CN100390539C - Analytical method when formaldehyde, methanol and N,N-dimethylhydroxylamine coexist - Google Patents

Abstract

The invention relates to an analysis method when formaldehyde, methanol and N,N-dimethylhydroxylamine coexist, and belongs to the technical field of organic chemical analysis. The analysis method of the present invention adopts the gas chromatographic method combined with GCX-401 packed column (φ3mm×2m) and hydrogen flame ionization detector to analyze formaldehyde, methanol and N,N-dimethylhydroxylamine rapidly qualitatively and quantitatively simultaneously. The analysis method of the present invention has short analysis time, high speed, simple and convenient operation, high analysis accuracy, and can quickly analyze formaldehyde, methanol and N,N-dimethylhydroxylamine when coexisting.

Description

Analytical method when formaldehyde, methanol and N,N-dimethylhydroxylamine coexist

technical field

The invention relates to a qualitative and quantitative analysis method when formaldehyde, methanol and N,N-dimethylhydroxylamine coexist, and belongs to the technical field of organic chemical analysis.

Background technique

With the development of nuclear power industry, the reprocessing of nuclear fuel has attracted widespread attention. N, N-dimethylhydroxylamine is a new salt-free reducing agent that is expected to be used in nuclear fuel reprocessing. However, the reprocessing of spent fuel is carried out in a strong radiation environment. Under this condition, N,N-dimethylhydroxylamine will undergo radiolysis, and the organic substances produced by radiolysis may be formaldehyde, methanol, formic acid and nitric acid. ethane, these organics may affect the separation of nuclear fuel. Therefore, it is necessary to analyze the composition and content of organic matter in the solution after N,N-dimethylhydroxylamine irradiation, so as to provide an important reference for the application of N,N-dimethylhydroxylamine in post-treatment. At first, the gas chromatographic method with high separation efficiency PEG-20M capillary column and highly sensitive hydrogen flame ionization detector is used to qualitatively analyze the solution after the irradiation of N, N-dimethylhydroxylamine aqueous solution. The results show that there is only Methanol, formaldehyde and N,N-dimethylhydroxylamine, no formic acid and nitromethane. Since the hydrogen flame ionization detector has little effect on formaldehyde, if a capillary column is used, the response will be smaller and the quantitative error will be large, so it is hoped to use a packed column for quantitative analysis. The analysis of formaldehyde and methanol has been reported by gas chromatography and chemical methods; the analysis of N,N-dimethylhydroxylamine has also been reported by ion chromatography. However, the analysis of the coexistence of formaldehyde, methanol and N, N-diethylhydroxylamine has not been reported.

Contents of the invention

The purpose of this invention is to provide a kind of rapid qualitative and quantitative analysis formaldehyde, methyl alcohol and N, the method for N-dimethyl hydroxylamine simultaneously. The invention adopts GDX-401 packed column and hydrogen flame ionization detector to qualitatively and quantitatively analyze the formaldehyde, methanol and N,N-dimethylhydroxylamine produced by radiolysis of N,N-dimethylhydroxylamine aqueous solution.

The present invention is a kind of analytical method when formaldehyde, methyl alcohol and N, N-dimethyl hydroxylamine coexist, it is characterized in that having following analysis process and step:

a. Prepare simulated samples: prepare a mixed solution containing formaldehyde, methanol and N,N-dimethylhydroxylamine;

b. Adopt the gas chromatography method of GDX-401 packed column of φ3mm×2m combined with hydrogen flame ionization detector, put the GDX-401 packed column into the chromatograph correctly, pass nitrogen gas, and adjust its flow rate to 20ml/min, After 20 minutes, ventilate the air and adjust its flow rate to 300ml/min; set the column temperature to 130°C, set the vaporization chamber temperature to 160°C, and the detector temperature to 160°C; set the gain to 10 ⁹ and the attenuation to zero ;Operating column temperature, gasification chamber and detector temperature;

