Quantitative loop sampling device and volatile organic compound detection equipment

Abstract

The utility model relates to a quantitative loop sample introduction device and volatile organic compound detection equipment, and relates to the volatile organic compound detection technology, the quantitative loop sample introduction device comprises a quantitative loop, the gas inlet end of the quantitative loop is connected with a second interface of a six-way switching valve, and the gas outlet end of the quantitative loop is connected with a fifth interface of the six-way switching valve; the emptying electromagnetic valves are arranged at preset positions of the quantitative ring; a first interface of the six-way switching valve is used for connecting the sample inlet, a sixth interface of the six-way switching valve is used for connecting the sample outlet, a third interface of the six-way switching valve is used for connecting the carrier gas inlet, and a fourth interface of the six-way switching valve is used for connecting the carrier gas outlet. According to the technical scheme provided by the embodiment of the utility model, on the premise of realizing large-volume sample introduction, the sample introduction volume can be automatically changed according to use requirements, the volume metering is accurate, and the repeatability is good.

Description

Technical Field

[0001] The utility model relates to the technical field of volatile organic compound detection, in particular to a quantitative loop injection device and a volatile organic compound detection device. Background Art

[0002] For the detection of volatile organic compounds, the gas sample to be measured needs to be input into the detection device.

[0003] The existing injection method can adopt quantitative loop injection, as Figure 1-2 shown. Quantitative loop injection is to introduce the gas sample into the quantitative loop through gas pressure difference. After the gas sample enters the quantitative loop, the gas volume inside the quantitative loop is determined through pressure balance. Under the condition of the same pressure, the volume inside the quantitative loop is a fixed value. The advantage of quantitative loop injection is accurate volume measurement. The advantage of a small quantitative loop is that small-volume quantification can be carried out to avoid contaminating the analysis system with high-concentration samples; the advantage of a large quantitative loop is that the method detection limit can be reduced.

[0004] However, the volume of the quantitative loop is fixed. If a large-volume sample needs to be detected, the volume of the selected quantitative loop needs to be large enough. Since the volume of the quantitative loop cannot be automatically changed, the injection volume is the volume of the quantitative loop. When the sample volume changes, to change the injection volume, only the quantitative loop can be manually replaced, which makes the detection work more complicated and affects the detection efficiency. Summary of the Utility Model

[0005] The purpose of the utility model is to provide a quantitative loop injection device and a volatile organic compound detection device, so that the injection volume can be changed according to the use requirements when quantitative loop injection is adopted.

[0006] To achieve the above purpose, an embodiment of the utility model provides a quantitative loop injection device, including a quantitative loop, whose intake end is connected to the second interface of a six-way switching valve, and whose outlet end is connected to the fifth interface of the six-way switching valve; a plurality of vent solenoid valves, arranged at preset positions of the quantitative loop; the six-way switching valve, whose first interface is used to connect to a sample inlet, whose sixth interface is used to connect to a sample outlet, whose third interface is used to connect to a carrier gas inlet, and whose fourth interface is used to connect to a carrier gas outlet.

[0007] Optionally, the plurality of vent solenoid valves are equally or unequally spaced on the quantitative loop.

[0008] Optionally, the number of the vent solenoid valves is 4-6.

[0009] Optionally, the quantitative loop injection device further includes a carrier gas inlet pipeline, connecting the third interface of the six-way switching valve; a carrier gas outlet pipeline, connecting the fourth interface of the six-way switching valve.

[0010] Optionally, the fixed-volume loop injection device further includes a focusing trap, a three-way connector, and a split solenoid valve. The first end of the focusing trap is connected to the outlet end of the carrier gas outlet pipeline, the other end of the focusing trap is connected to the first end of the three-way connector, one end of the split solenoid valve is connected to the second end of the three-way connector, and the third end of the three-way connector is used for connecting a detection instrument.

[0011] Optionally, the fixed-volume loop injection device further includes a flow rate regulating device, which is connected to the other end of the split solenoid valve.

[0012] Optionally, the fixed-volume loop injection device further includes a sample inlet pipeline, which is connected to the first interface of the six-way switching valve; and a sample outlet pipeline, which is connected to the sixth interface of the six-way switching valve.

[0013] Optionally, the fixed-volume loop injection device further includes a switching valve, which is arranged on the sample outlet pipeline.

[0014] An embodiment of the present invention further provides a volatile organic compound detection device, which includes the fixed-volume loop injection device provided by any embodiment of the present invention, and further includes a detection instrument, which is connected to the gas outlet end of the fixed-volume loop injection device.

[0015] Optionally, the detection instrument includes a chromatograph.

