CN113848276A - Method for determining residual solvent in synthetic drug based on pre-column separation - Google Patents
Method for determining residual solvent in synthetic drug based on pre-column separation Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N2030/062—Preparation extracting sample from raw material
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- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
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Abstract
The invention relates to a method for measuring residual solvent in a synthetic drug based on pre-column separation, which sequentially comprises the following four steps: step one, preparing a sample solution: dissolving toremifene citrate raw material medicine by using an organic solvent, wherein the residual solvent to be detected is acetone, tetrahydrofuran, ethyl acetate and toluene; extracting a sample solution by adopting a hollow fiber membrane liquid-liquid two-phase liquid-phase microextraction technology, wherein an extracting agent is n-hexane-3-methylimidazole hexafluorophosphate room-temperature ionic liquid; step three, adopting a separator to perform pre-column separation of the extractant: the separator is internally provided with filter cotton for adsorbing the room-temperature ionic liquid extractant and separating the front part of the column of the room-temperature ionic liquid extractant so as to prevent the room-temperature ionic liquid from damaging the chromatographic column; step four, residual solvent GC analysis: the residual solvent in the extraction concentrated solution is driven by the carrier gas, flows through the GC sample inlet, flows into the GC instrument for chromatographic analysis, and has low detection limit, good accuracy and high precision when being used for determining the residual solvent in the synthetic drugs in the organic non-aqueous system.
Description
Technical Field
The invention relates to the technical field of detection and analysis, in particular to a novel method for determining residual solvent in synthetic drugs, and specifically relates to a method for determining residual solvent in synthetic drugs in a non-aqueous system based on an LPME-GC (liquid microextraction-gas chromatography) method for separation before a room-temperature ionic liquid column.
Background
In order to improve the yield and purity of the medicine, an organic solvent is required to be used in the medicine synthesis process, but the residual quantity of the organic solvent is harmful to human health when exceeding a safe value. In order to protect patients from being damaged by residual organic solvents in medicines and ensure the quality of medicines, the registration technology of human medicines requires Q3C impurity which is passed by international coordination: guidance for residual solvent "proposes to use chromatographic techniques to determine residual solvent and requires the use of uniform methods of determination as defined in pharmacopoeia to the greatest extent possible. The methods of HS-GC (static headspace gas chromatography) are prescribed or recommended in the Chinese pharmacopoeia, the United states pharmacopoeia and the European pharmacopoeia. However, the HS-GC method requires an expensive automatic headspace sampling device, and the measurement cost is high.
The LPME-GC (liquid phase microextraction gas chromatography) method adopts LPME (liquid phase microextraction) technology to extract and concentrate liquid samples, and injects the extracted and concentrated liquid into a GC (gas chromatography) instrument in a manual sample injection mode to analyze residual solvent in the liquid samples. The LPME-GC method has the advantages of simple device, small using amount of organic solvent, simple and convenient operation, short determination time, good selectivity, high precision, low detection limit and good reproducibility.
The LPME technology is mainly used as a sample pretreatment means, and comprises two extraction modes, namely micro-drop liquid phase micro-extraction and hollow fiber membrane liquid phase micro-extraction, wherein the latter extraction mode is further divided into an HF-LPME (hollow fiber membrane liquid-liquid two-phase micro-extraction) mode and an HF-LLLME (hollow fiber membrane liquid-liquid three-phase micro-extraction) mode. Micro-droplet phase micro-extraction exposes a single droplet of the extractant to the sample solution, which migrates the target compound from solution to the extractant, achieving concentration. The hollow fiber membrane liquid-phase microextraction operation is characterized by that firstly, a certain quantity of extractant is injected into the cavity of hollow fiber tube, then the hollow fiber tube is placed in sample solution, and the target compound is transferred into extraction phase by means of organic liquid membrane of hollow fiber pore so as to implement concentration of trace organic matter. The hollow fiber membrane is characterized in that the inner cavity and the pore wall of the hollow fiber membrane are the same organic extractant, which is called HF-LPME method, and the hollow fiber membrane is not the same organic extractant, which is called HF-LLLME method. It can be seen that: the LPME technology integrates sampling, extraction and concentration. When the LPME technology is used for sample pretreatment, a sample solution needs to be stirred in order to obtain a good extraction effect, and the micro-drop liquid phase micro-extraction technology can only treat a relatively clean liquid sample because the droplets of the extractant drop off in the stirring process, so that the application range of the LPME technology is relatively narrow. The special structure of the commercial hollow fiber tube can selectively allow target compounds to pass through and prevent large-particle impurities and macromolecular compounds from entering, so that the hollow fiber membrane can process complex sample solution; the extracting agent is arranged in the hollow fiber tube, so that the stirring speed can be increased, the extraction time can be shortened, and the extraction and the concentration can be quickly and efficiently carried out. Therefore, the method comprises the following steps: the invention adopts a hollow fiber membrane liquid-phase micro-extraction mode to extract residual solvent in the synthesized medicaments.
The LPME-GC method for determining volatile organic compounds needs three steps of sample pretreatment, manual sample introduction and GC analysis, and the flow is shown in figure 1.
As can be seen from fig. 1: after the sample solution is extracted and concentrated by the LPME-GC method, an extracting agent in the concentrated solution and a target compound are injected into a GC sample inlet in a manual sample injection mode and are carried into a GC instrument by carrier gas for analysis. Thus, the LPME-GC method requires that the extractant simultaneously satisfy two conditions: has good enriching effect on target compounds and cannot damage chromatographic columns.
Compared with the traditional organic extractant, the room-temperature ionic liquid has larger suspended drop volume and longer extraction time, so that the enrichment factor is obviously increased, the sensitivity and the reliability of the method are improved, favorable conditions are provided for using the room-temperature ionic liquid as the extractant for liquid-phase microextraction, and the room-temperature ionic liquid replaces the traditional organic extractant, thereby being the focus of research on the liquid-phase microextraction technology in the analysis field. However, room temperature ionic liquids have destructive effects on the chromatography column, resulting in limited use as extractants for LPME-GC methods.
At present, the research on the LPME-GC method at home and abroad mainly focuses on measuring trace volatile substances in a water phase, and the system research for measuring the trace volatile organic compounds in an organic non-water system is lacked. Through literature retrieval, the room temperature ionic liquid used as an extracting agent of the LPME-GC method has few varieties, especially lacks the systematic research of the application of the room temperature ionic liquid in the LPME-GC method in a non-aqueous system, and the application range of the room temperature ionic liquid LPME-GC method needs to be expanded.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for measuring residual solvent in synthetic drugs based on pre-column separation, which adopts a liquid-phase microextraction-gas chromatography technology to measure the residual solvent in the synthetic drugs in an organic non-aqueous system, can perform pre-column separation on a room-temperature ionic liquid extractant so as to avoid the room-temperature ionic liquid from damaging a chromatographic column, and has the advantages of low detection limit of the residual solvent in the drugs, good accuracy and high precision.
