阅读说明：本技术 一种总有机碳分析仪与稳定同位素质谱联用接口装置 (Total organic carbon analyzer and stable isotope mass spectrometry combined interface device ) 是由 尹希杰 粟蓉 杨海丽 于 2021-07-07 设计创作，主要内容包括：一种总有机碳分析仪与稳定同位素质谱联用接口装置,包括依次设置的二级除水装置、二氧化碳气体净化组件、二氧化碳气体冷冻富集装置、低流速氦气源、色谱柱分离系统；二氧化碳气体冷冻富集装置包括一级不锈钢管冷阱、二级毛细管冷阱和六通阀,一级不锈钢管冷阱用于富集样品气中的CO-(2),二级毛细管冷阱用于浓缩与纯化一级不锈钢管冷阱已富集的CO-(2),一级不锈钢管冷阱的一端连接六通阀的第一阀口,二级毛细管冷阱的两端分别连接六通阀的第二阀口和第五阀口,低流速氦气源连接六通阀的第三阀口,色谱柱分离系统连接六通阀的第四阀口,六通阀的第六阀口为排空阀口,通过六通阀的切换实现CO-(2)的富集、分离及杂质气体的排空。(A total organic carbon analyzer and stable isotope mass spectrometry combined interface device comprises a secondary dewatering device, a carbon dioxide gas purification component, a carbon dioxide gas freezing enrichment device, a low-flow helium source and a chromatographic column separation system which are sequentially arranged; the carbon dioxide gas freezing and enriching device comprises a first-stage stainless steel tube cold trap, a second-stage capillary cold trap and a six-way valve, wherein the first-stage stainless steel tube cold trap is used for enriching CO in the sample gas 2 For secondary capillary cold trapsCO enriched in the first-stage stainless steel tube cold trap of concentration and purification 2 One end of the first-stage stainless steel pipe cold trap is connected with a first valve port of the six-way valve, two ends of the second-stage capillary cold trap are respectively connected with a second valve port and a fifth valve port of the six-way valve, the low-flow-rate helium source is connected with a third valve port of the six-way valve, the chromatographic column separation system is connected with a fourth valve port of the six-way valve, the sixth valve port of the six-way valve is an emptying valve port, and CO is switched through the six-way valve 2 The enrichment and separation of the impurity gases and the evacuation of the impurity gases.)

1. The utility model provides a total organic carbon analysis appearance and stable isotope mass spectrum allies oneself with interface arrangement which characterized in that: the device comprises a secondary dewatering device, a carbon dioxide gas purification component, a carbon dioxide gas freezing and enriching device, a low-flow-rate helium source and a chromatographic column separation system which are sequentially arranged; the carbon dioxide gas freezing and enriching device comprises two-stage liquid nitrogen cold traps and a six-way valve, wherein the two-stage liquid nitrogen cold traps comprise a first-stage stainless steel tube cold trap and a second-stage capillary tube cold trap, and the first-stage stainless steel tube cold trap is used for enriching CO in sample gas₂The second-stage capillary cold trap is used for further concentrating and purifying the enriched CO in the first-stage stainless steel tube cold trap₂One end of the primary stainless steel pipe cold trap is connected with a first valve port of the six-way valve, two ends of the secondary capillary cold trap are respectively connected with a second valve port and a fifth valve port of the six-way valve, the low-flow-rate helium source is connected with a third valve port of the six-way valve, the chromatographic column separation system is connected with a fourth valve port of the six-way valve, the sixth valve port of the six-way valve is an emptying valve port, and CO is switched through the six-way valve₂The enrichment and separation of the impurity gases and the evacuation of the impurity gases.

2. The total organic carbon analyzer and stable isotope mass spectrometry combination interface device of claim 1, wherein: the second-stage water removal device comprises a semiconductor refrigerator, a drain valve and a chemical trap water removal pipe; wherein, gas is rapidly condensed by the semiconductor refrigerator, condensed water is discharged by the drain valve, and the dried gas enters the chemical trap water removal pipe.