[0016] As can be seen from the above, the technical solution provided by the embodiment of the present invention has a simple structure, accurate volume measurement, good repeatability through the fixed-volume loop injection method. By changing the position of the fixed-volume loop discharge port, the injection volume can be changed, and the volume can be changed according to the use requirements, which is more efficient when detecting different sample volumes. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic structural diagram of a fixed-volume loop injection device in the sample filling state in the prior art;

[0018] Figure 2 is a schematic structural diagram of a fixed-volume loop injection device in the sample output state in the prior art;

[0019] Figure 3 is a schematic structural diagram of one of the usage states of the fixed-volume loop injection device provided by the embodiment of the present invention;

[0020] Figure 4 is a schematic structural diagram of another usage state of the fixed-volume loop injection device provided by the embodiment of the present invention;

[0021] Figure 5 is a schematic structural diagram of the fixed-volume loop provided by the embodiment of the present invention. DETAILED DESCRIPTION

[0022] The technical solution of the present utility model will be further described below in conjunction with the accompanying drawings and through specific embodiments. It can be understood that the specific embodiments described herein are only used to explain the present utility model, rather than limiting the present utility model. Additionally, it should be noted that for the convenience of description, only the parts related to the present utility model are shown in the drawings, rather than all of them.

[0023] In the description of the embodiments of the present utility model, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0024] This embodiment provides a quantitative loop injection device, as Figure 3-4 , including a quantitative loop 1, whose gas inlet end is connected to the second interface 22 of the six-way switching valve 2, and whose gas outlet end is connected to the fifth interface 25 of the six-way switching valve 2; a plurality of vent solenoid valves 11, arranged at preset positions of the quantitative loop 1; the six-way switching valve 2, whose first interface 21 is used to connect to the sample inlet, whose sixth interface 26 is used to connect to the sample outlet, whose third interface 23 is used to connect to the carrier gas inlet, and whose fourth interface 224 is used to connect to the carrier gas outlet. Among them, in the above implementation, the volume of the quantitative loop is variable and can combine the injection advantages of a large quantitative loop and a small quantitative loop, improving the applicability of the method. It can not only reduce the method detection limit but also avoid system contamination. The quantitative loop injection device of this embodiment has a simple structure, good stability, low failure rate, accurate volume measurement using the quantitative loop, good repeatability, can perform full sample analysis, and the volume can be automatically changed according to the usage requirements.

[0025] Optionally, the plurality of vent solenoid valves 11 are evenly or unevenly distributed on the quantitative loop 1. Exemplarily, as Figure 5 there are 4 vent solenoid valves distributed on the quantitative loop. The distribution of vent solenoid valves 1-4 can be equidistant, that is, dividing the quantitative loop into equal volumes, or uneven, that is, dividing the quantitative loop into unequal volumes. The number and distribution positions of the vent solenoid valves can be selected and set according to the total volume of the quantitative loop and the injection volume that may be used during sample detection. The connecting pipelines of the vent solenoid valves of the quantitative loop use thinner pipelines (for example, 1 / 16 inch) to reduce the dead volume.

[0026] Optionally, the number of the vent solenoid valves is 4-6.

[0027] Optionally, the quantitative loop injection device further includes a carrier gas inlet pipeline 31 connected to the third interface 23 of the six-way switching valve 2; and a carrier gas outlet pipeline 32 connected to the fourth interface 24 of the six-way switching valve 2.

[0028] Optionally, the quantitative loop injection device further includes a focusing trap 41, a three-way connector 42, and a split solenoid valve 43. The first end of the focusing trap 41 is connected to the outlet end of the carrier gas outlet pipeline 32, the other end of the focusing trap 41 is connected to the first end of the three-way connector 42, one end of the split solenoid valve 43 is connected to the second end of the three-way connector 42, and the third end of the three-way connector 42 is used to connect to the detection instrument. Among them, in the implementation method using a focusing trap, when the volume of the quantitative loop is large, the large quantitative loop has disadvantages. Excessive gas injection volume will cause the sample in the quantitative loop to not be quickly transferred to the analysis system (for example, the main flow rate acceptable by the gas chromatography-mass spectrometry analysis system is 0.5 - 2 ml / min. If the volume of the quantitative loop is too large, the transfer time will be too long), resulting in a poor chromatographic peak shape. However, the focusing trap can make up for this problem. The sample is first transferred from the quantitative loop to the focusing trap. The focusing trap adsorbs the analyte through low temperature or an adsorbent, and then the focusing trap is heated to achieve sample injection. The volume of the focusing trap is much smaller than that of the quantitative loop, so the sample can be transferred through a small flow rate. The method of transferring a large flow rate to the focusing trap ensures the sharpness of the peak shape and improves the transfer efficiency. In the case of large-volume injection, it can ensure instantaneous injection, with sharp chromatographic peaks and good resolution. The focusing trap can select a thinner pipeline (for example, 1 / 32 inch) to improve the sharpness of the peak, and the filler can be added or not according to requirements.