The technical scheme adopted by the invention for solving the technical problems is as follows: a method for measuring residual solvent in a synthetic drug based on pre-column separation is characterized by sequentially comprising the following four steps:
step one, preparing a sample solution:
the synthetic drug is toremifene citrate, the drug is dissolved by adopting an organic solvent medium, and the residual solvent to be detected is acetone, tetrahydrofuran, ethyl acetate and toluene;
step two, LPME extraction, and preparation of concentrated solution:
the LPME technology is a hollow fiber membrane liquid-liquid two-phase liquid-phase microextraction (HF-LPME) method, and the hollow fiber tube is a polypropylene hollow fiber tube; the extractant is n-hexane-3-methylimidazole hexafluorophosphate room-temperature ionic liquid; extracting residual solvent in the sample solution under the conditions of heating and stirring to prepare an extraction concentrated solution;
step three, separating the extractant before column:
separating the extractant by a separator before column, wherein the separator is arranged at the front end of a sample inlet of a GC instrument, extracting concentrated solution is injected into the separator, and the extractant is intercepted by filter cotton arranged in the separator and does not enter a chromatographic column, so that the extractant is separated before column; the carrier gas drives the residual solvent to be detected in the extraction concentrated solution to flow through the GC sample inlet and enter the GC instrument;
step four, residual solvent GC analysis:
the residual solvent to be detected in the extraction concentrated solution is driven by carrier gas, flows through a sample inlet of a GC instrument, flows into a GC chromatographic column for separation and detection by a detector, and GC analysis is realized according to the result; the chromatographic column in the GC instrument is a capillary gas chromatographic column.
As an improvement, the used GC instrument is reconstructed, and a gas path three-way regulating valve is additionally arranged in a gas path system of the GC instrument, so that the GC instrument can be freely switched between two states of separation before an extractant column is separated by using a separator and sample injection detection by directly using the GC instrument.
Further, the gas circuit three-way regulating valve is installed between a sample inlet of the GC instrument and the electronic flowmeter, one end of the gas circuit three-way regulating valve is connected with a connector of the separator through a gas carrying pipe, the other end of the gas circuit three-way regulating valve is connected with the sample inlet of the GC instrument, the third end of the gas circuit three-way regulating valve is connected with the GC electronic flowmeter, and carrier gas flows through the purifier and the GC electronic flowmeter from a carrier gas steel bottle and flows into the gas circuit three-way regulating valve. The reconstruction of the gas path system of the gas chromatograph is shown in figure 2.
The separator is arranged at the front end of the GC sample inlet, and is integrated with the GC instrument through a gas circuit three-way regulating valve, and the carrier gas pressure of the separator is directly controlled by a GC instrument chemical workstation. The installation of the separator of the invention is schematically illustrated in figure 3.
The filter cotton is quartz cotton with the diameter of 1-3 mu m special for the element analyzer and is replaceable. More preferably, the filter cotton is disposable in order to avoid extractant residue, reduce reagent error and improve method precision.
Further, the separator includes from last to the spiral shell lid, three way connection and the base of assembling in proper order down, forms a little air chamber in three way connection after spiral shell lid, three way connection, the base assembly, wherein three way connection's one side is seted up the inlet port that is linked together with little air chamber, inlet port department is equipped with and links to each other through carrier gas pipe and gas circuit tee bend governing valve, is used for letting in the joint of carrier gas, the lower extreme central point of base puts and vertically sets up the aperture that is linked together with little air chamber, aperture department integral type is fixed with the tip syringe needle of stainless steel, the filter pulp locate in the base, the top of tip syringe needle.
Furthermore, in order to facilitate the connection and the disassembly of the base and the three-way joint, a stepped slotted hole for inserting and connecting the lower end of the three-way joint is concavely arranged in the middle of the upper end of the base and is divided into three sections with the upper part wide and the lower part narrow, wherein an internal thread is arranged on the inner wall of the upper section of the stepped slotted hole, a through inner hole is axially arranged in the middle of the three-way joint, a reducing section matched and connected with the stepped slotted hole is arranged at the lower end of the three-way joint and is divided into an upper section and a lower section, the upper section is an external thread section matched and connected with the internal thread of the stepped slotted hole, the lower section is a cylindrical section corresponding to the middle section of the stepped slotted hole, and the lower end of the three-way joint is inserted in the base and is fixedly connected with the base through threads.
Further, the filter cotton is quartz cotton with the diameter of 1-3 microns special for the element analyzer, and is arranged in a groove at the lower section of a stepped slot hole of the base and above a small hole of the base; an O-shaped sealing ring made of polytetrafluoroethylene is lined between the top of the external thread section of the three-way joint and the inner wall of the base, so that good air tightness between the three-way joint and the base is ensured.
Furthermore, a center hole which is penetrated through and can be inserted by a microsyringe is axially formed in the center of the screw cap, a reducing external thread connecting column is formed at the lower end of the screw cap, an internal thread connecting groove corresponding to the external thread connecting column of the screw cap is concavely formed in the middle of the upper end face of the three-way joint, a groove is formed between the lower end of the internal thread connecting groove of the three-way joint and the inner hole, a sample injection sealing gasket is arranged in the groove, and the screw cap is screwed up and fixed with the upper end of the three-way joint in a threaded connection mode and is abutted to and sealed with the upper end of the sample injection sealing gasket.
Furthermore, the air inlet is radially arranged on one side of the middle of the three-way joint along the three-way joint, the air inlet is communicated with an inner hole of the three-way joint, the joint is a double-clamping sleeve rotating outer cone threaded joint made of brass H62, and the joint is arranged at the air inlet in a threaded connection mode.
Further, in the step one, the organic solvent is at least one of methanol, dimethyl sulfoxide, N-dimethylformamide and N, N-dimethylacetamide.
Further designing, in the second step, the hollow fiber tube in the liquid phase micro-extraction device is a polypropylene hollow fiber tube with the wall thickness of 180-220 μm, the aperture of 0.19-0.21 μm and the inner diameter of 550-650 μm; the extraction conditions include an extraction heating temperature of 26.5-29.5 ℃, an extraction heating time of 5-10 min, and a stirring speed of 800-1000 rpm. More preferably, the extraction conditions are that the extraction heating temperature is 28 ℃, the extraction heating time is 8min, and the stirring speed is 1000 r/min.