c. When the hydrogen flame ionization detector reaches the set temperature of 160°C, pass hydrogen gas and adjust the flow rate of hydrogen gas to 80ml/min. Use an electronic ignition gun to ignite at the outlet of the detector, and then slowly reduce the hydrogen flow rate to 20ml/min;

d. Turn on the button of the N2000 chromatographic data workstation converter, turn on the computer, enter the online workstation, select the detector channel, input the appropriate text and parameters, select "data acquisition", set zero, and take the baseline;

e. When the baseline is stable, use an airtight medical syringe to extract 1.0 microliters of the prepared mixed solution simulation sample, and quickly inject it into the gas chromatograph, and press the remote control button of the corresponding channel at the same time;

f. After the sampling analysis is finished, that is, after the peak is finished, press the stop sampling button; then enter the qualitative analysis and quantitative analysis stages; the qualitative analysis uses the retention time control method; the quantitative analysis uses the external standard method, that is, quantitative sampling - working curve Quantitative sampling - working curve method is: under certain operating conditions, use a syringe to inject a certain concentration of a certain component as a reference standard, test the results, obtain the response value of the component, and draw the response Signal—standard curve of component concentration; use the same method to draw the standard curve of other components;

g. Inject a certain amount of sample to be analyzed under the same conditions, and get the response value of a certain component, then the corresponding concentration can be found from the working curve.

The method of the invention has the advantage that it can qualitatively and quantitatively analyze formaldehyde, methanol and N,N-dimethylhydroxylamine simultaneously in a short time.

The analysis results show that the three peaks of methanol, formaldehyde, N, N-dimethylhydroxylamine are well separated, the peak shape is also good, and the time is relatively short, the analysis can be completed within 10 minutes, so this method can be used for rapid qualitative analysis at the same time Quantitative analysis of methanol, formaldehyde, N,N-dimethylhydroxylamine.

Description of drawings

Fig. 1 is that concentration is the N of 0.3mol/L, after N-dimethylhydroxylamine aqueous solution absorbs 100KGy dose, the chromatogram of liquid phase sample.

Fig. 2 is the graph of the relationship between the formaldehyde concentration and dose produced by the radiolysis of N,N-dimethylhydroxylamine aqueous solution with different concentrations.

Among the figure, the abscissa is the absorbed dose (KGy), and the ordinate is the formaldehyde concentration (mol/L); among the figure, different curves represent the difference between the formaldehyde concentration and the dose produced by the radiolysis of N, N-dimethylhydroxylamine aqueous solution. relation.

Fig. 3 is the graph of the relationship between methanol concentration and dose produced by radiolysis of N, N-dimethylhydroxylamine aqueous solution with different starch degrees.

In the figure, the abscissa is the absorbed dose (KGy), and the ordinate is the methanol concentration (10 ^-4 mol/L); in the figure, different curves represent the concentration of methanol produced by radiolysis of N,N-dimethylhydroxylamine aqueous solution with different concentrations relationship with dose.

Fig. 4 is a diagram showing the relationship between the concentration and dose of N,N-dimethylhydroxylamine in the solution after irradiation.

Among the figure, the abscissa is the absorbed dose (KGy), and the ordinate is N, N-dimethylhydroxylamine concentration (mol/L);

In the figure, different curves represent the relationship between the concentration and the dose of N, N-dimethylhydroxylamine aqueous solution of different concentrations after radiolysis.

Detailed ways

Now with reference to the accompanying drawings, the embodiments of the present invention will be described in detail below.