[0029] Optionally, the quantitative loop injection device further includes a flow regulating device connected to the other end of the split solenoid valve.

[0030] Optionally, the quantitative loop injection device further includes a sample inlet pipeline 51 connected to the first interface 21 of the six-way switching valve 2; and a sample outlet pipeline 52 connected to the sixth interface 26 of the six-way switching valve 2.

[0031] Optionally, the quantitative loop injection device further includes a switching valve 6 provided on the sample outlet pipeline 52.

[0032] During the use of the quantitative loop injection device, when filling the sample, the six-way switching valve 2 rotates Figure 3 to a position where the high-pressure sample enters the quantitative loop (the filling volume is determined according to requirements. When a small-volume injection is required, the evacuation solenoid valve 1 shown in Figure 5 is opened, and the other evacuation solenoid valves are closed. When the injection volume needs to be increased, and so on. When all the evacuation solenoid valves are opened, it is the maximum injection volume); when focusing the sample (when a small-volume injection is selected for the quantitative loop, the focusing function may not be used), the focusing trap 41 cools down, and the six-way switching valve 2 rotates toFigure 4 At this position, the shunt solenoid valve 43 is opened, and the carrier gas carries the sample inside the sampling loop 1 into the focusing trap 41. There are two flow paths for the carrier gas passing through the focusing trap 41. One part enters the chromatographic column, and the other part is exhausted through the shunt solenoid valve 43. A flow rate regulating device is connected to the rear end of the shunt solenoid valve 43, and the shunt flow rate can be adjusted according to the analysis requirements. When injecting the sample, the six-port switching valve 2 rotates to Figure 3 this position, and the focusing trap 41 is heated for sample injection.

[0033] An embodiment of the present invention further provides a volatile organic compound detection device, which includes the sampling loop injection device provided in any embodiment of the present invention, and further includes a detection instrument connected to the gas outlet end of the sampling loop injection device.

[0034] Optionally, the detection instrument includes a chromatograph.

[0035] Although the present invention has been described in detail above with general descriptions, specific embodiments and experiments, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. A quantitative loop injection device, characterized in that: It includes a quantitative ring, whose air inlet end is connected to the second interface of the six-way switching valve, and whose air outlet end is connected to the fifth interface of the six-way switching valve; a plurality of exhaust solenoid valves are arranged at preset positions of the quantitative ring; the six-way switching valve, whose first interface is used to connect to the sample inlet, whose sixth interface is used to connect to the sample outlet, whose third interface is used to connect to the carrier gas inlet, and whose fourth interface is used to connect to the carrier gas outlet.

2. The quantitative loop injection device according to claim 1, characterized in that: The plurality of exhaust solenoid valves are distributed on the quantitative ring at equal distances or at unequal distances.

3. The quantitative loop injection device according to claim 2, characterized in that: The number of the exhaust solenoid valves is 4-6.

4. The quantitative loop injection device according to claim 1, characterized in that: It also includes a carrier gas inlet pipeline connected to the third interface of the six-way switching valve; and a carrier gas outlet pipeline connected to the fourth interface of the six-way switching valve.

5. The quantitative loop injection device according to claim 4, characterized in that: It also includes a focusing trap, a three-way connector and a diverter solenoid valve, wherein the first end of the focusing trap is connected to the outlet end of the carrier gas outlet pipeline, the other end of the focusing trap is connected to the first end of the three-way connector, one end of the diverter solenoid valve is connected to the second end of the three-way connector, and the third end of the three-way connector is used to connect a detection instrument.

6. The quantitative loop injection device according to claim 5, characterized in that: It also includes a flow regulating device connected to the other end of the diversion solenoid valve.

7. The quantitative loop injection device according to claim 1, characterized in that: It also includes a sample air inlet pipeline connected to the first interface of the six-way switching valve; and a sample air outlet pipeline connected to the sixth interface of the six-way switching valve.

8. The quantitative loop injection device according to claim 7, characterized in that: It also includes a switch valve, which is arranged on the sample outlet pipeline.

9. A volatile organic compound detection device, characterized in that: It comprises the quantitative loop injection device according to any one of claims 1 to 8, and also comprises a detection instrument connected to the gas outlet end of the quantitative loop injection device.

10. The volatile organic compound detection device according to claim 9, characterized in that: The detection instrument comprises a chromatograph.

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