And in the fourth step, the chromatographic column used by the gas chromatograph is a capillary gas chromatographic column.
Compared with the prior art, the invention has the advantages that:
firstly, the room temperature ionic liquid extractant is separated in front of a column through a separator, so that the room temperature ionic liquid is prevented from damaging a chromatographic column, the room temperature ionic liquid extractant which has good extraction effect on trace volatile organic compounds but can damage the chromatographic column can be used for an LPME-GC method, and the extractant selection range of the LPME-GC method is expanded;
secondly, the extraction agent pre-column separation technology is combined with the LPME extraction technology and the GC analysis, an extraction agent pre-column separation LPME-GC method is initiated, the flow of LPME extraction → extraction agent pre-column separation → GC analysis is adopted, the trace volatile organic compound is firstly determined in the organic non-aqueous system by the LPME-GC method, the blank of the LPME-GC method for determining the trace volatile organic compound in the non-aqueous system is filled, a solid foundation is laid for expanding the application range of the LPME-GC method, and a new chapter is opened;
research results of LPME-GC method for separating normal hexane-3-methylimidazole hexafluorophosphate at room temperature by ion liquid column front separation in non-aqueous system to determine residual solvents of acetone, tetrahydrofuran, ethyl acetate and toluene show that: the separation degree of the 4 residual solvents and the solvent medium dimethyl sulfoxide accords with the regulations of Chinese pharmacopoeia, American pharmacopoeia and European pharmacopoeia, the enrichment multiple is far higher than that of a common organic extracting agent, the detection limit of the method is lower than that of an HS-GC (static headspace gas chromatography) method, the sensitivity is higher than that of the HS-GC method, the linearity is good, the precision is high, the method is superior to the HS-GC method, the residual solvents can be determined by replacing the HS-GC method, the high cost required for purchasing a headspace instrument is avoided, the economic value of popularization is high, and the method for detecting trace volatile organic matters by separating the LPME-GC method before the room-temperature ionic liquid column is also verified to be effective and feasible.
Drawings
FIG. 1 is a flow chart of a LPME-GC process before modification;
FIG. 2 is a schematic diagram of a reconstruction of a gas path system of a gas chromatograph;
FIG. 3 is a schematic view of the installation of the separator of the present invention;
FIG. 4 is a schematic diagram of the operation of the extraction apparatus of the present invention;
FIG. 5 is a flow diagram of a pre-column separation LPME-GC method of the present invention;
FIG. 6 is a schematic diagram of the separator;
FIG. 7 is a cross-sectional view taken along line A-A of FIG. 6;
FIG. 8 is a schematic view of the structure of the base of the separator;
FIG. 9 is a schematic view of the construction of a tee joint for the separator;
FIG. 10 is a cross-sectional view of FIG. 9;
FIG. 11 is a schematic structural view of the screw cap;
FIG. 12 is a chromatogram of residual solvent in a standard solution;
fig. 13 is a chromatogram of residual solvent in a sample solution.
Detailed Description
The following examples further describe the present invention in detail.
The experimental apparatus related in this embodiment mainly includes: gas chromatograph: model SHIMADZU GC2010, equipped with a hydrogen Flame Ionization Detector (FID), SHIMADZU corporation, japan; water purification machine: Milli-Q gas model, Millipore, USA, resistivity 18.2M Ω cm (25 deg.C); a refrigerator: BC-50ES model, Haier electric appliances, Inc. of China; electronic analytical balance: BSA224S model, sartorius scientific instruments (beijing) ltd; an ultrasonic cleaning machine: SB-80, Ningbo Xinzhi Biotech Co., Ltd; an extractant separator, self-made.
The experimental reagent related in the embodiment mainly comprises: acetone: gas chromatography purity (content 99.65%), national drug group chemical reagent limited; tetrahydrofuran: gas chromatography purity (content 99.9794%), national drug group chemical reagents ltd; ethyl acetate: gas chromatography purity (content 99.86%), national drug group chemical reagent limited; toluene: gas chromatography purity (content 99.52%), national drug group chemical reagent limited; dimethyl sulfoxide: chromatographic purity (content is more than or equal to 99.9%), Shanghai Aladdin reagent GmbH; extracting agent: the normal hexane-3-methylimidazole hexafluorophosphate room-temperature ionic liquid is prepared by self.
The method for determining the residual solvent in the synthetic drug based on pre-column separation in the embodiment sequentially comprises the following four steps:
step one, preparing a sample solution:
the synthetic drug is toremifene citrate, and is soluble in water, methanol, dimethyl sulfoxide, N-dimethylformamide and N, N-dimethylacetamide; the organic solvent medium used for dissolving the toremifene citrate bulk drug is at least one of methanol, dimethyl sulfoxide, N-dimethylformamide and N, N-dimethylacetamide and is used for preparing a sample solution; and (3) determining residual solvents in the bulk drugs in an organic non-aqueous system, wherein the residual solvents to be determined are acetone, tetrahydrofuran, ethyl acetate and toluene.
Step two, LPME extraction, and preparation of concentrated solution:
the LPME technology is HF-LPME (hollow fiber membrane liquid-liquid two-phase liquid-phase microextraction), and the hollow fiber tube is a polypropylene hollow fiber tube with the wall thickness of 180-220 mu m, the aperture of 0.19-0.21 mu m and the inner diameter of 550-650 mu m; the extractant is n-hexane-3-methylimidazole hexafluorophosphate room-temperature ionic liquid; the extraction heating temperature is 26.5-29.5 ℃, the extraction heating time is 5-10 min, and the stirring speed is 800-1000 r/min.
The operation of the LPME extraction apparatus of the present invention is schematically shown in FIG. 4.
Step three, separating the extractant before column:
the separator is filled with extraction concentrated solution, and an extractant in the extraction concentrated solution is adsorbed by filter cotton arranged in the separator, is trapped in the separator and cannot enter a chromatographic column, so that the separation before the extractant column is realized; the residual solvent to be detected in the extraction concentrated solution is driven by the carrier gas, flows through the sample inlet of the GC instrument and flows into the chromatographic column.
