Sample pre-concentration and separation system and method for measuring trace substances in environmental water body

Abstract

The invention discloses a sample pre-concentration and separation system and method for measuring trace substances in an environmental water body, belongs to the field of detection of trace gas dissolved in a water body, and aims to solve the technical problems of low separation degree and sensitivity of single equipment in the prior art. The device comprises a gas sample introduction module, a sample quantification module, a water sample pretreatment module, a trapping analysis module and a separation detection module. According to the invention, two sets of pre-column and analytical column systems are utilized to realize echelon separation of components with different properties, substances with different separation activities can realize respective effective separation under flow path switching, confusion caused by similar functional groups is effectively avoided, interference is eliminated, and the separation degree and measurement sensitivity of a target object are improved; meanwhile, two sets of detectors are adopted, so that the detection requirements of different sensitivities can be met.

Description

Technical Field

[0001] The present invention relates to the field of detection of trace gases dissolved in water, and in particular to a sample pre-concentration and separation system and method for measuring trace substances in environmental water. Background Art

[0002] Since the entry into force of the Montreal Protocol, the production and application of major chlorofluorocarbons (CFCs) and other chlorine- and bromine-containing compounds have been gradually banned and phased out. The current alternative substances are hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs). As a long-term substitute for chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), the abundance of hydrofluorocarbons (HFCs) in the atmosphere continues to rise rapidly, and promotes the enhancement of radiative forcing. Perfluorocarbons (PFCs) and sulfur hexafluoride (SF6) have an atmospheric lifetime of up to thousands of years. Together with hydrofluorocarbons (HFCs), they are three of the six major greenhouse gases targeted by the Kyoto Protocol. These substances also enter the water environment through atmospheric circulation, water cycle and other processes. Therefore, high-quality and high-resolution detection of these substances is crucial.

[0003] However, the current problem is that in water environments, these substances have different physical properties and their solubility in water varies greatly, with concentrations ranging from fmol / L (10-15) to μmol / L (10-6). Different equipment is often required to achieve the enrichment, separation and detection of a series of substances. Even if a single device can separate more target substances, its separation degree and sensitivity are low, so it cannot meet monitoring needs.

[0004] Therefore, a system is urgently needed to achieve the enrichment and separation of the above-mentioned trace halogenated hydrocarbons, hydrocarbons and sulfides. Summary of the invention

[0005] The object of the present invention is to provide a sample pre-concentration and separation system and method for measuring trace substances in environmental water bodies, so as to solve the technical problem of low separation degree and sensitivity of a single device in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions: The present invention provides a sample pre-concentration and separation system for measuring trace substances in environmental water, comprising: A gas injection module, which is used to provide standard gas, purge gas and introduce sample source into the system; A sample quantification module, the gas sampling module is connected to the sample quantification module, and the sample quantification module includes a plurality of quantitative loops and a plurality of multi-way valves connected in series, for controlling and adjusting the sample amount; A water sample pretreatment module, the water sample pretreatment module comprising a purge pipe, a drying and acid removal pipe 1, a drying and acid removal pipe 2, and a plurality of multi-way valves; A capture and analysis module, wherein the gas sampling module and the water pretreatment module are respectively connected to the capture and analysis module, and the capture and analysis module comprises a front capture tube, a rear capture tube and a plurality of multi-way valves for achieving enrichment, cold focusing and transfer of the target; The separation and detection module comprises a pre-column 1, a pre-column 2, an analytical column 1, an analytical column 2 and a plurality of multi-way valves, and is used to separate and detect the target.

[0007] Optionally or preferably, the gas sampling module comprises a nitrogen input pipeline, a nitrogen purification pipe, a pressure regulator and a multi-way valve; The output end of the pressure regulator is connected to gas circuit 1, gas circuit 2, gas circuit 3, gas circuit 4, gas circuit 5, gas circuit 6 and gas circuit 7 respectively; the gas circuit 1 is connected to the input end of the multi-way valve 1, the gas circuit 2 is connected to the sample quantification module, and the gas circuit 3, gas circuit 4, gas circuit 5, gas circuit 6 and gas circuit 7 are respectively connected to the capture and analysis module and / or the separation and detection module; The input end of the multi-way valve 1 is also connected to an air sample inlet pipeline and a plurality of standard gas inlet pipelines respectively; the output end of the multi-way valve 1 is connected to the sample quantification module.

[0008] Optionally or preferably, the sample quantification module comprises a multi-way valve 11, a multi-way valve 12, a multi-way valve 13 and a multi-way valve 14 connected in series in sequence; The gas circuit 2 is connected to the multi-way valve 11, the multi-way valve 12, the multi-way valve 13, and the multi-way valve 14 in sequence and finally connected to the water sample pretreatment module; The output end of the multi-way valve 1 is connected to the multi-way valve 11, the multi-way valve 12, the multi-way valve 13, and the multi-way valve 14 in sequence and finally connected to the exhaust port.

[0009] Optionally or preferably, the water sample pretreatment module includes a multi-way valve 2, a multi-way valve 3 and a multi-way valve 15; The multi-way valve 15 is used to control the water sample to flow into or out of the purge pipe; The multi-way valve 2 is used to balance the pressure difference in the purge pipe during the process of the water sample entering the purge pipe; The multi-way valve three is used to switch the purge gas through the purge pipe or bypass.

[0010] Optionally or preferably, the capture and analysis module includes a multi-way valve four, a multi-way valve five, a multi-way valve six, a multi-way valve seven and a multi-way valve eight; The front collecting tube includes a collecting tube 1, and the rear collecting tube includes a collecting tube 2 and a collecting tube 3; The separation detection module also includes a multi-way valve nine and a multi-way valve ten; The pre-column one is connected to the system through the multi-way valve nine; the analytical column one and the detector one are connected to the system through the multi-way valve ten; the analytical column two and the detector two are connected to the system through the multi-way valve eight.

[0011] Optionally or preferably, the multi-way valve six, multi-way valve eight, multi-way valve nine and multi-way valve ten are two-position four-way valves, each including a working port a, a working port b, a working port c, a working port d and a first working state and a second working state; When the multi-way valve 6 and the multi-way valve 8 are in the first working state, the working port a is connected to the working port b, and the working port c is connected to the working port d; when the multi-way valve 6 and the multi-way valve 8 are in the second working state, the working port a is connected to the working port d, and the working port b is connected to the working port c; when the multi-way valve 9 and the multi-way valve 10 are in the first working state, the working port a is connected to the working port d, and the working port b is connected to the working port c; when the multi-way valve 9 and the multi-way valve 10 are in the second working state, the working port a is connected to the working port b, and the working port c is connected to the working port d; The multi-way valve 3, the multi-way valve 4 and the multi-way valve 5 are two-position six-way valves, each including a working port a, a working port b, a working port c, a working port d, a working port e, a working port f and a first working state and a second working state; When the multi-way valve 3, the multi-way valve 4 and the multi-way valve 5 are in the first working state, the working port a is connected with the working port b, the working port c is connected with the working port d, and the working port e is connected with the working port f; when the multi-way valve 3, the multi-way valve 4 and the multi-way valve 5 are in the second working state, the working port a is connected with the working port f, the working port b is connected with the working port c, and the working port d is connected with the working port e; The multi-way valve seven is a two-position eight-way valve, including a working port a, a working port b, a working port c, a working port d, a working port e, a working port f, a working port g and a working port h; when the multi-way valve seven is in a first working state, the working port a is connected to the working port h, the working port b is connected to the working port c, the working port d is connected to the working port e, and the working port f is connected to the working port g; when the multi-way valve seven is in a second working state, the working port a is connected to the working port b, the working port c is connected to the working port d, the working port e is connected to the working port f, and the working port g is connected to the working port h; The sample pre-concentration and separation system for measuring trace substances in environmental water includes a tracer detection mode and a full substance mode. When the system is in the tracer detection mode, the flow path is in a first ready state, and when the system is in the full substance mode, the flow path is in a second ready state; In the first ready state, multi-way valve 3, multi-way valve 4, multi-way valve 5, multi-way valve 7 and multi-way valve 8 are all in the first working state; multi-way valve 6, multi-way valve 9 and multi-way valve 10 are in the second working state; In the second ready state, the multi-way valve three, the multi-way valve four, the multi-way valve five, the multi-way valve six, the multi-way valve seven and the multi-way valve eight, the multi-way valve nine and the multi-way valve ten are all in the first working state.