3. The total organic carbon analyzer and stable isotope mass spectrometry combination interface device of claim 2, wherein: magnesium perchlorate particles are filled in the chemical trap water removal pipe to adsorb residual moisture in gas.

4. The total organic carbon analyzer and stable isotope mass spectrometry combination interface device of claim 1, wherein: the carbon dioxide gas purification assembly comprises a gas purification pipe and a Naflon moisture separation pipe; wherein, the gas enters a Naflon moisture separation tube after being purified by a gas purification tube and is dried.

5. The total organic carbon analyzer and stable isotope mass spectrometry combination interface device of claim 4, wherein: silver-plated cobalt oxide particles and silver wires are filled in the gas purification tube and are used for adsorbing volatile halogen, purifying gas and preventing the halogen from corroding the instrument.

6. The total organic carbon analyzer and stable isotope mass spectrometry combination interface device of claim 1, wherein: three nickel wires with the same length and the diameter of 0.20-0.30 mm are arranged in the stainless steel pipe of the primary stainless steel pipe cold trap, and the three nickel wires are in a twist shape.

7. The total organic carbon analyzer and stable isotope mass spectrometry combination interface device of claim 1, wherein: the secondary capillary cold trap comprises a quartz capillary tube and a stainless steel tube protective sleeve, and the quartz capillary tube is embedded into the stainless steel tube protective sleeve.

8. The interface device for use of a total organic carbon analyzer in combination with stable isotope mass spectrometry of claim 7, wherein: the quartz capillary tube has an outer diameter of 0.45mm, an inner diameter of 0.32mm and a length of 2 m.

9. The total organic carbon analyzer and stable isotope mass spectrometry combination interface device of claim 1, wherein: the chromatographic column separation system comprises a column incubator, a GC chromatographic column and enriched CO₂And introducing helium gas with low flow rate into a chromatographic column for further separation and purification.

10. A use method of a total organic carbon analyzer and stable isotope mass spectrometry combined interface device is characterized by comprising the following steps:

1) gas is rapidly condensed by a semiconductor refrigerator, condensed water is discharged by a drain valve, then the gas enters a chemical trap water removal pipe to adsorb residual water in the gas, and the dried gas flows through a carbon dioxide gas purification assembly to adsorb volatile halogen and then enters a Naflon water separation pipe to realize the full drying of the gas;

2) before the dried sample gas enters the enrichment system of the carbon dioxide gas freezing and enriching device, a first-stage stainless steel tube cold trap is placed in liquid nitrogen, one end of the first-stage stainless steel tube cold trap is communicated with an emptying valve port of the six-way valve, and CO in the sample gas₂Blowing the mixture into a stainless steel tube by carrier gas with high flow rate, freezing and enriching the mixture, and exhausting and blowing the rest impurity gas along with the carrier gas;

3) before the purging is finished, the second-stage capillary cold trap is immersed in liquid nitrogen in advance, then the six-way valve is switched to connect the first-stage stainless steel tube cold trap and the second-stage capillary cold trap, and the first-stage stainless steel tube cold trap is lifted away from the liquid nitrogen and CO₂Transferring the evaporated gas to a secondary capillary cold trap for freezing and enriching again, wherein the outlet of the secondary capillary cold trap is connected with an emptying valve port of the six-way valve for emptying and purging impurity gas;

4) separating the secondary capillary cold trap from the liquid nitrogen, switching the six-way valve to connect the low-flow helium source, the secondary capillary cold trap and the chromatographic column again, and collecting CO in the capillary₂Vaporizing, sending helium gas with low flow rate into chromatographic column for further separation, and finally introducing into stable isotope mass spectrometer to realize dissolving organic carbon isotope (delta) in water sample¹³C_DOC) The measurement of (1).

Technical Field

The invention relates to the field of organic carbon analysis, in particular to a total organic carbon analyzer and stable isotope mass spectrometry combined interface device.

