Gas phase carbon center free radical in-situ capture method based on micro-fluidic chip technology

Abstract

The invention discloses a gas phase carbon center free radical in-situ capture method based on a micro-fluidic chip technology, and belongs to the technical field of micro-fluidic chip analysis and testing. The winding array micro-channel structure is formed by etching on the quartz substrate and comprises a sample introduction channel, a gas phase carbon center free radical in-situ capture channel (winding array micro-channel) and a collection channel, and the sample introduction channel and the collection channel are both connected with the quartz capillary tube. The sample introduction channel is used for inputting gas; the gas-phase carbon center free radical in-situ capturing channel is used for coating a capturing agent and capturing gas-phase carbon center free radicals; and the collection channel is used for collecting samples. The quartz micro-fluidic chip with the gas-phase carbon center free radical in-situ capture channel has a longer channel and a larger inner surface area of the channel, so that the quartz micro-fluidic chip can be coated with more capture agents, and the capture efficiency is remarkably improved. And a 2, 2, 6, 6-tetramethylpiperidine oxide trapping agent is adopted. According to the invention, in-situ capture and efficient enrichment of trace gas-phase carbon center free radicals can be realized.

Description

Technical Field

[0001] The invention belongs to the technical field of microfluidic chip analysis and testing, and particularly relates to an in-situ capture method for gas-phase carbon center free radicals based on microfluidic chip technology. Background Art

[0002] Understanding and monitoring the transformation of gas-phase free radicals is essential for understanding atmospheric chemical phenomena. Gas-phase carbon-centered free radicals from parent pollutants play an important role in the oxidation of volatile organic compounds (VOCs). As important intermediates, these free radicals carry valuable molecular structural information about pollutants. Understanding their formation and behavior is crucial for understanding the degradation mechanism of pollutants. The initial formation of gas-phase carbon-centered free radicals can be triggered by a variety of processes, such as photolysis, hydrogen abstraction, or addition reactions. As organic pollutants are transformed and degraded, gas-phase carbon-centered free radicals from parent pollutants will initiate chain reactions, including rearrangement and subsequent oxidation. Identifying and characterizing these gas-phase carbon-centered free radical intermediates can provide deep insights into the interactions between organic pollutants and oxidative free radical species.

[0003] Gas-phase carbon-centered free radicals are highly reactive species with the amazing ability to undergo transformations in microseconds or even shorter times. This rapidity makes it extremely challenging to capture and study their transient existence. Due to the short lifetime and extremely low concentration of gas-phase carbon-centered free radicals, it is particularly important to improve the sensitivity of analytical methods. An effective strategy to address this problem is sample enrichment and concentration. However, traditional off-line enrichment methods (such as solid phase extraction or liquid phase extraction) often face defects such as limited enrichment capacity, loss of target substances, and excessive eluent volume requirements. Piperidine nitrogen oxides show extremely high reactivity to carbon-centered free radicals (10 8 -10 9 M -1 s -1 ), is commonly used to capture gas-phase carbon-centered free radicals by cross-coupling. The formed alkoxyamine adducts can then be studied using common characterization techniques, including electron paramagnetic resonance (EPR), mass spectrometry (MS), fluorescence detection, and electrochemical detection. However, this approach is generally applicable to liquid-phase free radicals. In the process of capturing gas-phase free radicals, it is often necessary to transfer the gaseous sample to a liquid medium for capture and subsequent analysis, which inevitably introduces interference from the liquid environment, resulting in inaccurate analysis results.

[0004] Therefore, it is necessary to study a method based on microfluidic chip technology with strong enrichment ability, high capture efficiency, exclusion of other environmental interferences, and realization of in situ capture of gas-phase carbon center free radicals. Summary of the invention

[0005] In order to solve the problems existing in the prior art for capturing gas-phase carbon-centered free radicals, the present invention proposes an in-situ capture method for gas-phase carbon-centered free radicals based on microfluidic chip technology, which can achieve in-situ capture and efficient enrichment of gas-phase carbon-centered free radicals.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for in-situ capturing of gas-phase carbon center free radicals based on microfluidic chip technology, wherein the captured agent used is TEMPO having a structure shown in formula (1):

[0008]

[0009] The equipment used includes an injection channel, an in-situ capture channel for gas-phase carbon center free radicals, and a collection channel; the injection channel, the in-situ capture channel for gas-phase carbon center free radicals, and the collection channel are connected together in sequence; the injection channel and / or the in-situ capture channel for gas-phase carbon center free radicals are equipped with a temperature control module or device for controlling the temperature of the injection channel and / or the in-situ capture channel for gas-phase carbon center free radicals; the in-situ capture channel for gas-phase carbon center free radicals is a winding channel array.