[0012] A method for measuring trace substances in environmental water, when the system is in a tracer detection mode, includes the following process: Water sample purge process: switch the flow path to the water sample purge state, at this time, multi-way valve seven and multi-way valve eight are in the first working state; multi-way valve three, multi-way valve four, multi-way valve five, multi-way valve six, multi-way valve nine, and multi-way valve ten are in the second working state; The purge gas passes through the multi-way valve 11, the multi-way valve 12, the multi-way valve 13, the multi-way valve 14 and the multi-way valve 3 from the gas path 2 and then enters the purge pipe. After passing through the water sample, the target gas is formed and passes through the multi-way valve 2, the drying and acid removal pipe 1, the multi-way valve 3 and the drying and acid removal pipe 2 in sequence. After the target gas removes the acid gas in the drying and acid removal pipe 2, it enters the capture pipe 1 through the multi-way valve 4. After the target is captured by the capture pipe 1, the remaining gas flows out of the capture pipe 1 and is discharged from the exhaust port after passing through the multi-way valve 5. Desorption process: switch the flow path to the desorption state of the capture tube 1, at which time the multi-way valve 3, the multi-way valve 4, the multi-way valve 5, the multi-way valve 6, and the multi-way valve 8 are in the first working state; the multi-way valve 7, the multi-way valve 9, and the multi-way valve 10 are in the second working state; The temperature of the trapping tube 1 is raised, and the carrier gas passes through the multi-way valve 6, the multi-way valve 5, the trapping tube 1, the multi-way valve 4, the multi-way valve 9, the pre-column 1, the multi-way valve 9, the multi-way valve 6, the multi-way valve 7 and the trapping tube 2 in sequence from the gas path 4; the target is desorbed from the trapping tube 1, and pre-separated in the pre-column 1, and the target component 1 with a shorter retention time preferentially enters the trapping tube 2 and is cold-focused in the trapping tube 2, and the remaining gas is discharged through the exhaust port; Injection process: switch the flow path to the injection state, at this time, multi-way valve 3, multi-way valve 4, multi-way valve 5, multi-way valve 6, and multi-way valve 7 are in the first working state; multi-way valve 8, multi-way valve 9, and multi-way valve 10 are in the second working state; At this time, the carrier gas passes through the multi-way valve 6, the multi-way valve 5, the trapping tube 1, the multi-way valve 4, the multi-way valve 9, the pre-column 1, the multi-way valve 9, the multi-way valve 6, the multi-way valve 7, the multi-way valve 10, the trapping tube 3 and the analytical column 1 from the gas path 4 in sequence; the target component 2 with a longer retention time flows out of the pre-column 1 at this time, follows the gas path into the trapping tube 3 and is cold-focused in the trapping tube 3; After the target component 2 is cryofocused in the capture tube 3, the capture tube 3 is heated up, and the target component 2 then enters the analytical column 1 for separation and purification, and finally enters the detector 1 for detection with the target; At the same time, another carrier gas passes through the gas path 5 through the multi-way valve 8 and passes through the trapping tube 2 in the reverse direction, desorbs the target component 1 from the trapping tube 2, and enters the pre-column 2 through the multi-way valve 7 along the gas path, and then passes through the multi-way valve 8 and is separated and purified in the analytical column 2, and finally carries the target into the detector 2 for detection; Optionally or preferably, when the system is in the tracer detection mode, it also includes a backflush process: switching the flow path to the backflush state, at which time the multi-way valve three and the multi-way valve eight are in the first working state; the multi-way valve four, the multi-way valve five, the multi-way valve six, the multi-way valve seven, the multi-way valve nine, and the multi-way valve ten are in the second working state; At this time, the backflush gas passes through the multi-way valve five, the multi-way valve six, the multi-way valve nine, the pre-column one, the multi-way valve nine, the multi-way valve four in sequence from the gas line three, and then is discharged through the exhaust port; At the same time, backflush 7 passes through multi-way valve 11, multi-way valve 12, multi-way valve 13, multi-way valve 14, multi-way valve 3, multi-way valve 4, trapping pipe 1 and multi-way valve 5 from gas path 2 in sequence, and then is emptied through the exhaust port; At the same time, the backflush gas passes through the multi-way valve six, the multi-way valve seven, the capture tube two, the multi-way valve eight, the pre-column two, the multi-way valve seven in sequence from the gas line four, and then is discharged through the exhaust port.

[0013] Optionally or preferably, when the system is in full substance mode, the following processes are included: Water sample purge process: switch the flow path to the water sample purge state, at this time, multi-way valve seven, multi-way valve eight, multi-way valve nine, and multi-way valve ten are in the first working state; multi-way valve three, multi-way valve four, multi-way valve five, and multi-way valve six are in the second working state; The purge gas passes through the multi-way valve 11, the multi-way valve 12, the multi-way valve 13, the multi-way valve 14 and the multi-way valve 3 from the gas path 2 and then enters the purge pipe. After passing through the water sample, the target gas is formed and passes through the multi-way valve 2, the drying and acid removal pipe 1, the multi-way valve 3 and the drying and acid removal pipe 2 in sequence. After the target gas removes the acid gas in the drying and acid removal pipe 2, it enters the capture pipe 1 through the multi-way valve 4. After the target is captured by the capture pipe 1, the remaining gas flows out of the capture pipe 1 and is discharged from the exhaust port after passing through the multi-way valve 5. Desorption process: switch the flow path to the desorption state of the capture tube 1, at this time, the multi-way valve 3, the multi-way valve 4, the multi-way valve 5, the multi-way valve 6, the multi-way valve 8, the multi-way valve 9, and the multi-way valve 10 are in the first working state; the multi-way valve 7 is in the second working state; The temperature of the trapping tube 1 is raised, and the carrier gas passes through the multi-way valve 6, the multi-way valve 5, the trapping tube 1, the multi-way valve 4, the multi-way valve 9, the multi-way valve 6, the multi-way valve 7, the trapping tube 2, the multi-way valve 8, the pre-column 2 and the multi-way valve 7 from the gas path 4 in sequence; the target is desorbed from the trapping tube 1, and pre-separated in the pre-column 2, and the remaining gas passes through the multi-way valve 7 and is discharged from the exhaust port; Injection process: switch the flow path to the injection state, at this time, multi-way valve three, multi-way valve four, multi-way valve five, multi-way valve six, multi-way valve seven, multi-way valve nine, and multi-way valve ten are in the first working state; multi-way valve eight is in the second working state; The carrier gas passes through the gas line five through the multi-way valve eight and then passes through the capture tube two in the reverse direction, and enters the pre-column two through the multi-way valve seven along the gas line, and then passes through the multi-way valve eight to be separated and purified in the analytical column two, and finally carries the target substance into the detector two for detection.