Background

Dissolved Organic Carbon (DOC) exists in water in various forms, and the matter composition is extremely complex, and mainly comprises mixtures of carbohydrates, amino acids, nitrogen-containing Organic matters, lipids, vitamins, nucleosides, oils, aromatic hydrocarbons, non-aromatic hydrocarbons, macromolecular humic acid and the like in different quantities. The DOC is used as a main energy source and a carbon source of microbial metabolic activity, not only influences the oxidation-reduction process of elements, but also determines the migration and conversion of carbon elements in water to a certain extent, and is an important component of water carbon circulation. Dissolved organic carbon isotope (delta)¹³C_DOC) The source of the DOC in the water body can be identified, the evolution characteristics of the water body environment are indicated, and the DOC biological geochemical process in the water body is researched. But how to test delta efficiently and accurately¹³C_DOCThe value is always one of the difficulties in researching the DOC carbon cycle process.

Currently, for analyzing delta¹³C_DOCThe device mainly comprises a gas sample introduction device (GasBench II) combined stable isotope mass spectrometer (IRMS) and an Element Analyzer (EA) combined stable isotope mass spectrometer. However, these methods have some problems: the GasBench II-IRMS method needs to add different oxidants into a water sample, and oxidize DOC into CO by off-line heating or ultraviolet irradiation and the like₂CO formed₂The carbon isotope composition is tested by GasBench II-IRMS, the pretreatment process of the method is complicated, all volatile organic substances are lost in the reaction process, and finally the deviation of the test result is large. The EA-IRMS method needs long-time freeze-drying treatment on a water sample, has low analysis speed (5-30 samples per week), high background blank and time and labor waste in the conversion process. In recent years, the coupled instrument combines circulating water with an adsorption column to perform CO₂Freeze concentration, attempts to use TOC and IRMS on-line, but the fittings are expensive and require outfittingLarge-scale circulating water machine and expensive CO₂And (4) adsorbing the column. The circulating water machine is externally connected with tap water, the cooling speed is slow, and CO can not be realized₂Rapid freezing of (2); and CO₂After the adsorption column is frozen, the temperature is required to be heated to 230 ℃ to finish CO₂Is released by desorption, ultimately resulting in CO₂The separation and purification process is complex, the test cost is high, the enrichment efficiency is low, and the like.

Disclosure of Invention

The invention aims to solve the technical problems of complicated testing method for the isotope of the dissolved organic carbon in the water body, the combination of a total organic carbon analyzer (TOC) and a stable isotope mass spectrum (IRMS) in the prior art, and CO₂The problems of low separation and purification enrichment efficiency and the like are solved by providing a total organic carbon analyzer and stable isotope mass spectrometry combined interface device

In order to achieve the purpose, the invention adopts the following technical scheme:

a total organic carbon analyzer and stable isotope mass spectrometry combined interface device comprises a secondary dewatering device, a carbon dioxide gas purification component, a carbon dioxide gas freezing enrichment device, a low-flow helium source and a chromatographic column separation system which are sequentially arranged; the carbon dioxide gas freezing and enriching device comprises two-stage liquid nitrogen cold traps and a six-way valve, wherein the two-stage liquid nitrogen cold traps comprise a first-stage stainless steel tube cold trap and a second-stage capillary tube cold trap, and the first-stage stainless steel tube cold trap is used for enriching CO in sample gas₂The second-stage capillary cold trap is used for further concentrating and purifying the enriched CO in the first-stage stainless steel tube cold trap₂One end of the primary stainless steel pipe cold trap is connected with a first valve port of the six-way valve, two ends of the secondary capillary cold trap are respectively connected with a second valve port and a fifth valve port of the six-way valve, the low-flow-rate helium source is connected with a third valve port of the six-way valve, the chromatographic column separation system is connected with a fourth valve port of the six-way valve, the sixth valve port of the six-way valve is an emptying valve port, and CO is switched through the six-way valve₂The enrichment and separation of the impurity gases and the evacuation of the impurity gases.

The second-stage water removal device comprises a semiconductor refrigerator, a drain valve and a chemical trap water removal pipe; wherein, gas is rapidly condensed by the semiconductor refrigerator, condensed water is discharged by the drain valve, and the dried gas enters the chemical trap water removal pipe.

Magnesium perchlorate particles are filled in the chemical trap water removal pipe to adsorb residual moisture in gas.