Example 1

The analysis process and steps in the present embodiment are described as follows:

(1) Prepare a simulated sample and prepare a mixed solution containing formaldehyde, methanol and N, N-dimethylhydroxylamine;

(2) Adopt the gas chromatography of GDX-401 packed column (φ3mm×2m) and the hydrogen flame ionization detector, put the GDX-401 packed column into the chromatograph correctly, pass nitrogen gas, and adjust its flow rate to 20ml/ After 20 minutes, ventilate the air and adjust its flow rate to 300ml/min; set the column temperature to 130°C, set the vaporization chamber temperature to 160°C, and the detector temperature to 160°C; set the gain to 10 ⁹ , and the attenuation to zero. Operating column temperature, vaporization chamber and detector temperature;

(3) When the hydrogen flame ionization detector reaches the set temperature of 160°C, supply hydrogen and adjust the flow of hydrogen to 80ml/min: use an electronic ignition gun to ignite at the outlet of the detector, and then slowly reduce the flow of hydrogen to 20ml /min;

(4) Turn on the power of the N2000 chromatographic data workstation converter, turn on the computer, enter the online workstation, select the detector channel, input the appropriate text and parameters, select "data acquisition", set zero, and take the baseline;

(5) When the baseline is stable, use an airtight medical syringe to extract 1.0 microliter of the prepared mixed solution simulation sample, and quickly inject it into the gas chromatograph, and press the remote control button of the corresponding channel at the same time;

(6) After the sampling analysis is finished, that is, after the peak is finished, press the stop sampling button; then enter the qualitative analysis and quantitative analysis stages, the qualitative analysis adopts the retention time comparison method, and the quantitative analysis adopts the surface method, that is, quantitative sampling—working curve Quantitative sampling - working curve method is: under certain operating conditions, use a syringe to inject a certain concentration of a certain component as a reference standard, test the results, obtain the response value of the component, and draw the response Signal—standard curve of component concentration; use the same method to draw the standard curve of other components;

(7) Inject a certain amount of sample to be analyzed under the same conditions, and obtain the response value of a certain component, then the corresponding concentration can be found from the working curve.

With reference to accompanying drawing, Fig. 1 to Fig. 4 are relevant experimental graphs involved in the method of the present invention.

Claims (1)

1. a formaldehyde, methyl alcohol and N, the analytical approach the during coexistence of N-dimethyl hydroxylamine is characterized in that having following analytic process and step:

A) prepare the simulation sample, preparation contains formaldehyde, methyl alcohol and N, the mixed solution of N-dimethyl hydroxylamine;

B) adopt the GDX-401 packed column of φ 3mm * 2m and the vapor-phase chromatography of flame ionization ditector coupling, the GDX-401 packed column is correctly packed in the chromatograph into logical nitrogen, regulating its flow is 20ml/min, behind the 20min, blowing air, and to regulate its flow be 300ml/min; Setting column temperature is 130 ℃, and setting the vaporizer temperature is 160 ℃, and detector temperature is 160 ℃; Setting gain is 10 ⁹, decay to zero; The temperature of operation vaporizer and detecting device;

C) when flame ionization ditector arrives 160 ℃ of design temperatures, logical hydrogen, adjustings hydrogen flowing quantity is 80ml/min: with the electronics burning torch in the igniting of detecting device exit, put catch fire after, slowly hydrogen flowing quantity is decreased to 20ml/min again;

D) open the power supply of N2000 chromatographic data workstation converter, open computer, enter the station that works online, select detector channel, import appropriate literal and parameter, baseline is returned to zero, walks in selection " data acquisition ";

E) when baseline is steady, extract the above-mentioned ready mixed solution simulation of 1.0 microlitres sample with airtight injector for medical purpose, and inject gas chromatograph fast, press the remote control buttons of respective channel simultaneously;

F) after sampling analysis finishes, after promptly going out the peak and finishing, by stopping the button of sampling; Enter qualitative analysis and quantitative test stage then; The retention time counter point is adopted in qualitative analysis; External standard method, i.e. quantitative sample injection---working curve method is adopted in quantitative test; Quantitative sample injection---working curve method is: under certain operating conditions, inject quantitative certain density certain component with syringe as reference standard, testing result obtains the response of this component, and draws out response signal---the concentration of component typical curve; With the typical curve of drawing out other each component with quadrat method;

G) inject a certain amount of sample to be analyzed under the same conditions, obtain the wherein response of certain component, then from working curve, just can check in its corresponding concentration.

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