The separator is installed at the front end of a sample inlet of the GC instrument and integrated with the GC instrument through a gas circuit three-way regulating valve, and the front separation operation of the extractant column is accurately controlled and accurately finely adjusted through a chemical workstation of the GC instrument. In order to prevent extractant residue in the separator, the filter cotton arranged in the separator is disposable and replaceable.
Step four, residual solvent GC analysis:
the carrier gas flows into the separator and fills the small gas chamber according to the working conditions set by the chemical workstation of the GC instrument, and drives the residual solvent to be detected in the extraction concentrated solution to flow through the sample inlet of the GC instrument and flow into the chromatographic column of the GC instrument for chromatographic analysis. In order to obtain good separation, the GC apparatus uses a capillary gas chromatography column.
In a word, the extraction agent pre-column separation is combined with the LPME extraction technology and the GC analysis, and the trace residual solvents of acetone, tetrahydrofuran, ethyl acetate and toluene in the toremifene citrate bulk drug are determined in an organic non-aqueous system by adopting a flow of LPME extraction → extraction agent pre-column separation → GC analysis and a pre-column separation LPME-GC (liquid phase microextraction-gas chromatography) method.
The flow chart of the LPME-GC method for pre-column separation in this example for the determination of the residual solvent in the drug is shown in FIG. 5.
The following is a detailed description of the specific contents of the above four steps:
step one, preparing a sample solution:
(1) selection of the solvent medium:
the toremifene citrate is soluble in methanol, dimethyl sulfoxide, N-dimethylformamide and N, N-dimethylacetamide, and the dimethyl sulfoxide is selected as an organic solvent medium because the boiling point of the dimethyl sulfoxide is higher than that of the methanol, the N, N-dimethylformamide and the N, N-dimethylacetamide, and 4 solvents to be detected, such as acetone, tetrahydrofuran, ethyl acetate and toluene, are not interfered during chromatographic analysis, and the separation effect is good.
(2) Solution preparation:
stock solution: 6.318g of acetone, 4.443g of tetrahydrofuran, 8.104g of ethyl acetate and 8.659g of toluene are accurately weighed in a 100mL volumetric flask, diluted by dimethyl sulfoxide, metered to a scale and shaken uniformly to obtain 63.18mg/mL of acetone, 44.43mg/mL of tetrahydrofuran, 81.04mg/mL of ethyl acetate and 86.59mg/mL of toluene standard stock solutions. Diluting with dimethyl sulfoxide according to actual needs to obtain a standard solution.
Sample solution: accurately weighing 0.1000 +/-0.0010 g of toremifene citrate in a 20mL headspace bottle for determining the content of acetone, and accurately weighing 1.7500 +/-0.0010 g of toremifene citrate of the same batch number in the 20mL headspace bottle for determining the content of tetrahydrofuran, ethyl acetate and toluene; adding 10.00mL of dimethyl sulfoxide respectively, covering, sealing, and vibrating to completely dissolve the toremifene citrate.
Each of the above solutions was stored at 4 ℃ until use.
Step two, LPME extraction, preparation of concentrated solution:
(1) selection of the room-temperature ionic liquid of the extractant:
because acetone, tetrahydrofuran, ethyl acetate and toluene are polar organic matters, the enrichment times of the polar organic matters can be increased by adopting a polar extracting agent according to the principle of 'similarity and compatibility'. The normal hexane-3-methylimidazole hexafluorophosphate room-temperature ionic liquid with high polarity is selected as an extracting agent, the enrichment times of 4 residual solvents of acetone, tetrahydrofuran, ethyl acetate and toluene are far higher than those of a common organic extracting agent, the enrichment effect is good, and therefore: the n-hexane-3-methylimidazolium hexafluorophosphate room temperature ionic liquid is selected as the extracting agent.
(2) Determining the LPME mode:
the residual solvent to be detected in the solution is extracted under the conditions of heating and stirring, an Accurel Q3/2 polypropylene hollow fiber tube produced by German Membrana company is used as an LPME material, the wall thickness of the hollow fiber tube is 180-220 mu m, the aperture is 0.19-0.21 mu m, and the inner diameter is 550-650 mu m. The special structure can selectively allow target compounds to pass through, can prevent large-particle impurities and macromolecular compounds from entering, and can treat complex sample solution. The normal hexane-3-methylimidazole hexafluorophosphate room temperature ionic liquid extractant is injected into the hollow fiber tube, and the inner cavity and the hole wall of the hollow fiber membrane are both provided with the extractant, so that: the extraction mode is HF-LPME (hollow fiber membrane liquid-liquid two-phase liquid-phase microextraction) mode.
(3) Operation of Liquid Phase Micro Extraction (LPME) unit:
as shown in fig. 4, the hollow fiber liquid phase micro-extraction device comprises an extraction container and a low-temperature constant-temperature reaction bath, the extraction container comprises a headspace bottle 41 and a bottle cap 40, a standard solution or a sample solution 42, a magnetic stirrer 43 and a polypropylene hollow fiber tube 44 are arranged in the headspace bottle 41, an extractant is precisely measured by an airtight microsyringe 45, a concentrated solution obtained by extraction is extracted by a microsyringe 46, and the airtight microsyringe 45 and the microsyringe 46 respectively penetrate through a silica gel pad 47 in the bottle cap 40 and are connected through the polypropylene hollow fiber tube 44 with a certain length arranged in the headspace bottle.
During extraction, the bottle cap 40 is screwed down, the headspace bottle 41 is placed in a low-temperature constant-temperature reaction bath, and the extractant in the airtight microsyringe 45 is completely injected into the polypropylene hollow fiber tube 44, and extraction is performed under heating and stirring conditions. The extraction operation is schematically shown in FIG. 4.
(4) Optimizing LPME conditions:
the method comprises the following steps of taking room-temperature ionic liquid n-hexane-3-methylimidazole hexafluorophosphate as an extracting agent, and carrying out LPME condition research on acetone, tetrahydrofuran, ethyl acetate and toluene to be tested in an HF-LPME mode on extraction heating temperature, extraction heating time and stirring speed:
optimization of extraction heating temperature:
under the conditions that the extraction heating time is 8min and the stirring speed is 1000 r/min, 4 residual solvents in the standard solution can not completely generate peaks under the condition that the extraction heating temperature is lower than 26 ℃, and n-hexane-3-methylimidazole hexafluorophosphate can be decomposed when the extraction heating temperature is higher than 30 ℃, so that: the chromatographic peak areas of the 4 residual solvents were compared at extraction heating temperatures of 26.5 ℃, 27 ℃, 27.5 ℃, 28 ℃, 28.5 ℃, 29 ℃ and 29.5 ℃: with the rise of the extraction heating temperature, the chromatographic peak areas of the 4 residual solvents are gradually increased, the temperature reaches the maximum at 28 ℃, and at the moment, the peak areas of acetone, tetrahydrofuran, ethyl acetate and toluene are the maximum, and the detection sensitivity is higher, so that: the preferred temperature of 28 ℃ is the extraction heating temperature.