[0014] Optionally or preferably, when the system is in the full substance mode, it also includes a backflush process: switching the flow path to the backflush state, at which time the multi-way valve three, the multi-way valve eight, the multi-way valve nine, and the multi-way valve ten are in the first working state; the multi-way valve four, the multi-way valve five, the multi-way valve six, and the multi-way valve seven are in the second working state; At this time, the back-blowing gas passes through the multi-way valve five, the multi-way valve six, the multi-way valve nine, the multi-way valve four in sequence from the gas path three, and then is discharged through the exhaust port; At the same time, backflush 7 passes through multi-way valve 11, multi-way valve 12, multi-way valve 13, multi-way valve 14, multi-way valve 3, multi-way valve 4, trapping pipe 1 and multi-way valve 5 from gas path 2 in sequence, and then is emptied through the exhaust port; At the same time, the backflush gas passes through the multi-way valve six, the multi-way valve seven, the capture tube two, the multi-way valve eight, the pre-column two, the multi-way valve seven in sequence from the gas line four, and then is discharged through the exhaust port.

[0015] Based on the above technical solution, the present invention can at least produce the following technical effects: The present invention provides a sample pre-concentration and separation system and method for measuring trace substances in environmental water bodies, which adopts multiple sets of capture tubes to meet the enrichment needs of large-volume samples, and uses cold focusing (secondary capture) to achieve narrowing of the target object spectral band, thereby improving the sensitivity and separation effect of subsequent separation and detection.

[0016] By using two sets of pre-column and analytical column systems, the step-by-step separation of components with different properties is achieved. Substances with different separation activities can be effectively separated under flow switching, which effectively avoids confusion caused by similar functional groups, eliminates interference, and improves the separation degree and measurement sensitivity of the target. At the same time, two sets of detectors are used to meet the needs of detection with different sensitivities.

[0017] In addition, through the combination of multiple sample quantitative loops, the quantitative combination of low-boiling point volatile trace gas standards with different contents can be achieved without changing the standard concentration, thus realizing batch external standard calibration; through the glass purge tube with volume calibration, the water sample injection volume can be directly read without additional measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a flow path arrangement diagram of the first ready state when the system of the present invention is in a tracer detection mode; Figure 2 It is a flow path arrangement diagram of a water sample purge state when the system of the present invention is in a tracer detection mode; Figure 3 is a flow path arrangement diagram of the desorption state when the system of the present invention is in the tracer detection mode; Figure 4 It is a flow path arrangement diagram of the sample injection state when the system of the present invention is in the tracer detection mode; Figure 5 is a flow path arrangement diagram of a backflush state when the system of the present invention is in a tracer detection mode; Figure 6 is a flow path arrangement diagram of the second ready state when the system of the present invention is in full substance mode; Figure 7 It is a flow path arrangement diagram of a water sample purge state when the system of the present invention is in a full substance mode; Figure 8 It is a flow path arrangement diagram of the desorption state when the system of the present invention is in the full material mode; Fig. 9 It is a flow path arrangement diagram of the injection state when the system of the present invention is in the full substance mode; Fig.10 It is a flow path arrangement diagram of the backflush state when the system of the present invention is in the full substance mode; Fig.11 This is a schematic diagram of the working port arrangement of the two-position four-way valve in the present invention. Figure 1 ; Fig.12 This is a schematic diagram of the working port arrangement of the two-position four-way valve in the present invention. Figure 2 ; Fig.13 It is a schematic diagram of the arrangement of the working ports of the two-position six-way valve in the present invention; Fig.14 It is a schematic diagram of the arrangement of the working ports of the two-position eight-way valve in the present invention.

[0019] In the figure: 1. pressure gauge; 2. switch valve; 3. filter; 4. drying and acid removal tube 1; 5. drying and acid removal tube 2; 6. pre-column 1; 7. pre-column 2; 8. analytical column 1; 9. analytical column 2; 10. nitrogen input pipeline; 11. nitrogen purification pipe; 12. pressure regulator; 13. air sample inlet pipeline; 14. standard gas inlet pipeline; 15. purge pipe; 16. capture tube 1; 17. capture tube 2: 18. capture tube 3; 19. detector 1; 20. detector 2; V1, multi-way valve one; V2, multi-way valve two; V3, multi-way valve three; V4, multi-way valve four; V5, multi-way valve five; V6, multi-way valve six; V7, multi-way valve seven; V8, multi-way valve eight; V9, multi-way valve nine; V10, multi-way valve ten; V11, multi-way valve eleven; V12, multi-way valve twelve; V13, multi-way valve thirteen; V14, multi-way valve fourteen; V15, multi-way valve fifteen; L1, gas circuit 1; L2, gas circuit 2; L3, gas circuit 3; L4, gas circuit 4; L5, gas circuit 5; L6, gas circuit 6; L7, gas circuit 7; P1, emptying port one; P2, emptying port two; P3, emptying port three; P4, emptying port four; P5, emptying port five; P6, emptying port six. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work belong to the scope of protection of the present invention. Example

[0021] See also Figures 1 to 10 A sample pre-concentration and separation system for measuring trace substances in environmental water bodies includes a gas injection module, a sample quantification module, a water sample pretreatment module, a capture and analysis module, and a separation and detection module that are interconnected.

[0022] In this embodiment, the gas sampling module is used to provide standard gas, purge gas and introduce sample source to the system, including nitrogen input pipeline 10, nitrogen purification pipe 11, pressure regulator 12 and multi-way valve V1. Nitrogen is input from nitrogen input pipeline 10, enters pressure regulator 12 for distribution after passing through nitrogen purification pipe 11. In this embodiment, pressure regulator 12 is provided with multiple output gas circuits, including gas circuit 1 L1, gas circuit 2 L2, gas circuit 3 L3, gas circuit 4 L4, gas circuit 5 L5, gas circuit 6 L6 and gas circuit Seven L7, wherein gas circuit one L1 is connected with a multi-way valve one V1, gas circuit L2 is connected with the above-mentioned sample quantification module, gas circuit three L3, gas circuit four L4 and gas circuit five L5 are respectively connected with the capture analysis module and / or separation detection module; the pressure regulator 12 provides purge gas and carrier gas to the system by controlling the above-mentioned multiple gas circuits; the input end of the multi-way valve one V1 is also connected with at least two standard gas inlet pipes 14 and an air sample inlet pipe 13, wherein the air sample inlet pipe 13 is also provided with a filter 3.