[0010] The injection channel is used to input samples that generate gas-phase carbon center free radicals. The gas-phase carbon center free radical in-situ capture channel is coated with a capture agent for free radical capture. The collection channel is used to collect and capture carbon center free radical products.

[0011] The equipment used is as follows: the channel is etched on the surface of the chip substrate, including an injection channel, an in-situ capture channel for gas-phase carbon center free radicals, and a collection channel. The two chip substrates are buckled up and down so that the channels form a cavity channel. The injection channel is connected to an external quartz capillary for pumping in or blowing in samples that generate gas-phase carbon center free radicals. The collection channel is connected to an external quartz capillary for pumping out or blowing out related captured carbon center free radical products (liquid or gas).

[0012] The chip substrate is made of quartz material, the channel in the chip substrate is made by wet etching, and the two chip substrates are bonded together by a thermal bonding method.

[0013] Preferably, the channel cross section of the injection channel is circular, with a diameter of 360 to 500 μm.

[0014] Preferably, the channel cross-section of the gas-phase carbon-centered free radical in-situ capture channel is circular, with a diameter of 80 to 120 μm.

[0015] Preferably, the collection channel has a circular cross section with a diameter of 360 to 500 μm.

[0016] A method for in-situ capture of gas-phase carbon center free radicals based on microfluidic chip technology comprises the following steps:

[0017] The sample generating gas phase carbon center free radicals, such as acetone, is placed in a volatile organic matter container connected to the sampling channel; a free radical capture reagent is placed in the gas phase carbon center free radical in-situ capture channel, and the temperature of the temperature control module is controlled to a predetermined temperature (the temperature is the temperature for generating gas phase carbon center free radicals);

[0018] By controlling the temperature of a constant temperature control module, a sample such as acetone that generates gaseous carbon center free radicals is volatilized into gas, and a carrier gas is used to make the sample such as acetone that generates gaseous carbon center free radicals flow into a microfluidic chip, thereby forming gaseous carbon center free radicals in the microfluidic chip, and finally being captured by a free radical capture agent in the microfluidic chip; the microfluidic chip is eluted with mass spectrometry grade methanol, and the sample (eluted liquid) is collected for mass spectrometry detection.

[0019] When the free radical capture reagent is placed in the gas-phase carbon-centered free radical in situ capture channel, the free radical capture agent TEMPO is dissolved in methanol (concentration range is 10 μM to 1 mM) and then flows through the gas-phase carbon-centered free radical in situ capture channel, so that the capture agent TEMPO is coated on the inner surface of the gas-phase carbon-centered free radical in situ capture channel.

[0020] Beneficial effects: The in-situ capture method of gas-phase carbon center free radicals based on microfluidic chip technology produced by the present invention has a better performance advantage in the capture process of trace gas-phase carbon center free radicals. It solves the problem of limited capture and enrichment efficiency of gas-phase carbon center free radicals in traditional gas-phase carbon center free radical in-situ capture methods. The present invention can quickly and timely capture gas-phase carbon center free radicals. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the structure of a microfluidic quartz chip for in-situ capture of gas-phase carbon-centered free radicals

[0022] Figure 2 Capturing the mass spectra of gas-phase carbon-centered free radicals produced by acetone photodegradation

[0023] Figure 3 Schematic diagram of the overall device of the embodiment. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with specific examples. Detailed implementation methods and specific operation processes are given, and the examples will help to understand the present invention, but the protection scope of the present invention is not limited to the following examples.

[0025] Example 1

[0026] Design and construct a microfluidic chip, and prepare the quartz microfluidic chip used in the present invention by standard photolithography and wet etching technology, combined with plasma assisted bonding technology. The specific steps are as follows: fix a quartz chrome plate coated with a 500nm thick AZ-1500 type positive photoresist and a 100nm thick chromium layer in a high-resolution contact exposure machine, adjust the position of the film mask, align it with the quartz chrome plate, and then expose it by ultraviolet light to transfer the designed mask pattern to the quartz chrome plate. Etch the microchannel required for this experiment uniformly on the quartz chrome plate through development, chrome removal, wet etching and other operations.

[0027] Prepare a certain amount of free radical scavenger TEMPO, pump the free radical scavenger into the microfluidic chip through a syringe pump, pump the free radical scavenger at a flow rate of 1-100 μL / min for the first 5-10 minutes, and then let it stand for 20-25 minutes.

[0028] Prepare 100 μL of acetone (exhaust oxygen in advance) and put it into a volatile organic compound container. Insert the quartz capillary at the end of the gas flow control module and the quartz capillary outside the microfluidic chip into a volatile organic compound container (note that the quartz capillaries must be above the liquid level). Put the volatile organic compound container into the constant temperature water bath of the constant temperature control module and control the temperature at 60-80°C.