The carbon dioxide gas purification assembly comprises a gas purification pipe and a Naflon moisture separation pipe; wherein, the gas enters a Naflon moisture separation tube after being purified by a gas purification tube and is dried.

Silver-plated cobalt oxide particles and silver wires are filled in the gas purification tube and are used for adsorbing volatile halogen, purifying gas and preventing the halogen from corroding the instrument.

Three nickel wires with the same length and the diameter of 0.20-0.3 mm are arranged in the stainless steel pipe of the primary stainless steel pipe cold trap, and the three nickel wires are in a twist shape.

The secondary capillary cold trap comprises a quartz capillary tube and a stainless steel tube protective sleeve, and the quartz capillary tube is embedded into the stainless steel tube protective sleeve.

The quartz capillary tube has an outer diameter of 0.45mm, an inner diameter of 0.32mm and a length of 2 m.

The chromatographic column separation system comprises a column incubator, a GC chromatographic column and enriched CO₂And introducing helium gas with low flow rate into a chromatographic column for further separation and purification.

A use method of a total organic carbon analyzer and stable isotope mass spectrometry combined interface device comprises the following steps:

1) gas is rapidly condensed by a semiconductor refrigerator, condensed water is discharged by a drain valve, then the gas enters a chemical trap water removal pipe to adsorb residual water in the gas, and the dried gas flows through a carbon dioxide gas purification assembly to adsorb volatile halogen and then enters a Naflon water separation pipe to realize the full drying of the gas;

2) before the dried sample gas enters the enrichment system of the carbon dioxide gas freezing and enriching device, a first-stage stainless steel tube cold trap is placed in liquid nitrogen, one end of the first-stage stainless steel tube cold trap is communicated with an emptying valve port of the six-way valve, and CO in the sample gas₂Blowing the mixture into a stainless steel tube by carrier gas with high flow rate, freezing and enriching the mixture, and exhausting and blowing the rest impurity gas along with the carrier gas;

3) before the end of purging, second stageImmersing the capillary cold trap in liquid nitrogen in advance, switching the six-way valve to connect the first-stage stainless steel tube cold trap and the second-stage capillary cold trap, and simultaneously lifting the first-stage stainless steel tube cold trap away from the liquid nitrogen and CO₂Transferring the evaporated gas to a secondary capillary cold trap for freezing and enriching again, wherein the outlet of the secondary capillary cold trap is connected with an emptying valve port of the six-way valve for emptying and purging impurity gas;

4) separating the secondary capillary cold trap from the liquid nitrogen, switching the six-way valve to connect the low-flow helium source, the secondary capillary cold trap and the chromatographic column again, and collecting CO in the capillary₂Vaporizing, sending helium gas with low flow rate into chromatographic column for further separation, and finally introducing into stable isotope mass spectrometer to realize dissolving organic carbon isotope (delta) in water sample¹³C_DOC) The measurement of (1).

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

the device can realize online stable online test of TOC and IRMS, does not need to add an oxidant or freeze-drying and other complicated pretreatment operations, and directly oxidizes CO after TOC at high temperature₂Insufflation interface device. In the device, gas passes through a secondary water removal device, a carbon dioxide gas purification assembly, a carbon dioxide gas freezing and enriching device and a chromatographic column separation system in sequence to realize water removal, purification, enrichment and separation of sample gas, and then is introduced into a stable isotope mass spectrometer to realize the dissolution of organic carbon isotopes (delta) in a water sample¹³C_DOC) The measurement of (1). The device has simple accessories, can realize the on-line test of TOC and IRMS only through four separation and purification steps, does not need complicated pretreatment process, has high separation and purification efficiency, easy acquisition and use of accessories and low test cost, and can continuously and stably carry out the dissolution of the organic carbon isotope (delta) in the water sample¹³C_DOC) And (6) testing.

Drawings

FIG. 1 is a schematic diagram of a first-stage stainless steel tube cold trap enrichment flow path;

FIG. 2 is a schematic diagram of a secondary capillary cold trap enrichment flow path;

FIG. 3 is CO₂And (5) sample introduction schematic diagram.