[0023] The sample quantification module includes multiple quantitative rings and a multi-way valve eleven V11, a multi-way valve twelve V12, a multi-way valve thirteen V13 and a multi-way valve fourteen V14 connected in series in sequence; the multiple quantitative rings can realize the quantitative combination of low-boiling point volatile trace gas standards with different contents, and the multiple multi-way valves connected in series can realize the injection of standard gases of different volumes.

[0024] In the present embodiment, the multi-way valve eleven V11, the multi-way valve twelve V12, the multi-way valve thirteen V13, and the multi-way valve fourteen V14 are respectively connected to a plurality of quantitative rings of different sizes, and the multi-way valve eleven V11, the multi-way valve twelve V12, the multi-way valve thirteen V13, and the multi-way valve fourteen V14 can realize the quantification of different gas sample injection volumes by switching the flow path; the multi-way valve eleven V11 is connected to the gas path one L1 through the multi-way valve one V1, and the end of the multi-way valve fourteen V14 is connected to the exhaust port two P2. At the front end of the exhaust port two P2, a precision pressure gauge 1 is also provided, and the pressure of the gas sample in the quantitative ring can be measured by the precision pressure gauge 1.

[0025] The water sample pretreatment module includes a glass purge tube 15 with a scale, a drying and acid removal tube 1 4, a drying and acid removal tube 2 5, a multi-way valve 2 V2, a multi-way valve 3 V3 and a multi-way valve 15 V15; wherein the multi-way valve 15 V15 is a three-way valve, used to control the water sample to flow into or out of the purge tube 15; the multi-way valve 2 V2 is used to balance the pressure difference in the purge tube 15 during the process of the water sample entering the purge tube 15; the multi-way valve 3 V3 is used to switch the purge gas through the purge tube 15 or bypass. Specifically, the purge tube 15 includes an upper end connection port, a lower end connection port and a side connection port, wherein the upper end connection port is connected to the multi-way valve 2 V2, the lower end connection port is connected to the multi-way valve 3 V3, and the side connection port is connected to the multi-way valve 15 V15.

[0026] In this embodiment, the drying and acid-removing tube 1 4 and the drying and acid-removing tube 2 5 both include a drying tube and an acid-removing tube, wherein the drying tube is filled with anhydrous magnesium perchlorate for absorbing moisture contained in the sample gas; the acid-removing tube is filled with silica gel particles coated with sodium hydroxide for absorbing acidic gases such as CO2 contained in the sample gas.

[0027] The capture and analysis module is used to achieve the enrichment, cold focusing and transfer of the target object; it includes capture tube one 16, capture tube two 17, capture tube three 18, multi-way valve four V4, multi-way valve five V5, multi-way valve six V6, multi-way valve seven V7 and multi-way valve eight V8; wherein the two ends of capture tube one 16 are respectively connected to multi-way valve four V4 and multi-way valve five V5, and the two ends of capture tube two 17 are respectively connected to multi-way valve seven V7 and multi-way valve eight V8.

[0028] In this embodiment, the first capture tube 16 is a front capture tube, the second capture tube 17 and the third capture tube 18 are rear capture tubes, and the inner diameter of the front capture tube is 2-3 times that of the rear capture tube; the target is first pre-enriched in the first capture tube 16, and then cold focused in the second capture tube 17 or the third capture tube 18. The above-mentioned capture tubes all have the ability to adjust the temperature, and the temperature can be adjusted according to the actual working needs, and the temperature adjustment range is -180°C to 300°C.

[0029] The separation and detection module is used to realize the detection and separation of the target object. In this embodiment, the separation and detection module includes a pre-column 16, a pre-column 27, an analytical column 18, an analytical column 29, a multi-way valve 9 V9 and a multi-way valve 10 V10; wherein the pre-column 16 is connected to the system through the multi-way valve 9 V9, the two ends of the pre-column 27 are respectively connected to the multi-way valve 7 V7 and the multi-way valve 8 V8, the analytical column 18 and the detector 19 are connected to the system through the multi-way valve 10 V10, and the analytical column 29 and the detector 20 are connected to the system through the multi-way valve 8 V8.

[0030] In this embodiment, the detector 1 19 and the detector 2 20 may be electron capture detectors (ECDs) that are sensitive to halogen compounds.

[0031] In addition, the multi-way valve nine V9 and the multi-way valve ten V10 are connected to the capture and analysis module through pipelines, which are used to switch the system mode and select whether the gas path passes through the pre-column one 6 and the analytical column one 19; when the system is in the tracer detection mode, the multi-way valve nine V9 and the multi-way valve ten V10 allow the gas path to pass through the pre-column one 6 to achieve the preliminary separation of the target; when the system is in the full substance mode, the gas path bypasses the multi-way valve nine V9 and the multi-way valve ten V10, the gas path does not pass through the pre-column one 6, and all substances are cold focused in the capture tube two 17.

[0032] See also Figure 11 to Figure 12 In this embodiment, the multi-way valve six V6, the multi-way valve eight V8, the multi-way valve nine V9 and the multi-way valve ten V10 are two-position four-way valves, each including a working port a, a working port b, a working port c, a working port d and a first working state and a second working state; When the multi-way valve six V6 and the multi-way valve eight V8 are in the first working state, the working port a is connected to the working port b, and the working port c is connected to the working port d; when the multi-way valve six V6 and the multi-way valve eight V8 are in the second working state, the working port a is connected to the working port d, and the working port b is connected to the working port c; When the multi-way valve nine V9 and the multi-way valve ten V10 are in the first working state, the working port a is connected to the working port d, and the working port b is connected to the working port c; when the multi-way valve nine V9 and the multi-way valve ten V10 are in the second working state, the working port a is connected to the working port b, and the working port c is connected to the working port d; See also Fig.13 , the multi-way valve three V3, the multi-way valve four V4, and the multi-way valve five V5 are two-position six-way valves, each including a working port a, a working port b, a working port c, a working port d, a working port e, a working port f, and a first working state and a second working state; When the multi-way valve three V3, the multi-way valve four V4, and the multi-way valve five V5 are in the first working state, the working port a is connected to the working port b, the working port c is connected to the working port d, and the working port e is connected to the working port f; when the multi-way valve three V3, the multi-way valve four V4, and the multi-way valve five V5 are in the second working state, the working port a is connected to the working port f, the working port b is connected to the working port c, and the working port d is connected to the working port e; See also Fig.14 , the multi-way valve V7 is a two-position eight-way valve, including a working port a, a working port b, a working port c, a working port d, a working port e, a working port f, a working port g and a working port h; when the multi-way valve V7 is in a first working state, the working port a is connected to the working port h, the working port b is connected to the working port c, the working port d is connected to the working port e, and the working port f is connected to the working port g; when the multi-way valve V7 is in a second working state, the working port a is connected to the working port b, the working port c is connected to the working port d, the working port e is connected to the working port f, and the working port g is connected to the working port h; In this embodiment, the sample pre-concentration and separation system for measuring trace substances in environmental water includes a tracer detection mode and a full substance mode. When the system is in the tracer detection mode, the flow path is in a first ready state; when the system is in the full substance mode, the flow path is in a second ready state; In the first ready state, the multi-way valve three V3, the multi-way valve four V4, the multi-way valve five V5, the multi-way valve seven V7 and the multi-way valve eight V8 are all in the first working state; the multi-way valve six V6, the multi-way valve nine V9 and the multi-way valve ten V10 are in the second working state; In the second ready state, the multi-way valve three V3, the multi-way valve four V4, the multi-way valve five V5, the multi-way valve six V6, the multi-way valve seven V7, the multi-way valve eight V8, the multi-way valve nine V9 and the multi-way valve ten V10 are all in the first working state.