[0029] At this time, the microfluidic chip was placed under a mercury lamp to react for 10-15 minutes, and the quartz capillary exposed to the air was sealed with a silicone sheet to form a closed reaction space.

[0030] Finally, the microfluidic chip was eluted with mass spectrometry grade methanol and pumped in with a syringe pump at a flow rate of 100 μL / min for a total of 90 seconds. The microfluidic chip was then sonicated for 7-10 seconds, and the residual liquid was blown out with a nitrogen bottle. All the liquid was collected and detected by electrospray high-resolution mass spectrometry. The mass spectrum characterization results are shown in the attached Figure 2 .

[0031] The overall device schematic diagram of the above embodiment is attached. Figure 3 .

[0032] The present invention designs a microfluidic chip with a meandering array channel structure, which can have better performance advantages in the process of capturing trace gas-phase carbon-centered free radicals, and effectively solves the problem of limited capture and enrichment efficiency of gas-phase carbon-centered free radicals in traditional in-situ capture methods of gas-phase carbon-centered free radicals.

[0033] The present invention provides a method and idea for in-situ capture of gas-phase carbon center free radicals based on microfluidic chip technology. There are many methods and approaches to implement the technical solution. The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention. All components not specified in this embodiment can be implemented by existing technologies.

Claims

1. A method for in-situ capture of gas-phase carbon center free radicals based on microfluidic chip technology, characterized in that: The capture agent used is TEMPO, which has the structure shown in formula (1): The equipment used includes an injection channel, an in-situ capture channel for gas-phase carbon center free radicals, and a collection channel; the injection channel, the in-situ capture channel for gas-phase carbon center free radicals, and the collection channel are connected together in sequence; the injection channel is used to input samples that generate gas-phase carbon center free radicals, and the in-situ capture channel for gas-phase carbon center free radicals is coated with a capture agent for free radical capture; the collection channel is used to collect and capture carbon center free radical products; the in-situ capture channel for gas-phase carbon center free radicals is a winding channel array.

2. The method according to claim 1, characterized in that The injection channel and / or the gas phase carbon center free radical in-situ capture channel are equipped with a temperature control module or device for controlling the temperature of the injection channel and / or the gas phase carbon center free radical in-situ capture channel.

3. The method according to claim 1, characterized in that The equipment used is: the channel is etched on the surface of the chip substrate, including an injection channel, a gas-phase carbon center free radical in-situ capture channel, and a collection channel. Two chip substrates are buckled up and down so that the channels form a cavity channel. The injection channel is connected to an external quartz capillary for pumping in or blowing in samples that generate gas-phase carbon center free radicals, and the collection channel is connected to an external quartz capillary for pumping out or blowing out related captured carbon center free radical products (liquid or gas); The chip substrate is made of quartz material, the channel in the chip substrate is made by wet etching, and the two chip substrates are bonded together by a thermal bonding method.

4. The method according to claim 1, characterized in that The channel cross section of the injection channel is circular, and the diameter is 360-500 μm.

5. The method according to claim 1, characterized in that The channel cross section of the gas phase carbon center free radical in-situ capture channel is circular, and the diameter is 80-120 μm.

6. The method according to claim 1, characterized in that The channel cross section of the collecting channel is circular, and the diameter is between 360 and 500 μm.

7. The method according to claim 1, characterized in that The steps include: The sample generating gas phase carbon center free radicals, such as acetone, is placed in a volatile organic matter container connected to the injection channel; a free radical capture reagent is placed in the gas phase carbon center free radical in-situ capture channel, and the temperature of the temperature control module is controlled to a predetermined temperature; By controlling the temperature of a constant temperature control module, a sample such as acetone that generates gaseous carbon center free radicals is volatilized into gas, and a carrier gas is used to make the sample such as acetone that generates gaseous carbon center free radicals flow into a microfluidic chip, thereby forming gaseous carbon center free radicals in the microfluidic chip, and finally being captured by a free radical capture agent in the microfluidic chip; the microfluidic chip is eluted with mass spectrometry grade methanol, and samples are collected and detected by mass spectrometry.

8. The method according to claim 1, characterized in that When the free radical capture reagent is placed in the gas-phase carbon-centered free radical in situ capture channel, the free radical capture agent TEMPO is dissolved in methanol (concentration range is 10 μM to 1 mM) and then flows through the gas-phase carbon-centered free radical in situ capture channel, so that the capture agent TEMPO is coated on the inner surface of the gas-phase carbon-centered free radical in situ capture channel.

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