Reference numerals: the device comprises a total organic carbon analyzer (TOC)1, a semiconductor refrigerator 2, a drain valve 3, a chemical trap water removal pipe 4, a gas purification pipe 5, a Naflon moisture separation pipe 6, a primary stainless steel pipe cold trap 7, a nickel wire 8, liquid nitrogen LN 19, a six-way valve 10, a secondary capillary cold trap 11, a quartz capillary 12, liquid nitrogen LN 213, a chromatographic column incubator 14, a separation chromatographic column 15 and a stable isotope mass spectrometer (IRMS) 16.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects of the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

In the invention, after water sample is added with acid to remove dissolved inorganic carbon, the water sample is directly injected into a total organic carbon analyzer (TOC)1 to carry out high-temperature oxidation reaction. Dissolved organic carbon in a water sample is converted into carbon dioxide under the action of oxygen and a Pt catalyst, and the carbon dioxide is blown by helium to enter a combined device of a total organic carbon analyzer (TOC)1 and a stable isotope mass spectrum (IRMS) 16.

As shown in figures 1-3, a total organic carbon analyzer and stable isotope mass spectrometry combined interface device comprises a secondary dewatering device, a carbon dioxide gas purification assembly, a carbon dioxide gas freezing enrichment device, a low-flow helium source and a chromatographic column separation system which are sequentially arranged.

The carbon dioxide gas freezing and enriching device comprises a two-stage liquid nitrogen cold trap and a six-way valve 10, the two-stage liquid nitrogen cold trap comprises a first-stage stainless steel tube cold trap 7 and a second-stage capillary tube cold trap 11, and the first-stage stainless steel tube cold trap 7 is used for enriching CO in sample gas₂The second-stage capillary cold trap 11 is used for further concentrating and purifying the enriched CO in the first-stage stainless steel tube cold trap 7₂One end of the primary stainless steel tube cold trap 7 is connected with a first valve port of the six-way valve 10, two ends of the secondary capillary tube cold trap 11 are respectively connected with a second valve port and a fifth valve port of the six-way valve 10, the low-flow-rate helium source is connected with a third valve port of the six-way valve 10, the chromatographic column separation system is connected with a fourth valve port of the six-way valve 10, the sixth valve port of the six-way valve 10 is an emptying valve port, and CO is realized by switching the six-way valve 10₂The enrichment and separation of the impurity gases and the evacuation of the impurity gases.

In this embodiment, three nickel wires 8 with the same length and a diameter of 0.20-0.30 mm are arranged in the stainless steel tube of the first-stage stainless steel tube cold trap 7, and the three nickel wires are in a twisted shape, specifically, the stainless steel tube has an inner diameter of 0.5mm, an outer diameter of 1.6mm, and a length of about 2 m.

The secondary capillary cold trap 11 comprises a quartz capillary tube 12 and a stainless steel tube protective sleeve, and the quartz capillary tube 12 is embedded into the stainless steel tube protective sleeve; the quartz capillary 12 has an outer diameter of 0.45mm, an inner diameter of 0.32mm and a length of 2 m.

The secondary water removal device is mainly used for removing water in gas flowing out of the total organic carbon analyzer 1, is beneficial to purification and separation of target gas in the next step, and comprises a semiconductor refrigerator 2, a drain valve 3 and a chemical trap water removal pipe 4; the voltage of the semiconductor refrigerator 2 is 12V, the power is 72W, the refrigerating temperature is-4 ℃, gas is rapidly condensed by the semiconductor refrigerator 2, condensed water is discharged by a drain valve 3, and the dried gas enters a chemical trap water removal pipe 4; magnesium perchlorate particles are filled in the chemical trap water removal pipe 4 to adsorb residual moisture in the gas.

The carbon dioxide gas purification assembly comprises a gas purification pipe 5 and a Naflon moisture separation pipe 6; wherein, the gas enters a Naflon moisture separation tube 6 after being purified by a gas purification tube 5 and is dried. Silver-plated cobalt oxide particles and silver wires are filled in the gas purification tube 5 and are used for adsorbing volatile halogen, purifying gas and preventing the halogen from corroding the instrument.

The chromatographic column separation system comprises a column incubator and a GC chromatographic column 15, and enriched CO₂Entering a GC chromatographic column 15 along with low flow rate helium for further separation and purification; the temperature of the column incubator is 70 ℃, and the length of a chromatographic column is 27.5m, and the inner diameter of the chromatographic column is 0.32 mm.

In the invention, gas firstly passes through a semiconductor refrigerator 2 and a chemical trap water removal pipe 4 to remove most of water, then passes through a gas purification assembly to remove volatile halogen, and then passes through a Naflon water separation pipe 6 to further remove residual water. After the sample gas enters an enrichment system, the sample gas firstly passes through a stainless steel tube cold trap 7 filled with a nickel wire 8 along with helium gas with high flow rate, and CO is contained in liquid nitrogen₂Is enriched by freezing. Then the six-way valve 10 is switched to lift the first-stage stainless steel pipe cold trap 7 away from liquid nitrogen and CO₂After vaporization, the mixture is transferred to a secondary capillary cold trap 11 and is enriched and purified again in liquid nitrogen. Finally, helium with low flow rate is sent into a separation chromatographic column 15 for further separation, and then is introduced into a stable isotope mass spectrometer 16, so that organic carbon isotopes (delta) are dissolved in a water sample¹³C_DOC) The measurement of (1).

The specific working process of the invention is as follows:

1. as shown in fig. 1, under the purging of the carrier gas, the gas from the total organic carbon analyzer 1 is first rapidly condensed by the semiconductor refrigerator 2, the refrigerating temperature is-4 ℃, and the condensed water is discharged through the drain valve 3. And then the gas enters a chemical trap water removal pipe 4, magnesium perchlorate particles are filled in the pipe, residual moisture in the gas is adsorbed, and most of moisture in the gas is removed through the above two-stage water removal device. The dried gas flows through the gas purification tube 5, absorbs volatile halogen through the filled silver-plated cobalt oxide and silver wires, purifies the gas and prevents the halogen gas from corroding the instrument, and then enters the Naflon moisture separation tube 6 to realize the full drying of the sample gas.

2. And 5-10 s before the dried gas enters the enrichment system, the primary stainless steel tube cold trap 7 is placed in liquid nitrogen LN 19, and one end of the primary stainless steel tube cold trap is connected with an emptying valve port of the six-way valve 10. CO in the sample₂Blowing into the first-stage stainless steel tube cold trap 7 filled with nickel wires 8 by high-flow helium gas flow (about 30ml/min), and freezing for 300s (according to CO)₂The concentration of (c) may adjust the purge time), the remaining impurity gas is evacuated with the carrier gas.

3. 5-10 s before the purging is finished, as shown in fig. 2, the quartz capillary tube 12 is immersed in liquid nitrogen LN 213 in advance, and then the six-way valve 10 is switched to connect the primary stainless steel tube cold trap 7 and the quartz capillary tube 12. Simultaneously, the first-stage stainless steel pipe cold trap 7 is lifted away from liquid nitrogen LN 19, CO₂Transferring the evaporated gas to a quartz capillary tube 12 for freezing again, wherein the freezing enrichment time is 95s, and the outlet of the quartz capillary tube 12 is connected with an emptying valve port of the six-way valve 10 for emptying and purging the impurity gas.

4. Referring to FIG. 3, the quartz capillary 12 is lifted away from the liquid nitrogen, the six-way valve 10 is again switched to connect the low flow rate helium source, the secondary capillary cold trap 11 and the GC chromatographic column 15, and the CO in the quartz capillary 12₂Vaporization ofSending helium gas (about 1.5ml/min) with low flow rate into a GC chromatographic column 15 for further separation and purification, stabilizing the temperature of a chromatographic column incubator 14 at 70 ℃, and finally introducing a stable isotope mass spectrometer 16 to realize the dissolution of the organic carbon isotope (delta) in a water sample¹³C_DOC) The measurement of (1).