[0033] The main difference between the above tracer detection mode and the full substance mode is that the working states of multi-way valve nine V9 and multi-way valve ten V10 are different. In the tracer detection mode, the target is divided into different components, and then separated and detected respectively after cold focusing (secondary enrichment) in two capture tubes, which effectively avoids confusion caused by similar functional groups, eliminates interference, and improves the separation and measurement sensitivity of the target. In the full substance mode, the system operates in the full substance mode, and all targets are detected simultaneously in one detector.

[0034] For ease of understanding, Figures 1 to 10 A working status table of multi-way valve three V3, multi-way valve four V4, multi-way valve five V5, multi-way valve six V6, multi-way valve seven V7, multi-way valve eight V8, multi-way valve nine V9 and multi-way valve ten V10 is given, wherein "A" indicates that the multi-way valve is in the first working state, and "B" indicates that the multi-way valve is in the second working state; in addition, for the convenience of description and to avoid lengthy instructions, the flow path switching method of multi-way valve one V1, multi-way valve two V2 and multi-way valve fifteen V15 is omitted, and the technical personnel can obtain the corresponding control method based on common knowledge.

[0035] In addition, in this embodiment, each component is connected through a pipeline, and a switch valve and a flow meter are provided at each exhaust port. Example

[0036] This embodiment provides a method for measuring trace substances in environmental water based on the first embodiment. It should be noted that for the sake of ease of description and understanding, the connection relationship between the gas circuit and the specific working ports in each multi-way valve is omitted in this embodiment, and those skilled in the art can easily find out the relationship by combining the drawings or common knowledge.

[0037] When the system is in tracer detection mode, the following process is involved: Water Sample Purge Procedure: Please refer to Figure 2 , the system switches the flow path from the first ready state to the water sample purge state, at this time, the multi-way valve seven V7 and the multi-way valve eight V8 are in the first working state; the multi-way valve three V3, the multi-way valve four V4, the multi-way valve five V5, the multi-way valve six V6, the multi-way valve nine V9, and the multi-way valve ten V10 are in the second working state; The purge gas passes through the multi-way valve eleven V11, the multi-way valve twelve V12, the multi-way valve thirteen V13, the multi-way valve fourteen V14, and the multi-way valve three V3 from the gas line two L2, and then enters the purge pipe 15. After passing through the water sample, the target gas is formed and passes through the multi-way valve two V2, the dry acid removal pipe one 4, the multi-way valve three V3 and the dry acid removal pipe two 5 in sequence; after the target gas removes the acid gas in the dry acid removal pipe two 5, it passes through the multi-way valve four V4 and enters the capture pipe one 16. At this time, the temperature of the capture pipe one 16 is -80°C, and the target is adsorbed by the capture pipe one 16. The remaining gas flows out of the capture pipe one 16, passes through the multi-way valve five V5, and is discharged from the exhaust port five P5; Desorption process: switch the flow path to the desorption state of the capture tube 16, at this time, the multi-way valve three V3, the multi-way valve four V4, the multi-way valve five V5, the multi-way valve six V6, and the multi-way valve eight V8 are in the first working state; the multi-way valve seven V7, the multi-way valve nine V9, and the multi-way valve ten V10 are in the second working state; The temperature of the trapping tube 16 is raised to 90°C. At this time, the carrier gas passes through the multi-way valve 6 V6, the multi-way valve 5 V5, the trapping tube 16, the multi-way valve 4 V4, the multi-way valve 9 V9, the pre-column 16, the multi-way valve 9 V9, the multi-way valve 6 V6, the multi-way valve 7 V7 and the trapping tube 2 17 in sequence from the gas line 4 L4; the target is desorbed from the trapping tube 16, and pre-separated in the pre-column 16. The target component 1 with a shorter retention time preferentially enters the trapping tube 2 17 and is cryofocused (secondary enrichment) in the trapping tube 2 17, and the remaining gas is discharged through the exhaust port 4 P4; Injection process: switch the flow path to the injection state, at this time, multi-way valve three V3, multi-way valve four V4, multi-way valve five V5, multi-way valve six V6, multi-way valve seven V7 are in the first working state; multi-way valve eight V8, multi-way valve nine V9, multi-way valve ten V10 are in the second working state; At this time, the carrier gas from gas line four L4 passes through multi-way valve six V6, multi-way valve five V5, capture tube one 16, multi-way valve four V4, multi-way valve nine V9, pre-column one 6, multi-way valve nine V9, multi-way valve six V6, multi-way valve seven V7, multi-way valve ten V10, capture tube three 18 and analytical column one 8 in sequence; target component two with a longer retention time flows out of pre-column one 6 at this time, follows the gas line into capture tube three 18 and is cold focused (secondary enrichment) in capture tube three 18. At this time, the temperature in capture tube three 18 is -80°C.

[0038] After the target component 2 is cryofocused in the capture tube 3 18, the capture tube 3 18 is heated to 90°C, and the target component 2 then enters the analytical column 1 8 for separation and purification, and finally enters the detector 19 for detection with the target; At the same time, another carrier gas passes through the gas line five L5 and the multi-way valve eight V8 in the reverse direction through the capture tube two 17. At this time, the temperature of the capture tube two 17 rises to 90°C, and the target component one is desorbed from the capture tube two 17, and enters the pre-column two 7 through the multi-way valve seven V7 with the gas line, and then passes through the multi-way valve eight V8 and is separated and purified in the analytical column two 9, and finally carries the target into the detector two 20 for detection.

[0039] Backflush process: switch the flow path to the backflush state, at this time, the multi-way valve three V3 and the multi-way valve eight V8 are in the first working state; the multi-way valve four V4, the multi-way valve five V5, the multi-way valve six V6, the multi-way valve seven V7, the multi-way valve nine V9, and the multi-way valve ten V10 are in the second working state; At this time, the backflush gas passes through the multi-way valve five V5, the multi-way valve six V6, the multi-way valve nine V9, the pre-column one 6, the multi-way valve nine V9, the multi-way valve four V4 from the gas line three L3 in sequence, and then is discharged through the exhaust port three P3; At the same time, backflush 7 passes through multi-way valve 11 V11, multi-way valve 12 V12, multi-way valve 13 V13, multi-way valve 14 V14, multi-way valve 3 V3, multi-way valve 4 V4, capture pipe 16 and multi-way valve 5 V5 from gas line 2 L2 in sequence, and then is emptied through exhaust port 5 P5; At the same time, the backflush gas passes through the multi-way valve six V6, the multi-way valve seven V7, the capture tube two 17, the multi-way valve eight V8, the pre-column two 7, the multi-way valve seven V7 from the gas line four L4 in sequence, and then is discharged through the exhaust port four P4.