Extraction heating time optimization:
under the conditions that the extraction heating temperature is 28 ℃ and the stirring speed is 1000 r/min, 4 residual solvents in the standard solution are measured when the extraction heating time is 5min, 6min, 7min, 8min, 8.5min, 9min and 10min, and the following results are found: with the extension of the extraction heating time, the chromatographic peak areas of acetone, tetrahydrofuran, ethyl acetate and toluene are gradually increased, the peak areas are almost constant when the time is 8-8.5 min, and the peak areas begin to decrease when the time is 9min, so that: the extraction heating time is preferably 8 min.
Thirdly, optimizing the stirring speed:
under the conditions that the extraction heating temperature is 28 ℃ and the extraction heating time is 8min, chromatographic peak areas of 4 residual solvents in the standard solution are respectively measured at stirring speeds of 800 revolutions/min, 900 revolutions/min, 1000 revolutions/min, 1050 revolutions/min and 1100 revolutions/min, and the following results are found: with the acceleration of the stirring speed, the chromatographic peak areas of acetone, tetrahydrofuran, ethyl acetate and toluene are increased and then decreased, and the chromatographic peak areas of the acetone, the tetrahydrofuran, the ethyl acetate and the toluene are the largest when the stirring speed is 1000 r/min, so that: the stirring rate is preferably 1000 revolutions per minute.
In summary, the normal hexane-3-methylimidazolium hexafluorophosphate room temperature ionic liquid is selected as the extractant, the concentrated solution is prepared by adopting the HF-LPME mode and extracting under the conditions of the extraction heating temperature of 28 ℃, the extraction heating time of 8min and the stirring speed of 1000 r/min, and the extracted concentrated solution extracted by the microsyringe 46 is injected into a separator for pre-column separation of the extractant.
Step three, separating the extractant before column:
(1) the separation mode of the extracting agent is as follows:
the adoption of the pre-column mode can not efficiently and repeatedly adsorb and extract the extractant in the concentrated solution, and can not ensure that 4 residual solvents in the concentrated solution are not adsorbed, so that: the extraction agent n-hexane-3-methylimidazole hexafluorophosphate room temperature ionic liquid in the extraction concentrated solution cannot be separated in a pre-column mode, and a separator is adopted for pre-column separation.
The extraction concentrated solution is injected into a separator, filter cotton arranged in the separator can adsorb an extractant n-hexane-3-methylimidazole hexafluorophosphate room-temperature ionic liquid in the extraction concentrated solution, the extractant n-hexane-3-methylimidazole hexafluorophosphate room-temperature ionic liquid is retained in the separator and prevented from entering a chromatographic column, and acetone, tetrahydrofuran, ethyl acetate and toluene in the extraction concentrated solution are not adsorbed by the filter cotton and can be completely carried into the chromatographic column by carrier gas, so that: the n-hexane-3-methylimidazolium hexafluorophosphate can be subjected to pre-column separation by using a separator.
The filter cotton is the dedicated 1 ~ 3 mu m quartz cotton of element analysis appearance, in order to avoid having the extractant residue in the separator, the quartz cotton disposable, removable. The method adopts a separator for pre-column separation of the extractant, and not only needs the separator to be arranged at the front end of a sample inlet of the GC instrument (shown in figure 3), but also needs to reconstruct a gas circuit system of the GC instrument.
(2) Modifying a gas path system of the GC instrument:
and (4) modifying the gas path system of the used Shimadzu GC2010 GC instrument. As shown in fig. 2, the GC instrument gas circuit system modification method includes: and a gas path three-way regulating valve is arranged between the sample inlet of the GC instrument and the electronic flowmeter, one end of the gas path three-way regulating valve is connected with the joint 4 of the separator through a gas carrying pipe, the other end of the gas path three-way regulating valve is connected with the sample inlet of the GC instrument, and the third end of the gas path three-way regulating valve is connected with the GC electronic flowmeter. The carrier gas flowing out of the carrier gas steel cylinder flows through the purifier and the GC electronic flowmeter and then flows into the gas path three-way regulating valve.
The gas circuit three-way valve is arranged, so that the separator and the GC instrument are integrated, the operation of the separator can be accurately controlled and finely adjusted by directly using a chemical workstation in the GC instrument, and the precision of the method is improved; through the gas circuit three-way regulating valve, the whole experimental device can be freely switched between two states of directly using a GC instrument for sample injection detection and using a separator for extraction agent column separation.
(3) Structure of the separator:
the separator has the following structure:
as shown in fig. 6 to 11, the separator 200 includes a screw cap 1, a three-way joint 2 and a base 3 which are assembled in sequence from top to bottom, a small air chamber a is formed in the three-way joint 2 after the screw cap 1, the three-way joint 2 and the base 3 are assembled, wherein an air inlet 23 is formed in one side of the three-way joint 2 and communicated with the small air chamber a, a joint 4 is arranged at the air inlet 23, the joint 4 is directly connected with an air path three-way regulating valve through an air carrying pipe, a small hole 32 communicated with the small air chamber a is longitudinally formed in the center of the lower end of the base 3, a tip needle 5 made of stainless steel is fixed at the small hole 32, the tip needle 5 can be directly inserted into a sample inlet of a GC instrument, and disposable and replaceable filter cotton 7 for preventing an extractant from entering a chromatographic column is arranged in the base 3 and above the tip needle 5.
The specific assembly structure is as follows: the middle part of the upper end of the base 3 is concavely provided with a stepped slotted hole 31 for inserting and connecting the lower end of the three-way joint 2, the stepped slotted hole 31 is divided into three sections with wide upper part and narrow lower part, wherein the inner wall of the upper section of the stepped slotted hole 31 is provided with internal threads. The middle part of the three-way joint 2 is axially provided with a through inner hole 21, the lower end of the three-way joint 2 is provided with a reducing section 22 which is matched and connected with the stepped slotted hole 31, the reducing section 22 is divided into an upper section and a lower section, wherein the upper section is an external thread section which is matched and connected with the internal thread of the stepped slotted hole 31, the lower section is a cylindrical section which corresponds to the middle section of the stepped slotted hole 31, and the lower end of the three-way joint 2 is inserted in the base 3 and is fixedly connected with the base 3 through threads. The center position of the screw cap 1 is axially provided with a through center hole 11 for inserting the microsyringe 46, the lower end of the screw cap 1 is formed with a reducing external thread connecting column, the middle part of the upper end surface of the three-way joint 2 is concavely provided with an internal thread connecting groove 24 corresponding to the external thread connecting column of the screw cap 1, a groove 25 is arranged between the lower end of the internal thread connecting groove 24 of the three-way joint 2 and an inner hole, a sample injection sealing gasket 6 is arranged in the groove 25, and the screw cap 1 is screwed up and fixed with the upper end of the three-way joint 2 in a thread connection mode and is abutted and sealed with the upper end of the sample injection sealing gasket 6.
The filter cotton 7 is quartz cotton with the diameter of 1-3 mu m special for the element analyzer, and the filter cotton 7 is arranged in a groove at the lower section of a stepped slot hole 31 of the base 3 and is positioned above a small hole 32 of the base 3. An O-shaped sealing ring 8 made of polytetrafluoroethylene is lined between the top of the thread section on the outer side of the reducing section 22 of the three-way joint 2 and the inner wall of the stepped slotted hole 31 of the base 3. The air inlet hole 23 is arranged at one side of the middle part of the three-way joint 2, and the air inlet hole 23 is communicated with the inner hole 21 of the three-way joint 2; the connector 4 is a double-clamping sleeve external cone threaded connector made of brass H62, and the connector 4 is installed at the air inlet hole 23 in a threaded connection mode. One end of the gas path three-way regulating valve is connected with the joint 4 of the separator through a gas carrying pipe, the other end is connected with a sample inlet of the GC instrument, and the third end is connected with an electronic flowmeter of the GC instrument, which is shown in detail in figure 2.
The outer surfaces of the screw cap 1, the three-way joint 2 and the base 3 of the embodiment are all in an outer hexagon shape, and after the screw cap 1, the three-way joint 2 and the base 3 are assembled, the outer surfaces are flush; a sample introduction sealing gasket 6 is arranged above the groove 25 of the three-way joint 2, and the screw cap 1 can be screwed tightly with the sample introduction sealing gasket to prevent carrier gas and volatile components from overflowing upwards; an O-shaped sealing ring 8 is arranged at the top of the threaded opening at the outer side of the reducing section 22 of the three-way joint 2 so as to ensure the air tightness between the three-way joint 2 and the base 3. The lower end of the base 3 is provided with a reducing cylindrical section, the upper end of the pointed needle 5 is inserted in the small hole 32, and the lower end extends out of the base 3. The pointed needle 5 is a special microsyringe needle of a gas chromatograph, the outer diameter of the needle is 2mm, the length of the needle is 6cm,
the working principle of the separator is as follows:
the separator 200 in this embodiment is installed at the front end of the sample inlet of the GC instrument, the carrier gas flows into the separator after flowing through the gas path three-way valve, fills the small gas chamber a, and drives the volatile residual solvents acetone, tetrahydrofuran, ethyl acetate and toluene to be detected in the concentrated extract in the small gas chamber a to pass through the GC sample inlet, flow through the chromatographic column and be analyzed by the GC instrument; the extractant n-hexane-3-methylimidazole hexafluorophosphate room temperature ionic liquid in the concentrated extraction liquid in the small air chamber A is completely adsorbed by the filter cotton 7 and is completely retained in the separator, and the pre-column separation of the extractant is completely realized.
Mounting and using methods of the separator:
when the separator 200 in this embodiment is used, the pointed needle 5 fixedly disposed at the center of the base 3 is inserted into the sample inlet 100 of the GC instrument, and thus the whole separator is mounted on the GC instrument.
The method for feeding the extraction concentrate into the separator 200 comprises the following steps: the needle of the microsyringe 46 is inserted into the central hole 11 in the screw cap 1, and then passes through the sample injection sealing gasket 6 in the three-way joint 2 to enter the small air chamber A; and opening a valve of the carrier gas steel cylinder, controlling the pressure of the carrier gas steel cylinder by using a chemical workstation equipped with a GC instrument, and enabling the carrier gas to flow through a carrier gas pipe, flow into the separator from the three-way joint 2 and fill the small gas chamber A.
Injecting the micro-sampler 46 to extract the concentrated solution, and making the concentrated solution enter the small air chamber A of the separator; the volatile residual solvents acetone, tetrahydrofuran, ethyl acetate and toluene to be detected in the extraction concentrated solution in the small air chamber A are driven by the carrier gas, flow through the GC sample inlet, flow into the chromatographic column and are subjected to GC analysis.
Step four, residual solvent GC analysis:
(1) selecting a chromatographic column:
in order to thoroughly separate residual solvents of acetone, tetrahydrofuran, ethyl acetate and toluene from an organic solvent medium of dimethyl sulfoxide, a capillary gas chromatographic column is adopted for research, and the technical indexes of the capillary gas chromatographic column with the type InertCap 17 are as follows: the stationary phase is 50% phenyl and 50% methyl, the column length is 30m, the inner diameter is 0.53mm, and the film thickness is 1.00 μm.
(2) Optimizing chromatographic conditions:
taking nitrogen as a carrier gas, and the chromatographic conditions are as follows: pressure 20.7KPa, total flow 16.5mL/min, column flow 4.51mL/min, linear flow rate 32.6cm/sec, purge flow 3.0mL/min, split ratio 2: 1;
temperature programming: initial temperature of 40 deg.C (1min), heating to 60 deg.C at 5 deg.C/min, heating to 90 deg.C at 30 deg.C/min, and heating to 190 deg.C at 50 deg.C/min (1 min);
the temperature of a sample inlet is 120 ℃; flame Ionization Detector (FID) temperature 250 deg.C, hydrogen flow 40.0mL/min, and air flow 400.0 mL/min.
(3) Recording a chromatogram:
firstly, extracting and concentrating residual solvents to be detected in a standard solution and a sample solution under the optimal extraction condition, then carrying out pre-column separation on an extracting agent n-hexane-3-methylimidazolium hexafluorophosphate room temperature ionic liquid in a concentrated solution, and finally carrying 4 residual solvents in the extracted concentrated solution into a GC instrument by carrier gas for chromatographic analysis. And (3) operating according to a set programmed heating mode, separating 4 residual solvents of acetone, tetrahydrofuran, ethyl acetate, toluene and solvent medium dimethyl sulfoxide, and recording a chromatogram. The standard solution chromatogram is shown in FIG. 12, and the sample solution chromatogram is shown in FIG. 13.
