A (en) | Cation exchange capacity test method for ammonium type and ammonium type mixed powder ion exchange resin | |
| CN107703072A (en) | The correction assay method of total cyanide in a kind of thiocyanate water quality | |
| CN102408099A (en) | Device and method suitable for extracting acid volatile sulfides in sediments | |
| CN102507554A (en) | Method for detecting beryllium content in water | |
| CN112229802B (en) | Method for quantifying concentration of nitrite nitrogen and nitrous acid in nitrooxidant wastewater | |
| Kiba et al. | Microcolorimetric Determination of Sulfate by Reduction to Hydrogen Sulfide with Tin (II)—Strong Phosphoric Acid | |
| TWI850428B (en) | Method for producing urea-free water, method for quantifying urea, and urea analysis device | |
| CA1117403A (en) | Process for the quantitative determination of the carbon of organic compounds in water | |
| CN108341452B (en) | A method for coupling membrane separation process and chemical deoxidation process to remove dissolved oxygen in water | |
| CN114920405B (en) | A high-efficiency deamination device and method for leachate AnMBR effluent from waste incineration plants | |
| CN113391026B (en) | A kind of rapid distillation method and detection method of sulfur dioxide | |
| CN212301343U (en) | Quantitative test device for ammonia nitrogen substances in fly ash | |
| Collins et al. | Lithium Chloride and Ammonia Complexes | |
| CN111751363A (en) | Quantitative testing device and testing method for ammonia nitrogen substances in fly ash | |
| Cade | Photometric Determination of Fluosilicic Acid in Hydrofluoric Acid | |
| CN115728443B (en) | Method for measuring cyanide ions in complex water quality | |
| CN105060553B (en) | A kind of processing method of formaldehyde waste water | |
| CN106053746A (en) | Method for Determination of Chemical Oxygen Demand of High Chlorine Wastewater After Electrolytic Treatment | |
| Yan Kai et al. | Research and improvement of national standard detection method for phosphorus in food. |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |