CN105223263B - A kind of detection platform and detection method for being used to measure trace element in biological sample - Google Patents

Abstract

The present invention relates to a kind of detection platform and detection method for being used to measure trace element in biological sample, the detection platform includes：By the Frozen Biological to solid refrigeration system；The laser ablation system of laser ablation is carried out to being refrigerated to solid biological sample；And the aerosol of the biological sample for laser ablation to be obtained is loaded into ionization in plasma and detects the inductivity coupled plasma mass spectrometry system of the Determination of trace element contents in the biological sample.

Description

A detection platform and detection method for determining trace elements in biological samples

technical field

The invention belongs to the field of element detection of biological materials, and in particular relates to a detection platform and a detection method suitable for measuring trace elements in biological samples by using LA-ICP-MS method.

Background technique

Inductively coupled plasma mass spectrometry (ICP-MS) has been around for 25 years. Over two decades, it has rapidly developed into a widely used and highly regarded analytical technique. Thousands of ICP-MS have been used as routine analysis methods around the world, equipped in laboratories in different research fields. With the development and improvement of the instrument itself, it has shown its unique ability in the analysis of trace and ultra-trace elements.

The traditional method of analyzing trace elements in biological samples adopts classical wet digestion, microwave digestion, or high-pressure digestion tank for digestion. The principle is to use the strong oxidation of nitric acid or hydrogen peroxide to destroy the molecular chains of biological samples, so that It dissolves into a solution, and then enters ICP-MS for detection. Such methods usually have higher requirements on the number of samples, and the general digestion sample is at least about 0.1g. Also, unnecessary impurity elements are introduced during the digestion process.

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is a technique for direct introduction of solid samples. Its basic principle is to focus the laser beam on the surface of the sample to dissolve and vaporize it, and the etched particles are carried by the carrier gas. ionized in the plasma, and then analyzed and detected by the mass spectrometer system. As an introduction method suitable for various types of solid samples, combined with inductively coupled plasma mass spectrometry (ICP-MS) with less interference and high sensitivity, it has opened up a new field of mass spectrometry analysis technology.

The LA-ICP-MS technology has the following advantages: (1) in-situ, real-time and rapid analysis advantages; high sensitivity and good spatial resolution. (2) The range of samples that can be analyzed is very wide, and almost all samples can be ablated by lasers. (3) Solid samples can be measured directly without decomposition, which improves the sampling efficiency. (4) Different methods of analysis can be adopted, such as micro-area analysis, overall analysis or probe analysis. (5) There are almost no requirements for samples. The above-mentioned solid sample direct introduction technology (i.e. solid sample injection method) reduces the cumbersome sample preparation process, not only saves time but also reduces the possibility of pollution, avoids the dilution effect in solution preparation, and is beneficial to reduce the detection limit, while the introduction of plasma The bulk dry aerosol results in less interference in mass spectrometry than solution methods.

However, in the past, the LA-ICP-MS method used solid standard samples in the analysis process, or used solution standard samples for calibration. Solid standard samples were prepared by powder pressing, melting and sintering, etc., but there was no such method for biological samples. Great standard preparation. The accuracy and precision of the analysis results are seriously affected by the repeatability of the laser ablation process, the uniformity of the solid sample, the physical properties and surface state of the solid sample itself, and the fractionation effect of elements. Therefore, how to accurately determine the content of trace elements in biological samples by LA-ICP-MS is one of the research hotspots in this field.

Contents of the invention

The present invention aims to overcome the cumbersome detection steps in the traditional wet decomposition method and the problems of standard sample preparation in the existing LA-ICP-MS method. The present invention provides a detection platform for the determination of trace elements in biological samples And detection methods, so that trace elements in biological samples can be quickly and accurately determined.

One aspect of the present invention provides a detection platform for determining trace elements in a biological sample, the detection platform comprising: a refrigeration system for freezing the biological sample to a solid state; performing laser ablation on the biological sample frozen to a solid state a laser ablation system; and an inductively coupled plasma mass spectrometry system for loading the aerosol of the biological sample obtained by laser ablation into the plasma for ionization and detecting the content of trace elements in the biological sample.

The detection platform provided by the present invention can effectively freeze biological samples to a solid state quickly to obtain a solid standard sample suitable for use in the LA-ICP-MS method, and does not introduce any chemical reagents during the detection process, which is environmentally friendly and efficient, and is beneficial to The development of the follow-up inspection process. The detection platform of the present invention has the advantages of simple structure, convenient use and rapid cooling, and can quickly measure the content of trace elements in biological samples.

In the present invention, the refrigeration system includes: a sample tank for storing biological samples; a housing having an opening at the top and accommodating at least one of the sample tanks; a lid through which the laser light penetrates; a refrigeration unit for freezing and maintaining the temperature of the biological sample; and a thermometry unit for measuring the temperature of the biological sample.

The casing provided by the present invention can accommodate multiple sample tanks at the same time, and can simultaneously freeze and keep warm multiple samples through the refrigeration unit, which is conducive to the rapid development of subsequent sample detection and calibration steps, and improves the detection speed. The cover can be completely sealed with the shell to form a closed cavity, and the laser emitted by the laser ablation system can penetrate the cover to perform laser ablation on the frozen to solid biological samples contained in the shell, so as to obtain subsequent LA - Aerosols detected by ICP-MS. Moreover, setting the temperature measurement unit can facilitate the control of the refrigeration unit to keep the frozen biological samples warm.

In the present invention, the refrigerating unit is provided with a refrigerating pipeline for supplying a refrigerating medium into the casing to freeze biological samples, and a device for controlling the refrigerating medium in the refrigerating pipeline according to the temperature detected by the temperature measuring unit. Flow control member for flow rate.

In the present invention, a refrigeration pipeline that provides refrigeration medium to the housing to freeze the biological sample and a flow control member that controls the flow rate of the refrigeration medium in the refrigeration pipeline according to the temperature detected by the above-mentioned temperature measurement unit are used to effectively freeze the biological sample and Keep warm. Preferably, the refrigerating medium may be nitrogen, so as to achieve faster refrigerating.

In the present invention, the refrigerating pipeline includes a refrigerating medium inlet and a refrigerating medium outlet respectively provided on the side wall of the housing, and a cooling medium connected between the refrigerating medium inlet and the refrigerating medium outlet. The pipe body for carrying the sample tank is arranged in the casing; and the flow control member is arranged at the inlet part of the cooling medium.

According to the present invention, the refrigerating medium as a refrigerating source flowing in from the refrigerating medium inlet part flows through the pipe body provided in the casing, and then flows out from the refrigerating medium outlet part. Therefore, the biological samples in the sample tank placed on the tube body can be effectively frozen by the cooling medium circulating in the tube body. Moreover, the flow rate of the cooling medium flowing into the housing can be effectively controlled based on the temperature measured by the temperature measuring unit through the flow control member disposed at the cooling medium inlet, so as to facilitate the insulation of the frozen biological sample. Preferably, the above-mentioned pipe body can be formed into an M shape, so as to achieve more uniform cooling.

In the present invention, the temperature measuring unit includes a temperature measuring instrument connected with the sample tank.

According to the present invention, the temperature of the biological sample in the sample tank can be effectively detected by the thermometer connected with the sample tank, which is beneficial to realize the heat preservation function. Preferably, the thermometer can be a temperature measuring resistor connected to the sample tank.

In the present invention, the inductively coupled plasma mass spectrometry system includes a carrier gas pipeline for providing carrier gas to the biological sample in the housing, and an inductively coupled plasma mass spectrometer connected to the carrier gas pipeline.

According to the present invention, the carrier gas can be provided to the biological sample in the casing through the carrier gas pipeline, so that the aerosol of the biological sample obtained by laser ablation is loaded into the plasma by the carrier gas and ionized for subsequent detection.

In the present invention, the carrier gas pipeline includes a carrier gas inlet and a carrier gas outlet respectively provided on the side wall of the housing, the carrier gas inlet is connected to a carrier gas supply source, and the carrier gas The gas outlet part is connected with the inductively coupled plasma mass spectrometer.

In the present invention, the carrier gas pipeline includes a carrier gas inlet and a carrier gas outlet respectively arranged on the side wall of the casing, the carrier gas inlet is connected with the carrier gas supply source to provide carrier gas into the casing, and the carrier gas outlet The part is connected to an inductively coupled plasma mass spectrometer to provide the latter with an aerosol of a biological sample carried by a carrier gas. That is, after the laser ablation is completed, a carrier gas is introduced into the casing, and the aerosol obtained by the ablation is brought into an inductively coupled plasma mass spectrometer by the carrier gas for subsequent detection. The detection method is further simplified to ensure the accuracy of the detection result. Preferably, the carrier gas may be an inert gas such as helium or argon. More preferably, the carrier gas may be a mixed gas of helium and argon.

The present invention also provides a detection method using the above-mentioned detection platform, comprising:

(1) The biological samples and standard solutions frozen to a solid state through the refrigeration system are subjected to laser ablation treatment through a laser ablation system to form aerosols of biological samples and standard solutions respectively;

(2) Load the aerosol obtained in step (1) into the plasma by an inductively coupled plasma mass spectrometry system and ionize it for detection, and directly obtain the ionic strength values of the biological sample and standard solution, according to the The ionic strength value of the standard solution obtains the calibration curve about the ionic strength value-concentration of the standard solution, and according to the relational expression obtained from the calibration curve, converts the ionic strength value of the biological sample to obtain the content of trace elements.

In the method of the present invention, due to the use of the above-mentioned detection platform, the biological sample and the standard solution can be quickly frozen to a solid state, and then the standard solution and the biological sample can be tested by the laser ablation system and the inductively coupled plasma mass spectrometry system, and the The solution is used as a quantitative basis for quantitative analysis of biological samples. Since the standard sample and the sample are analyzed at the same time under a unified low temperature state, the stability of the data can be ensured and the accuracy of the data can be improved, so that the measurement value of the trace elements in the biological sample can be quickly and accurately obtained, and it overcomes the traditional humidity The detection steps are cumbersome in the decomposition means of the method, and the problems of the standard sample preparation in the existing LA-ICP-MS method.

In the present invention, in the step (1), the laser ablation system adopts the line scan ablation mode, and the wavelength of the laser emitted by the laser ablation system is 213mm, the pulse frequency is 20Hz, and the ablation aperture is 15-200μm , The erosion time is 15-200 seconds.

By selecting the parameters of the above laser ablation system, the aerosol of the biological material can be obtained effectively through laser ablation.

In the present invention, in the step (2), the inductively coupled plasma mass spectrometry system collects data in the time-resolved mode of peak jumping, and in the inductively coupled plasma mass spectrometry system, the RF power is 1000w, and the sampling The depth is 9mm, the working gas is argon, the plasma gas flow rate is 15.0L/min, the carrier gas flow rate is 1.4L/min, the data acquisition time is 120 seconds, and the integration time is 60 seconds.

By selecting the parameters of the above-mentioned inductively coupled plasma mass spectrometry system, the aerosol of the biological material obtained through laser ablation can be effectively detected.

Beneficial effects of the present invention:

Under the cooling action of the refrigeration source, the biological samples and standard solutions are quickly condensed into a solid state, so that the samples can be quickly and accurately quantitatively analyzed. The refrigeration system is simple in structure, easy to use, rapid in refrigeration, and keeps the low temperature constant. Moreover, placing multiple sample holders can analyze multiple groups of samples and standard solutions at the same time. Simultaneously analyze standard samples and samples under a unified low temperature state to ensure data stability and improve data accuracy. This method solves the problem of cumbersome operation steps in the analysis of biological samples by the traditional digestion method, and does not introduce any chemical reagents, which is more environmentally friendly and efficient. It also solves the problem of too high reagent blank during sample preparation and improves the detection sensitivity. This method also solves the problem that it is difficult to prepare solid standard samples in the previous LA-ICP-MS analysis. Compared with the traditional preparation of LA solid standard samples, the preparation of solution standard samples is simpler, faster and more accurate. The uniformity of the standard sample has also been guaranteed to the greatest extent. Moreover, various carrier gases can be filled in the shell to reduce the interference of polyatomic particles.

Description of drawings

Fig. 1 shows a schematic diagram of a refrigeration system of a detection platform for determining trace elements in a biological sample according to an embodiment of the present invention;

Fig. 2 is the schematic diagram of the sample tank used in the refrigeration system shown in Fig. 1;

Fig. 3 is a schematic diagram of a refrigeration unit used in the refrigeration system shown in Fig. 1;

Fig. 4 is a calibration curve prepared in an embodiment of detection using the detection platform for determining trace elements in biological samples of the present invention.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and the following specific embodiments. It should be understood that the following embodiments and/or accompanying drawings are only used to illustrate the present invention rather than limit the present invention.

According to one aspect of the present invention, a detection platform for determining trace elements in a biological sample is provided, the detection platform includes: a refrigeration system for freezing the biological sample to a solid state; A laser ablation system for ablation; and an inductively coupled plasma mass spectrometry system for loading the aerosol of the biological sample obtained by laser ablation into the plasma for ionization, and detecting the content of trace elements in the biological sample.

The detection platform provided by the present invention can effectively freeze biological samples to a solid state quickly to obtain a solid standard sample suitable for use in the LA-ICP-MS method, and does not introduce any chemical reagents during the detection process, which is environmentally friendly and efficient, and is beneficial to The development of the follow-up inspection process. The detection platform of the present invention has the advantages of simple structure, convenient use and rapid cooling, and can quickly measure the content of trace elements in biological samples.

Fig. 1 shows a schematic diagram of a refrigeration system of a detection platform for determining trace elements in biological samples according to an embodiment of the present invention; Fig. 2 is a schematic diagram of a sample tank used in the refrigeration system shown in Fig. 1 . As shown in Figures 1 and 2, the refrigeration system includes: a sample tank 6 for storing biological samples; a housing 2 having an opening at the top and accommodating at least one sample tank 6; capable of sealing the opening and allowing the laser ablation system The cover 1 through which the emitted laser light penetrates; the refrigeration unit for freezing and keeping the biological sample warm; and the temperature measurement unit for measuring the temperature of the biological sample. The laser ablation system may be a commonly used laser ablation system in the prior art, and a detailed description of its structure is omitted here.

Multiple sample tanks 6 can be accommodated in the casing 2 at the same time, and multiple samples can be frozen and kept warm through the refrigeration unit at the same time. The cover 1 can be completely sealed with the housing 2 to form a closed cavity, for example, a cube-shaped closed cavity in the embodiment shown in FIG. 1 . In addition, the laser light emitted by the laser ablation system can penetrate the cover body 1 to perform laser ablation on the biological sample frozen to a solid state contained in the housing 2, so as to obtain the aerosol for subsequent detection by the LA-ICP-MS method. Moreover, setting the temperature measurement unit can facilitate the control of the refrigeration unit to keep the frozen biological samples warm.

Specifically, the above-mentioned housing 2 is made of low-temperature resistant and high-strength stainless steel material, which can withstand low temperatures of about -50° C. without deformation. The material of the cover body 1 is transparent and bubble-free quartz glass, which allows the laser energy to pass through without rapidly attenuating and focus on the surface of the biological material sample.