In FIG. 12, 1, 2, 3, 4 and 5 are acetone, tetrahydrofuran and acetic acid in the standard solution in sequenceChromatographic peaks of ethyl ester, toluene and dimethyl sulfoxide and retention time t of the chromatographic peaksRRespectively at 2.648min, 3.948min, 4.387min, 6.635min and 9.018 min. In FIG. 13, 1 and 5 are the acetone and dimethyl sulfoxide chromatographic peaks in sequence in the sample solution, and their retention times tR2.648min and 9.018min respectively; the ethyl acetate content is low, chromatographic peaks are not obvious, and tetrahydrofuran and toluene are not detected.
It can be seen from this that: the 4 residual solvents of acetone, tetrahydrofuran, ethyl acetate, toluene and solvent medium dimethyl sulfoxide are well separated and do not interfere with each other, the separation degree of each peak is more than 1.5, and the method conforms to the regulations of Chinese pharmacopoeia, American pharmacopoeia and European pharmacopoeia.
(4) Test methods investigation:
1, investigating enrichment multiple and linear relation:
10.00mL of standard solutions with different concentrations are extracted and concentrated according to the optimized LPME condition, sample injection analysis is carried out according to the optimized chromatographic condition, and each concentration is parallelly determined for 3 times. The linear relationship between the peak areas (A) of acetone, tetrahydrofuran, ethyl acetate and toluene and the concentration (C) of the standard solution and the enrichment times are measured, and the results are shown in Table 1.
TABLE 1 Linear relationship and detection limits
| Solvent(s) | Regression equation | Coefficient of correlation r | Linear Range (μ g/mL) | Multiple of enrichment |
| Acetone (II) | A＝38.498C+12.051 | 0.99951 | 0.292～62.98 | 76 |
| Tetrahydrofuran (THF) | A＝58.194C+10.214 | 0.99962 | 0.105～36.0 | 150 |
| Ethyl acetate | A＝47.374C+9.936 | 0.99941 | 0.0987～50.0 | 252 |
| Toluene | A＝43.499C+10.385 | 0.99970 | 0.1154～43.30 | 110 |
Investigation of detection limit and quantitative limit of the method:
diluting the standard stock solution with dimethyl sulfoxide step by step, extracting and concentrating according to optimized LPME conditions, and carrying out sample injection analysis according to optimized chromatographic conditions. The quantitative limit of acetone, tetrahydrofuran, ethyl acetate and toluene is respectively measured in parallel for 9 times under the condition that S/N is more than or equal to 10, and the detection limit of acetone, tetrahydrofuran, ethyl acetate and toluene is respectively measured in parallel for 9 times under the condition that S/N (signal to noise ratio) is more than or equal to 3. After blank values were subtracted, the quantitative limit concentrations and detection limit concentrations of acetone, tetrahydrofuran, ethyl acetate and toluene were determined, and the results are shown in Table 2.
TABLE 2 quantification and detection limits
| Solvent(s) | Limit of quantitation (ug/mL) | Detection limit (μ g/mL) |
| Acetone (II) | 0.4786 | 0.292 |
| Tetrahydrofuran (THF) | 0.1750 | 0.105 |
| Ethyl acetate | 0.1645 | 0.0987 |
| Toluene | 0.2098 | 0.1154 |
Investigating the content and precision of the sample:
precisely weighing 7 parts of a certain batch of toremifene citrate raw material drug with the weight of 0.1000 +/-0.0010 g for measuring the content of acetone; precisely weighing 7 parts of the same batch of 1.7500 +/-0.0010 g of raw material medicine for determining the content of tetrahydrofuran, ethyl acetate and toluene. 10.00mL of dimethyl sulfoxide was added to the mixture, the mixture was sealed with a cap, and the mixture was dissolved by shaking. Extracting and concentrating according to optimized LPME conditions, injecting and analyzing according to optimized chromatographic conditions, and respectively showing the measurement results in tables 3 and 4.
TABLE 3 determination of the amount of acetone remaining in the samples
TABLE 4 measurement of the residual amount of ethyl acetate in the samples
The detection shows that tetrahydrofuran and toluene are not detected in the sample, the average residue of acetone and ethyl acetate is 612.4 mug/g and 0.5666 mug/g, the RSD values are 1.128% and 3.303%, respectively, and the repeatability is good.
Recovery experiment:
recovery experiments were performed using standard addition methods. Precisely weighing the samples, controlling the quality to be 0.1001-0.1002 g, adding 10.00mL of dimethyl sulfoxide to dissolve, and then covering and sealing. Extracting and concentrating according to optimized LPME conditions, carrying out sample injection analysis according to optimized chromatographic conditions, and carrying out parallel determination for 5 times. The measurement results are shown in tables 5, 6, 7 and 8.
TABLE 5 determination of acetone recovery
As can be seen from Table 5, the low, medium and high recovery rates of acetone are respectively 98.74% -102.0%, 99.59% -101.1% and 99.67% -101.0%.
TABLE 6 determination of ethyl acetate recovery
As can be seen from Table 6, the low, medium and high recovery rates of ethyl acetate are respectively 98.88% -100.1%, 98.86% -100.3% and 98.93% -100.8%.
TABLE 7 determination of toluene recovery
As can be seen from Table 7, the low, medium and high recovery rates of toluene are 99.19% -102.1%, 98.83% -101.4% and 99.09% -101.7%, respectively.
TABLE 8 determination of tetrahydrofuran recovery
As can be seen from Table 8, the low, medium and high recovery rates of tetrahydrofuran were 99.39% -100.6%, 99.22% -100.5% and 99.36% -100.3%, respectively.
In summary, the method for determining residual solvents of acetone, tetrahydrofuran, ethyl acetate and toluene in the toremifene citrate bulk drug by the room-temperature ionic liquid pre-column separation LPME-GC method disclosed by the patent has the advantages of low detection limit, good accuracy and high precision.
