A GC detection method for diethyl ethoxymethylenemalonate

Abstract

The invention discloses a GC detection method for diethyl ethoxymethylene malonate. Ethyl malonate, triethyl orthoformate and ethanol are dissolved in acetonitrile to form an impurity reserve solution, diethyl ethoxymethylene malonate is added to the impurity reserve solution, and the solution is dissolved in acetonitrile to prepare a system suitability solution, and the system suitability solution is injected into a gas chromatograph to separate the diethyl ethoxymethylene malonate and its impurities, and detect the content and purity of related substances. The method adopts an Agilent CP Volamine chromatographic column, a FID hydrogen flame detector and a gradient temperature rising program for separation, can quickly separate the diethyl ethoxymethylene malonate and its impurities, has strong specificity, high sensitivity and high accuracy, and is suitable for detecting the content and purity of related substances of the pharmaceutical intermediate diethyl ethoxymethylene malonate.

Description

Technical Field

[0001] The invention belongs to a gas chromatography (GC) method, in particular to a method for determining the content and purity of related substances of diethyl ethoxymethylenemalonate by using GC. Background Art

[0002] Diethyl ethoxymethylenemalonate is an important organic raw material containing multiple active groups in its molecule. It can undergo polycondensation and cyclization condensation with a variety of substances. It is currently mainly used to synthesize norfloxacin and is used as a pharmaceutical and pesticide intermediate. Its molecular formula is C 10 H 16 O 5 , the structural formula is:

[0003] .

[0004] The process impurities in the synthesis process of this compound are difficult to remove. In the directional synthesis of the target compound diethyl ethoxymethylenemalonate, in order to control the content of process impurities, it is necessary to perform quality control on the content and purity of related substances of diethyl ethoxymethylenemalonate.

[0005] So far, no detection method for this compound has been found, and the advantage of this method is that it can be directly applied to a gas chromatography-mass spectrometry detector to quickly conduct impurity research on samples. Summary of the invention

[0006] The object of the present invention is to provide a GC detection method for quickly separating diethyl ethoxymethylene malonate and its impurities, which is used to determine the content and purity of related substances in diethyl ethoxymethylene malonate.

[0007] The technical solution adopted by the present invention to solve the technical problem is: a GC detection method for diethyl ethoxymethylenemalonate, using gas chromatography, Agilent 8860GC equipped with FID hydrogen flame ionization detector, and the GC detection conditions are as follows: chromatographic column: Agilent CP Volamine 30m*0.32mm; injection port temperature: 250°C; detector temperature: 250°C; mobile phase: hydrogen flow rate 30mL / min; air flow rate 400mL / min; nitrogen tail blowing flow rate 25 mL / min; column flow rate 1.8-2.2mL / min; temperature gradient program: initial column temperature is 38-42°C, maintained for 2 min, the temperature is increased to 260°C at a heating rate of 20°C / min, and maintained for 5 min;

[0008] The following steps are involved:

[0009] (1) Take 200 mg each of ethyl malonate, triethyl orthoformate, and ethanol, place them in a volumetric flask, and dissolve them in 20 mL of acetonitrile to prepare the impurity stock solution;

[0010] (2) Take 200 mg of diethyl ethoxymethylenemalonate, add 0.2 mL of impurity stock solution, place in a volumetric flask, and dissolve in 20 mL of acetonitrile to prepare a system suitability solution;

[0011] (3) Take 1 μL of the system suitability solution and inject it into the gas chromatograph to complete the separation of diethyl ethoxymethylenemalonate and its impurities, perform detection and record the chromatogram, and detect the content and purity of related substances.

[0012] Furthermore, the system suitability solution in step (2) contains 10 mg of diethyl ethoxymethylenemalonate per 1 mL of acetonitrile.

[0013] Furthermore, in the step (3), the injection port adopts a split mode with a split ratio of 10:1.

[0014] Furthermore, the chromatographic column is a non-polar capillary column.

[0015] Furthermore, the detector is an Agilent gas chromatograph with a FID detector.

[0016] Furthermore, in the step (3), the purity of diethyl ethoxymethylenemalonate is obtained by area normalization method, and the content of related substances is obtained by external standard method.

[0017] The beneficial effects of the present invention are:

[0018] The present invention adopts an Agilent CP Volamine 30m*0.32mm non-polar capillary chromatographic column, which can effectively separate impurities. The minimum separation degree between known impurities is 22, the specificity is very good, the whole running time of the method is within 25 minutes, and the related substances and contents adopt the same method without any parameter adjustment, and the method has the ability to quickly complete analysis and detection. At the same time, the method can be directly converted into a gas chromatography-mass spectrometry detector for the study of impurities.

[0019] The present invention adopts gas chromatography, which is simpler to operate and has lower analysis cost than liquid phase analysis.

[0020] The invention has high detection sensitivity for known impurities, can accurately quantify 5 μg / mL of impurities, and can accurately detect the content within the range of sample concentration of 5-15 mg / mL, thereby ensuring the accuracy and reliability of the content and purity of related substances of diethyl ethoxymethylenemalonate. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1This is a chromatogram of the Agilent DB 624 30m*0.32mm*1.8μm chromatographic column running in Comparative Example 1 of the present invention;

[0022] Figure 2 This is a chromatogram of the Agilent CP Volamine 30m*0.32mm chromatographic column run in Comparative Example 2 of the present invention;

[0023] Figure 3 The linear graph and data of the nominal concentration of ethanol impurity in Comparative Example 2 of the present invention in the range of 0.05%-0.5%;

[0024] Figure 4 The linear graph and data of the nominal concentration of the impurity triethyl orthoformate in Comparative Example 2 of the present invention in the range of 0.05%-0.5%;

[0025] Figure 5 The linear graph and data of the nominal concentration of ethyl malonate impurity in Comparative Example 2 of the present invention in the range of 0.05%-0.5%;

[0026] Figure 6 The linear graph and data of diethyl ethoxymethylenemalonate in Comparative Example 2 of the present invention and the nominal concentration range of 0.05 to 0.5%;

[0027] Figure 7 The accuracy data of 0.05%, 0.1% and 0.15% of the nominal concentration of diethyl ethoxymethylenemalonate and each impurity sample in Comparative Example 2 of the present invention;

[0028] Figure 8 The linear graph and data of the sample nominal concentration of diethyl ethoxymethylenemalonate in Comparative Example 2 of the present invention in the range of 50% to 150%;

[0029] Fig. 9 This is the system suitability solution chromatogram of the comparative example 2 of the present invention when the column flow rate is adjusted by ±0.2 mL / min;

[0030] Fig.10 This is the system suitability solution chromatogram of Comparative Example 2 of the present invention when the initial column temperature is adjusted by ±2°C. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0032] The applicant found that using an Agilent CP Volamine 30m*0.32mm non-polar capillary column, an injection port temperature of 250°C; a detector temperature of 250°C; a hydrogen flow rate of 30mL / min, an air flow rate of 400mL / min, a nitrogen tail blow flow rate of 25mL / min, and a column flow rate of 1.8-2.2 mL / min; a heating program: an initial column temperature of 38-42°C, maintained for 2min, and the temperature was raised to 260°C at a heating rate of 20°C / min and maintained for 5min, diethyl ethoxymethylenemalonate and its impurities can be effectively separated, thereby accurately determining the content and purity of related substances of diethyl ethoxymethylenemalonate.

[0033] The GC detection method of the present invention can be implemented according to the following method.

[0034] (1) Take 200 mg each of ethyl malonate, triethyl orthoformate, and ethanol, place them in a 20 mL volume, and dissolve them in acetonitrile to prepare the impurity stock solution.

[0035] (2) Take 200 mg of diethyl ethoxymethylenemalonate, add 0.2 mL of impurity stock solution, place in a 20 mL volume, dissolve in acetonitrile, and prepare a system suitability solution.

[0036] (3) Take the system suitability solution of step (2) according to the injection volume of 1 μL, adopt the split mode, and inject it into the gas chromatograph at a split ratio of 10:1 to complete the separation of diethyl ethoxymethylenemalonate and its impurities, and perform detection and record the chromatogram to detect related substances and purity.

[0037] The detection conditions are as follows: chromatographic column: Agilent CP Volamine 30m*0.32mm; chromatographic instrument: Agilent8860GC equipped with FID detector; inlet temperature: 250℃; detector temperature: 250℃; hydrogen flow rate: 30mL / min; air flow rate: 400mL / min; nitrogen tail blow: 25 mL / min; column flow rate: 1.8~2.2 mL / min; injection volume: 1μL; split ratio: 10:1; heating program: initial column temperature is 38~42℃, maintained for 2min, and the temperature is increased to 260℃ at a heating rate of 20℃ / min and maintained for 5min.

[0038] The invention adopts an Agilent CP Volamine chromatographic column and commonly used reagents to realize separation, and the preparation method is simple and easy to operate, so that the efficiency of quality control of diethyl ethoxymethylenemalonate is significantly improved.

[0039] Comparative Example 1

[0040] Chromatographic column: Agilent DB 624 30m*0.32mm*1.8μm capillary column.

[0041] Chromatographic instrument: Agilent 8860GC equipped with FID detector.

[0042] Inlet temperature: 250℃.

[0043] Detector temperature: 250°C.

[0044] Hydrogen flow rate: 30 mL / min; air flow rate: 400 mL / min; nitrogen tail blow: 25 mL / min; column flow rate: 2.0 mL / min.

[0045] Injection volume: 1 μL; split ratio: 10:1.

[0046] Temperature program: the initial column temperature was 40 °C, maintained for 2 min, then the temperature was increased to 260 °C at a heating rate of 20 °C / min and maintained for 5 min.

[0047] Experimental steps:

[0048] (1) Take 200 mg each of ethyl malonate, triethyl orthoformate, and ethanol, place them in a volumetric flask, and dissolve them in 20 mL of acetonitrile to prepare the impurity stock solution.

[0049] (2) Take 200 mg of diethyl ethoxymethylenemalonate, add 0.2 mL of impurity stock solution, place in a volumetric flask, and dissolve in 20 mL of acetonitrile to prepare a system suitability solution.

[0050] (3) Take 1 μL of the system suitability solution and inject it into the gas chromatograph to separate diethyl ethoxymethylenemalonate and its impurities, and detect the content and purity of related substances.

[0051] Record the chromatogram. See the attached Figure 1 In the system suitability solution, the impurities triethyl orthoformate and ethyl malonate co-eluted, and the chromatographic column was not suitable for the detection of related substances of diethyl ethoxymethylenemalonate.

[0052] Comparative Example 2

[0053] Chromatographic column: Agilent CP Volamine 30m*0.32mm.

[0054] Chromatographic instrument: Agilent 8860GC equipped with FID detector.

[0055] Inlet temperature: 250℃.

[0056] Detector temperature: 250°C.

[0057] Hydrogen flow rate: 30 mL / min; air flow rate: 400 mL / min; nitrogen tail blow: 25 mL / min; column flow rate: 1.8-2.2 mL / min.

[0058] Injection volume: 1 μL; split ratio: 10:1.

[0059] Temperature program: the initial column temperature was 38-42°C, maintained for 2 min, then the temperature was increased to 260°C at a rate of 20°C / min and maintained for 5 min.

[0060] Experimental steps:

[0061] (1) Take 200 mg each of ethyl malonate, triethyl orthoformate, and ethanol, place them in a 20 mL volumetric flask, and dissolve them in acetonitrile to prepare impurity stock solution A; take 0.5 mL of the solution and place it in a 50 mL volumetric flask to prepare impurity stock solution B.

[0062] (2) Take 200 mg of diethyl ethoxymethylenemalonate, add 0.2 mL of impurity stock solution A, place in a 20 mL volume, dissolve in acetonitrile, and prepare a system suitability solution.

[0063] (3) Take 200 mg each of diethyl ethoxymethylenemalonate, ethyl malonate, triethyl orthoformate, and ethanol, place them in a 20 mL volumetric flask, dissolve them in acetonitrile, take 0.5 mL of the solution, and place it in a 50 mL volumetric flask as a linear stock solution.

[0064] (4) Take 1 mL of the linear stock solution in step (3) and dilute it to 2 mL to prepare a 0.5% linear solution, labeled as: L-MIX-0.5%.

[0065] (5) Take 1 mL of the linear stock solution in step (3) and dilute it to 5 mL to prepare a 0.2% linear solution, labeled as: L-MIX-0.2%.

[0066] (6) Take 1.5 mL of the linear stock solution in step (3) and dilute it to 10 mL to prepare a 0.15% linear solution, labeled as: L-MIX-0.15%.

[0067] (7) Take 1 mL of the linear stock solution in step (3) and dilute it to 10 mL to prepare a 0.1% linear solution, labeled as: L-MIX-0.1%.

[0068] (8) Take 0.8 mL of the linear stock solution in step (3) and dilute it to 10 mL to prepare a 0.08% linear solution, labeled as: L-MIX-0.08%.

[0069] (9) Take 0.5 mL of the linear stock solution in step (3) and dilute it to 10 mL to prepare a 0.05% linear solution, labeled as: L-MIX-0.05%.

[0070] (10) Take 100 mg of diethyl ethoxymethylenemalonate, place it in a 10 mL container, and dissolve it in acetonitrile to prepare a sample solution.