[0040] When the system is in full substance mode, the following processes are included: Water sample purge process: switch the flow path to the water sample purge state, at this time, multi-way valve seven V7, multi-way valve eight V8, multi-way valve nine V9, multi-way valve ten V10 are in the first working state; multi-way valve three V3, multi-way valve four V4, multi-way valve five V5, multi-way valve six V6 are in the second working state; The purge gas passes through the multi-way valve eleven V11, the multi-way valve twelve V12, the multi-way valve thirteen V13, the multi-way valve fourteen V14, and the multi-way valve three V3 from the gas path two L2 in sequence and then enters the purge pipe 15. After passing through the water sample, the target gas is formed and passes through the multi-way valve two V2, the dry acid removal pipe one 4, the multi-way valve three V3 and the dry acid removal pipe two 5 in sequence; after the target gas removes the acid gas in the dry acid removal pipe two 5, it passes through the multi-way valve four V4 and enters the capture pipe one 16. After the target is captured by the capture pipe one 16, the remaining gas flows out of the capture pipe one 16 and is discharged from the exhaust port after passing through the multi-way valve five V5; Desorption process: switch the flow path to the desorption state of the capture tube 16, at this time, the multi-way valve three V3, the multi-way valve four V4, the multi-way valve five V5, the multi-way valve six V6, the multi-way valve eight V8, the multi-way valve nine V9, and the multi-way valve ten V10 are in the first working state; the multi-way valve seven V7 is in the second working state; The temperature of the trapping tube 16 is raised, and the carrier gas passes through the multi-way valve 6 V6, the multi-way valve 5 V5, the trapping tube 16, the multi-way valve 4 V4, the multi-way valve 9 V9, the multi-way valve 6 V6, the multi-way valve 7 V7, the trapping tube 2 17, the multi-way valve 8 V8, the pre-column 2 7 and the multi-way valve 7 V7 from the gas line 4 L4 in sequence; the target is desorbed from the trapping tube 16, and pre-separated in the pre-column 2 7, and the remaining gas passes through the multi-way valve 7 V7 and is discharged from the exhaust port; Injection process: switch the flow path to the injection state, at this time, multi-way valve three V3, multi-way valve four V4, multi-way valve five V5, multi-way valve six V6, multi-way valve seven V7, multi-way valve nine V9, multi-way valve ten V10 are in the first working state; multi-way valve eight V8 is in the second working state; The carrier gas passes through the gas line five L5 and the multi-way valve eight V8 in the reverse direction through the capture tube two 17, and enters the pre-column two 7 through the multi-way valve seven V7 along the gas line, and then passes through the multi-way valve eight V8 and is separated and purified in the analytical column two 9, and finally carries the target into the detector two 20 for detection.

[0041] Backflush process: switch the flow path to the backflush state. At this time, multi-way valve three V3, multi-way valve eight V8, multi-way valve nine V9, and multi-way valve ten V10 are in the first working state; multi-way valve four V4, multi-way valve five V5, multi-way valve six V6, and multi-way valve seven V7 are in the second working state; At this time, the back-blowing gas passes through the multi-way valve five V5, the multi-way valve six V6, the multi-way valve nine V9, the multi-way valve four V4 from the gas line three L3 in sequence, and then is discharged through the exhaust port; At the same time, backflush 7 passes through the gas line 2 L2 in sequence through the multi-way valve 11 V11, the multi-way valve 12 V12, the multi-way valve 13 V13, the multi-way valve 14 V14, the multi-way valve 3 V3, the multi-way valve 4 V4, the capture pipe 16 and the multi-way valve 5 V5, and then is emptied through the exhaust port; At the same time, the backflush gas passes through the multi-way valve six V6, the multi-way valve seven V7, the capture tube two 17, the multi-way valve eight V8, the pre-column two 7, the multi-way valve seven V7 from the gas line four L4 in sequence, and is then discharged through the exhaust port.

[0042] When the system is in full substance mode, its flow path is roughly consistent with the tracer detection mode. The main difference is that the pre-column 6, analytical column 8 and capture tube 3 18 are not connected to the target material gas path. The gas path between the capture tube 3 18 and the analytical column 8 is maintained by gas path 7 L7. At this time, the pre-column 6 is in a closed state and is not connected to the gas path.

[0043] The present embodiment provides a method for measuring trace substances in environmental water. Under a dual-detector, dual-channel chromatographic column separation system, it is possible to separate and detect targets of different concentrations and different sensitivity levels, so that the detection sensitivity of the target is consistent with its concentration, and the sampling volume does not need to be adjusted. At the same time, it can be adapted to different combinations of packed columns and capillary chromatographic columns to achieve detection of trace halogenated gases over a wide range.

[0044] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A sample pre-concentration and separation system for measuring trace substances in environmental water, characterized in that: include: A gas injection module, which is used to provide standard gas, purge gas and introduce sample source into the system; A sample quantification module, the gas sampling module is connected to the sample quantification module, and the sample quantification module includes a plurality of quantitative loops and a plurality of multi-way valves connected in series, for controlling and adjusting the sample amount; A water sample pretreatment module, the water sample pretreatment module comprising a purge pipe (15), a drying and acid removal pipe 1 (4), a drying and acid removal pipe 2 (5) and a plurality of multi-way valves; A capture and analysis module, wherein the gas sampling module and the water pretreatment module are respectively connected to the capture and analysis module, and the capture and analysis module comprises a front capture tube, a rear capture tube and a plurality of multi-way valves for achieving enrichment, cold focusing and transfer of the target; A separation and detection module, the separation and detection module comprising a pre-column 1 (6), a pre-column 2 (7), an analytical column 1 (8), an analytical column 2 (9), a detector 1 (19), a detector 2 (20) and a plurality of multi-way valves, for achieving separation and detection of a target object.

2. The sample pre-concentration and separation system for measuring trace substances in environmental water according to claim 1, characterized in that: The gas sampling module comprises a nitrogen input pipeline (10), a nitrogen purification pipe (11), a pressure regulator (12) and a multi-way valve 1 (V1); The output end of the pressure regulator (12) is respectively connected to gas circuit 1 (L1), gas circuit 2 (L2), gas circuit 3 (L3), gas circuit 4 (L4) and gas circuit 5 (L5); the gas circuit 1 (L1) is connected to the input end of the multi-way valve 1 (V1), the gas circuit 2 (L2) is connected to the sample quantification module, and the gas circuit 3 (L3), gas circuit 4 (L4) and gas circuit 5 (L5) are respectively connected to the capture and analysis module and / or the separation and detection module; The input end of the multi-way valve 1 (V1) is also connected to an air sample inlet pipeline (13) and a plurality of standard gas inlet pipelines (14); the output end of the multi-way valve 1 (V1) is connected to the sample quantification module.

3. The sample pre-concentration and separation system for measuring trace substances in environmental water according to claim 2, characterized in that: The sample quantification module comprises a multi-way valve eleven (V11), a multi-way valve twelve (V12), a multi-way valve thirteen (V13) and a multi-way valve fourteen (V14) which are connected in series in sequence; The gas circuit 2 (L2) is connected to the multi-way valve 11 (V11), the multi-way valve 12 (V12), the multi-way valve 13 (V13), the multi-way valve 14 (V14) in sequence and finally connected to the water sample pretreatment module; The output end of the multi-way valve 1 (V1) is connected to the multi-way valve 11 (V11), the multi-way valve 12 (V12), the multi-way valve 13 (V13), and the multi-way valve 14 (V14) in sequence and finally connected to the exhaust port.

4. The sample pre-concentration and separation system for measuring trace substances in environmental water according to claim 3, characterized in that: The water sample pretreatment module includes a multi-way valve 2 (V2), a multi-way valve 3 (V3) and a multi-way valve 15 (V15); The multi-way valve 15 (V15) is used to control the water sample to flow into or out of the purge pipe (15); The multi-way valve 2 (V2) is used to balance the air pressure difference in the purge tube (15) during the process of the water sample entering the purge tube (15); The multi-way valve three (V3) is used to switch the purge gas through the purge pipe (15) or bypass.

5. The sample pre-concentration and separation system for measuring trace substances in environmental water according to claim 4, characterized in that: The capture and analysis module includes a multi-way valve four (V4), a multi-way valve five (V5), a multi-way valve six (V6), a multi-way valve seven (V7) and a multi-way valve eight (V8); The front collecting pipe includes a collecting pipe 1 (16), and the rear collecting pipe includes a collecting pipe 2 (17) and a collecting pipe 3 (18); The separation detection module also includes a multi-way valve nine (V9) and a multi-way valve ten (V10); The pre-column one (6) is connected to the system through the multi-way valve nine (V9); the analytical column one (8) and the detector one (19) are connected to the system through the multi-way valve ten (V10); the analytical column two (9) and the detector two (20) are connected to the system through the multi-way valve eight (V8).

6. The sample pre-concentration and separation system for measuring trace substances in environmental water according to claim 5, characterized in that: The multi-way valve six (V6), multi-way valve eight (V8), multi-way valve nine (V9) and multi-way valve ten (V10) are two-position four-way valves, each including a working port a, a working port b, a working port c, a working port d and a first working state and a second working state; When the multi-way valve six (V6) and the multi-way valve eight (V8) are in the first working state, the working port a is connected to the working port b, and the working port c is connected to the working port d; when the multi-way valve six (V6) and the multi-way valve eight (V8) are in the second working state, the working port a is connected to the working port d, and the working port b is connected to the working port c; when the multi-way valve nine (V9) and the multi-way valve ten (V10) are in the first working state, the working port a is connected to the working port d, and the working port b is connected to the working port c; when the multi-way valve nine (V9) and the multi-way valve ten (V10) are in the second working state, the working port a is connected to the working port b, and the working port c is connected to the working port d; The multi-way valve three (V3), multi-way valve four (V4), and multi-way valve five (V5) are two-position six-way valves, each including a working port a, a working port b, a working port c, a working port d, a working port e, a working port f, and a first working state and a second working state; When the multi-way valve three (V3), the multi-way valve four (V4), and the multi-way valve five (V5) are in the first working state, the working port a is connected to the working port b, the working port c is connected to the working port d, and the working port e is connected to the working port f; when the multi-way valve three (V3), the multi-way valve four (V4), and the multi-way valve five (V5) are in the second working state, the working port a is connected to the working port f, the working port b is connected to the working port c, and the working port d is connected to the working port e; The multi-way valve seven (V7) is a two-position eight-way valve, including a working port a, a working port b, a working port c, a working port d, a working port e, a working port f, a working port g and a working port h; when the multi-way valve seven (V7) is in a first working state, the working port a is connected to the working port h, the working port b is connected to the working port c, the working port d is connected to the working port e, and the working port f is connected to the working port g; when the multi-way valve seven (V7) is in a second working state, the working port a is connected to the working port b, the working port c is connected to the working port d, the working port e is connected to the working port f, and the working port g is connected to the working port h; The sample pre-concentration and separation system for measuring trace substances in environmental water includes a tracer detection mode and a full substance mode. When the system is in the tracer detection mode, the flow path is in a first ready state; when the system is in the full substance mode, the flow path is in a second ready state; In the first ready state, multi-way valve three (V3), multi-way valve four (V4), multi-way valve five (V5), multi-way valve seven (V7) and multi-way valve eight (V8) are all in the first working state; multi-way valve six (V6), multi-way valve nine (V9) and multi-way valve ten (V10) are in the second working state; In the second ready state, multi-way valve three (V3), multi-way valve four (V4), multi-way valve five (V5), multi-way valve six (V6), multi-way valve seven (V7), multi-way valve eight (V8), multi-way valve nine (V9), and multi-way valve ten (V10) are all in the first working state.

7. A method for measuring trace substances in environmental water, characterized in that: The sample pre-concentration and separation system according to any one of claims 1 to 6 is used to measure trace substances in water, and when the system is in a tracer detection mode, the following process is included: Water sample purge process: switch the flow path to the water sample purge state, at this time, multi-way valve seven (V7) and multi-way valve eight (V8) are in the first working state; multi-way valve three (V3), multi-way valve four (V4), multi-way valve five (V5), multi-way valve six (V6), multi-way valve nine (V9), and multi-way valve ten (V10) are in the second working state; The purge gas passes through the multi-way valve eleven (V11), the multi-way valve twelve (V12), the multi-way valve thirteen (V13), the multi-way valve fourteen (V14), and the multi-way valve three (V3) from the gas line two (L2) in sequence and then enters the purge pipe (15). After passing through the water sample, the target gas is formed and passes through the multi-way valve two (V2), the drying and acid removal pipe one (4), the multi-way valve three (V3), and the drying and acid removal pipe two (5) in sequence. After the target gas removes the acid gas in the drying and acid removal pipe two (5), it enters the capture pipe one (16) through the multi-way valve four (V4). After the target is captured by the capture pipe one (16), the remaining gas flows out of the capture pipe one (16) and is discharged from the exhaust port after passing through the multi-way valve five (V5). Desorption process: switch the flow path to the desorption state of the collection tube 1 (16), at this time, the multi-way valve 3 (V3), the multi-way valve 4 (V4), the multi-way valve 5 (V5), the multi-way valve 6 (V6), and the multi-way valve 8 (V8) are in the first working state; the multi-way valve 7 (V7), the multi-way valve 9 (V9), and the multi-way valve 10 (V10) are in the second working state; The temperature of the capture tube 1 (16) is increased, and the carrier gas passes through the gas line 4 (L4) in sequence through the multi-way valve 6 (V6), the multi-way valve 5 (V5), the capture tube 1 (16), the multi-way valve 4 (V4), the multi-way valve 9 (V9), the pre-column 1 (6), the multi-way valve 9 (V9), the multi-way valve 6 (V6), the multi-way valve 7 (V7) and the capture tube 2 (17); the target substance is desorbed from the capture tube 1 (16), and pre-separated in the pre-column 1 (6); the target component 1 with a shorter retention time preferentially enters the capture tube 2 (17) and is cold-focused in the capture tube 2 (17), and the remaining gas is discharged through the exhaust port; Injection process: switch the flow path to the injection state, at this time, multi-way valve three (V3), multi-way valve four (V4), multi-way valve five (V5), multi-way valve six (V6), and multi-way valve seven (V7) are in the first working state; multi-way valve eight (V8), multi-way valve nine (V9), and multi-way valve ten (V10) are in the second working state; At this time, the carrier gas from gas line four (L4) passes through multi-way valve six (V6), multi-way valve five (V5), capture tube one (16), multi-way valve four (V4), multi-way valve nine (V9), pre-column one (6), multi-way valve nine (V9), multi-way valve six (V6), multi-way valve seven (V7), multi-way valve ten (V10), capture tube three (18) and analytical column one (8); target component two with a longer retention time flows out of pre-column one (6) at this time, follows the gas line into capture tube three (18) and is cold-focused in capture tube three (18); After the target component 2 is cryofocused in the capture tube 3 (18), the capture tube 3 (18) is heated up, and the target component 2 then enters the analytical column 1 (8) for separation and purification, and finally enters the detector 1 (19) for detection with the target; At the same time, another carrier gas passes through gas line five (L5) through multi-way valve eight (V8) and passes through collecting tube two (17) in the reverse direction, desorbs target component one from collecting tube two (17), and enters pre-column two (7) along the gas line through multi-way valve seven (V7), and then passes through multi-way valve eight (V8) and is separated and purified in analytical column two (9), and finally carries the target into detector two (20) for detection.