Compared with the prior art, the invention has the advantages that:
firstly, the room-temperature ionic liquid extractant is subjected to pre-column separation, so that the room-temperature ionic liquid is prevented from damaging a chromatographic column, the room-temperature ionic liquid extractant which has a good extraction effect on trace volatile organic compounds but can damage the chromatographic column can also be used for an LPME-GC method, and the extractant selection range of the LPME-GC method is expanded;
secondly, pre-column separation of the extractant is combined with LPME extraction technology and GC analysis, an LPME-GC method for pre-column separation of the extractant is initiated, trace volatile organic compounds are determined in a non-aqueous system for the first time, the blank that the LPME-GC method is used for determining the trace volatile organic compounds in an organic non-aqueous system is filled, and a solid foundation is laid for expanding the application range of the LPME-GC method;
research results of LPME-GC method for separating normal hexane-3-methylimidazole hexafluorophosphate at room temperature in front of ionic liquid column to determine residual solvents of acetone, tetrahydrofuran, ethyl acetate and toluene in toremifene citrate bulk drug in non-aqueous system show that: the separation degree of the 4 residual solvents and the solvent medium accords with the regulations of Chinese pharmacopoeia, American pharmacopoeia and European pharmacopoeia, the enrichment multiple is far higher than that of a common organic extractant, the method has high sensitivity, the detection limit is lower than that of an HS-GC (static headspace gas chromatography) method, the linearity is good, the precision is high, the method is superior to the HS-GC method, the residual solvents can be measured by replacing the HS-GC method, the high cost required by purchasing a headspace instrument is avoided, the economic value of popularization is achieved, and the method for detecting trace volatile organic compounds by separating the LPME-GC method before the room-temperature ionic liquid column is also verified to be effective and feasible.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the technical principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A method for measuring residual solvent in a synthetic drug based on pre-column separation is characterized by sequentially comprising the following four steps:
step one, preparing a sample solution:
the synthetic drug is toremifene citrate, the drug is dissolved by an organic solvent medium dimethyl sulfoxide, and the residual solvent is acetone, tetrahydrofuran, ethyl acetate and toluene;
step two, LPME extraction, and preparation of concentrated solution:
the LPME technology is a hollow fiber membrane liquid-liquid two-phase liquid phase microextraction method, and the extractant is n-hexane-3-methylimidazole hexafluorophosphate room-temperature ionic liquid;
step three, separating the extractant before column:
separating the extractant in front of the column by using a separator, wherein filter cotton for preventing the extractant from entering the chromatographic column is arranged in the separator;
step four, residual solvent GC analysis:
and the residual solvent in the concentrated solution is driven by the carrier gas, flows through the sample inlet of the GC instrument, flows into the GC instrument and then is subjected to chromatographic analysis.
2. The method for determining the residual solvent in the synthetic drugs based on the pre-column separation as claimed in claim 1, wherein the filter cotton is 1-3 μm quartz cotton dedicated to the elemental analyzer, and the filter cotton is replaceable.
3. The method for determining the residual solvent in the synthetic drugs based on pre-column separation as claimed in claim 1, wherein the separator is installed at the front end of the sample inlet of the gas chromatograph, the separator comprises a screw cap, a three-way joint and a base which are sequentially assembled from top to bottom, and a small air chamber is formed in the three-way joint after the screw cap, the three-way joint and the base are assembled; the inlet port that is linked together with little air chamber is seted up to one side of three way connection, and inlet port outside department is equipped with the joint that is used for with gas circuit three way valve connection, and the lower extreme central point of base puts vertically to set up the aperture that is linked together with little air chamber, and aperture department integral type is fixed with the tip syringe needle that is used for can the disect insertion gas chromatograph inlet, the filter pulp locate in the base, the top of tip syringe needle.
4. The method according to claim 3, wherein a stepped slot is formed in the middle of the upper end of the base of the separator, the stepped slot being divided into three sections with a wide upper section and a narrow lower section, the inner wall of the upper section of the stepped slot being provided with an internal thread, the middle section of the tee being provided with an internal bore extending therethrough in the axial direction, the lower end of the tee being provided with a reduced diameter section engaged with the stepped slot, the reduced diameter section being divided into an upper section and a lower section, the upper section being an external thread section engaged with the internal thread of the stepped slot, the lower section being a cylindrical section corresponding to the middle section of the stepped slot, and the lower end of the tee being engaged with the base in the base and being fixed to the base by the threaded connection.
5. The method for measuring the residual solvent in the synthetic drugs based on the pre-column separation as claimed in claim 4, wherein the filter cotton is arranged in the lower groove of the stepped slot hole of the base and above the small hole of the base; an O-shaped sealing ring made of polytetrafluoroethylene materials is lined between the top of the external thread section of the three-way joint and the inner wall of the base.
6. The method according to claim 3, wherein a center hole is axially formed at a center of a screw cap of the separator, the center hole allowing insertion of the microsyringe therethrough, a reduced-diameter male screw connection post is formed at a lower end of the screw cap, a female screw connection groove corresponding to the male screw connection post of the screw cap is concavely formed in a middle of an upper end surface of the three-way connector, a groove is formed between a lower end of the female screw connection groove of the three-way connector and the inner hole, a sample injection gasket is disposed in the groove, and the screw cap is screwed and fixed to an upper end of the three-way connector in a screw connection manner and abuts against an upper end of the sample injection gasket for sealing.
7. The method for determining the residual solvent in the synthetic drugs based on pre-column separation as claimed in claim 3, wherein the air inlet of the separator is provided at one side of the middle of the tee joint along the radial direction of the tee joint, and the air inlet is communicated with the inner hole of the tee joint, the joint is a double-clamping sleeve turning outer cone threaded joint made of brass H62, and the joint is installed at the air inlet in a threaded connection manner.
8. The method for measuring the residual solvent in the synthetic drug based on pre-column separation according to any one of claims 1 to 7, wherein in the first step, the organic solvent is one of methanol, dimethylsulfoxide, N-dimethylformamide and N, N-dimethylacetamide.
9. The method for determining the residual solvent in the synthetic drug based on pre-column separation according to any one of claims 1 to 7, wherein in the second step, the hollow fiber tube in the liquid phase micro-extraction device is a polypropylene hollow fiber tube with the wall thickness of 180 to 220 μm, the pore diameter of 0.19 to 0.21 μm and the inner diameter of 550 to 650 μm; the extraction conditions comprise extraction heating temperature of 26.5-29.5 ℃, extraction heating time of 5-10 min and stirring speed of 800-1000 r/min.
10. The method for measuring the residual solvent in the synthetic drug based on the pre-column separation according to any one of claims 1 to 7, wherein in the fourth step, the chromatographic column used in the gas chromatograph is a capillary gas chromatographic column, and the detector used in the gas chromatograph is a flame ionization detector.
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| CN117686638A (en) * | 2024-02-04 | 2024-03-12 | 中国科学院合肥物质科学研究院 | Detection device and detection method for residual solvent in solid medicine |
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