[0071] (11) In parallel, 100 mg of each diethyl ethoxymethylenemalonate was placed in a 10 mL volumetric impurity tank. 0.5 mL of impurity stock solution B was taken and dissolved in acetonitrile to serve as the spiked solutions, which were labeled as SPK-0.05%-1 and SPK-0.05%-2, respectively.

[0072] (12) In parallel, 100 mg of each diethyl ethoxymethylenemalonate was placed in a 10 mL volumetric impurity tank. 1.0 mL of impurity stock solution B was taken and dissolved in acetonitrile as the spiked solutions, which were labeled as SPK-0.1%-1 and SPK-0.1%-2, respectively.

[0073] (13) In parallel, 100 mg of each diethyl ethoxymethylenemalonate was placed in a 10 mL volumetric impurity tank. 1.5 mL of impurity stock solution B was dissolved in acetonitrile as the spiked solutions, which were labeled as SPK-0.15%-1 and SPK-0.15%-2, respectively.

[0074] (14) About 50 mg, 80 mg, 100 mg, 120 mg, and 150 mg of diethyl ethoxymethylenemalonate were placed in 10 mL volumes, dissolved in acetonitrile, and labeled as sample linear solutions: L-50%, L-80%, L-100%, L-120%, and L-150%.

[0075] (15) Take 1 μL of the above-mentioned system suitability, impurity linear mixed solution (L-MIX solution), sample solution, spiked solution (SPK), and sample linear solution and inject them into the gas chromatograph to record the chromatogram.

[0076] See attached for the results Figure 2 to Figure 5 ,from Figure 2 It can be seen that under this condition, diethyl ethoxymethylenemalonate and its impurity peaks can be completely separated, and the method has good specificity.

[0077] from Figure 3 to Figure 6 It can be seen that ethanol, triethyl orthoformate, ethyl malonate, and diethyl ethoxymethylenemalonate have good linearity within the range of 0.05%-0.5% of the nominal sample concentration.

[0078] from Figure 7It can be seen that the recoveries of ethanol, triethyl orthoformate, and ethyl malonate at nominal sample concentrations of 0.05%, 0.1%, and 0.15% were between 93.3% and 117.3%, with good accuracy.

[0079] from Figure 8 It can be seen that the linearity of diethyl ethoxymethylenemalonate is good within the range of 50%-150% of the nominal concentration of the sample.

[0080] from Fig. 9 It can be seen that by changing the column flow rate by ±0.2 mL / min, diethyl ethoxymethylenemalonate and its impurity peaks can be completely separated.

[0081] from Fig.10 It can be seen that by changing the initial column temperature by ±2°C, diethyl ethoxymethylenemalonate and its impurity peaks can be completely separated.

[0082] The above embodiments are only illustrative of the principles and effects of the present invention, as well as some embodiments of its application. For those skilled in the art, several modifications and improvements may be made without departing from the creative concept of the present invention, and all of these belong to the protection scope of the present invention.

Claims

1. A GC detection method for diethyl ethoxymethylenemalonate, characterized in that: Gas chromatography was used, Agilent 8860GC was equipped with FID hydrogen flame ionization detector, and the GC detection conditions were as follows Chromatographic column: Agilent CP Volamine 30m*0.32mm; Inlet temperature: 250°C; Detector temperature: 250°C; Mobile phase: hydrogen flow rate 30 mL / min; air flow rate 400 mL / min; nitrogen tail gas flow rate 25 mL / min; column flow rate 1.8-2.2 mL / min; Temperature gradient program: initial column temperature was 38-42 °C, maintained for 2 min, then the temperature was increased to 260 °C at a rate of 20 °C / min and maintained for 5 min; The following steps are involved: (1) Take 200 mg each of ethyl malonate, triethyl orthoformate, and ethanol, and dissolve them in 20 mL of acetonitrile to prepare the impurity stock solution; (2) Take 200 mg of diethyl ethoxymethylenemalonate, add 0.2 mL of impurity stock solution, dissolve in 20 mL of acetonitrile to prepare a system suitability solution; (3) Take 1 μL of the system suitability solution and inject it into the gas chromatograph to complete the separation of diethyl ethoxymethylenemalonate and its impurities, record the chromatogram, and detect the content and purity of related substances.

2. The GC detection method of diethyl ethoxymethylenemalonate according to claim 1, wherein In the step (3), the injection port adopts a split mode with a split ratio of 10:

1.

3. The GC detection method of a kind of diethyl ethoxymethylenemalonate according to claim 1 or 2, characterized in that, In the step (3), the purity of diethyl ethoxymethylenemalonate is obtained by area normalization method, and the content of related substances is obtained by external standard method.

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