8. The method for measuring trace substances in environmental water according to claim 7, characterized in that: When the system is in the tracer detection mode, it also includes a backflush process: the flow path is switched to the backflush state, at which time the multi-way valve three (V3) and the multi-way valve eight (V8) are in the first working state; the multi-way valve four (V4), the multi-way valve five (V5), the multi-way valve six (V6), the multi-way valve seven (V7), the multi-way valve nine (V9), and the multi-way valve ten (V10) are in the second working state; At this time, the backflush gas passes through the multi-way valve five (V5), multi-way valve six (V6), multi-way valve nine (V9), pre-column one (6), multi-way valve nine (V9), multi-way valve four (V4) from the gas line three (L3) in sequence, and then is discharged through the exhaust port; At the same time, backflush seven passes through the gas line two (L2) in sequence through the multi-way valve eleven (V11), the multi-way valve twelve (V12), the multi-way valve thirteen (V13), the multi-way valve fourteen (V14), the multi-way valve three (V3), the multi-way valve four (V4), the capture pipe one (16) and the multi-way valve five (V5), and then is emptied through the exhaust port; At the same time, the backflush gas passes through the gas line four (L4) in sequence through the multi-way valve six (V6), the multi-way valve seven (V7), the capture tube two (17), the multi-way valve eight (V8), the pre-column two (7), the multi-way valve seven (V7), and then is discharged through the exhaust port.

9. The method for measuring trace substances in environmental water according to claim 7, characterized in that: When the system is in full substance mode, it includes the following processes: Water sample purge process: switch the flow path to the water sample purge state, at this time, multi-way valve seven (V7), multi-way valve eight (V8), multi-way valve nine (V9), and multi-way valve ten (V10) are in the first working state; multi-way valve three (V3), multi-way valve four (V4), multi-way valve five (V5), and multi-way valve six (V6) are in the second working state; The purge gas passes through the multi-way valve eleven (V11), the multi-way valve twelve (V12), the multi-way valve thirteen (V13), the multi-way valve fourteen (V14), and the multi-way valve three (V3) from the gas line two (L2) in sequence and then enters the purge pipe (15). After passing through the water sample, the target gas is formed and passes through the multi-way valve two (V2), the drying and acid removal pipe one (4), the multi-way valve three (V3), and the drying and acid removal pipe two (5) in sequence. After the target gas removes the acid gas in the drying and acid removal pipe two (5), it enters the capture pipe one (16) through the multi-way valve four (V4). After the target is captured by the capture pipe one (16), the remaining gas flows out of the capture pipe one (16) and is discharged from the exhaust port after passing through the multi-way valve five (V5). Desorption process: switch the flow path to the desorption state of the collection tube 1 (16), at this time, the multi-way valve 3 (V3), the multi-way valve 4 (V4), the multi-way valve 5 (V5), the multi-way valve 6 (V6), the multi-way valve 8 (V8), the multi-way valve 9 (V9), and the multi-way valve 10 (V10) are in the first working state; the multi-way valve 7 (V7) is in the second working state; The temperature of the trapping tube 1 (16) is increased, and the carrier gas passes through the gas line 4 (L4) in sequence through the multi-way valve 6 (V6), the multi-way valve 5 (V5), the trapping tube 1 (16), the multi-way valve 4 (V4), the multi-way valve 9 (V9), the multi-way valve 6 (V6), the multi-way valve 7 (V7), the trapping tube 2 (17), the multi-way valve 8 (V8), the pre-column 2 (7) and the multi-way valve 7 (V7); the target is desorbed from the trapping tube 1 (16), and pre-separated in the pre-column 2 (7), and the remaining gas passes through the multi-way valve 7 (V7) and is discharged through the exhaust port; Injection process: switch the flow path to the injection state, at this time, multi-way valve three (V3), multi-way valve four (V4), multi-way valve five (V5), multi-way valve six (V6), multi-way valve seven (V7), multi-way valve nine (V9), and multi-way valve ten (V10) are in the first working state; multi-way valve eight (V8) is in the second working state; The carrier gas passes through the gas line five (L5) through the multi-way valve eight (V8) and then passes through the capture tube two (17) in the reverse direction, and enters the pre-column two (7) through the multi-way valve seven (V7) along the gas line, and then passes through the multi-way valve eight (V8) and is separated and purified in the analytical column two (9), and finally carries the target substance into the detector two (20) for detection.

10. The method for measuring trace substances in environmental water according to claim 9, characterized in that: When the system is in full-substance mode, it also includes a backflush process: the flow path is switched to the backflush state, at which time multi-way valve three (V3), multi-way valve eight (V8), multi-way valve nine (V9), and multi-way valve ten (V10) are in the first working state; multi-way valve four (V4), multi-way valve five (V5), multi-way valve six (V6), and multi-way valve seven (V7) are in the second working state; At this time, the back-blowing gas passes through the multi-way valve five (V5), the multi-way valve six (V6), the multi-way valve nine (V9), and the multi-way valve four (V4) from the gas line three (L3), and then is discharged through the exhaust port; At the same time, backflush seven passes through the gas line two (L2) in sequence through the multi-way valve eleven (V11), the multi-way valve twelve (V12), the multi-way valve thirteen (V13), the multi-way valve fourteen (V14), the multi-way valve three (V3), the multi-way valve four (V4), the capture pipe one (16) and the multi-way valve five (V5), and then is emptied through the exhaust port; At the same time, the backflush gas passes through the gas line four (L4) in sequence through the multi-way valve six (V6), the multi-way valve seven (V7), the capture tube two (17), the multi-way valve eight (V8), the pre-column two (7), the multi-way valve seven (V7), and then is discharged through the exhaust port.

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