In addition, the sample tank 6 can be made of double-sided polished aluminum nitride ceramics, and a smooth concave tank body 7 is processed on one side of the sample tank 6 for placing biological samples or standard solutions. Aluminum nitride ceramics have a large thermal conductivity, are resistant to strong acids and alkalis, are not easily corroded by samples, and are not easily deformed and broken at low temperatures. The sample tank made of it can conduct heat quickly and uniformly, can cool the whole tank body evenly and can maintain a low temperature state better. And it can carry various acidic and alkaline samples, and can be used repeatedly. Compared with other materials such as stainless steel and alumina, it shows its excellent performance.

In addition, the above-mentioned refrigeration unit is equipped with a refrigeration pipeline for supplying a refrigeration medium into the housing 2 to freeze biological samples, and a flow control member for controlling the flow rate of the refrigeration medium in the refrigeration pipeline according to the temperature detected by the temperature measurement unit, so that Efficiently freezes and incubates biological samples. In one embodiment of the present invention, the refrigerating medium may be nitrogen, so as to achieve faster refrigerating.

Specifically, FIG. 3 is a schematic diagram of a refrigeration unit used in the refrigeration system of the embodiment shown in FIG. 1 . In this embodiment, nitrogen gas is used as a cooling source. As shown in Fig. 1 and Fig. 3, the above-mentioned refrigerating pipeline includes a nitrogen gas inlet pipe 4 as a refrigerant inlet part and a nitrogen gas output pipe 4' as a refrigerant outlet part respectively arranged on the side wall of the housing 2, and connecting A pipe body 10 for placing the sample tank 6 is disposed in the housing 2 between the nitrogen gas input pipe 4 and the nitrogen gas output pipe 4 ′. In this embodiment, the refrigeration pipeline can be made of stainless steel pipes, for example. And the flow control member 5 is arranged at the nitrogen input pipe 4 . In this embodiment, the flow control member 5 may be, for example, a flow control valve.

As shown by the arrow in Fig. 3, the refrigerating medium such as nitrogen as the cooling source flowing in from the nitrogen inlet pipe 4 flows out from the nitrogen outlet pipe 4' after passing through the pipe body 10 arranged in the housing 2. Therefore, the biological sample in the sample tank 6 placed on the tube body 10 can be effectively frozen by the cooling medium circulating in the tube body 10 . Moreover, the flow rate of the cooling medium flowing into the casing 2 can be effectively controlled based on the temperature measured by the above-mentioned temperature measuring unit through the flow control valve 5 arranged on the nitrogen gas input pipe 4, so as to facilitate the biological sample after freezing. insulation. Preferably, as shown in FIG. 3 , the above-mentioned pipe body 10 can be formed into an M shape, so as to achieve more uniform cooling. However, the shape of the tube body 10 is not limited thereto, as long as the biological material placed thereon can be frozen and kept warm. In addition, an appropriate amount of thermal insulation material can be filled in the gap between the refrigeration pipeline and the housing 2 to ensure a constant low temperature.

The main principle of the above-mentioned refrigeration unit is to use the rapid refrigeration ability of liquid nitrogen to quickly freeze the sample and standard solution and maintain a constant state at a required temperature, such as -25°C. Any suitable method may therefore be used to solve the problem of refrigeration and insulation.

It should be possible to place 4 to 6 sample tanks 6 at one time on the refrigeration system. The sample tank 6 is in direct contact with the refrigeration unit, and the flow rate of liquid nitrogen is controlled through the flow control valve 5 connected to the nitrogen input pipe 4 to ensure that the temperature of the sample tank 6 is constant at -25°C. A temperature measuring resistor 8 is placed at one end of the sample tank 6 for temperature monitoring. That is, the present invention uses nitrogen as a cooling source, controls the flow rate of nitrogen with the flow control valve 5 , and monitors the temperature change with the temperature measuring resistor 8 to keep it in the range of -25°C.

Referring to FIG. 2 , the above-mentioned temperature measuring unit may include a temperature measuring instrument 8 connected to the sample tank 6 . In this embodiment, the thermometer 8 can be, for example, a temperature measuring resistor connected to the sample tank 6 .

In addition, in the present invention, the above-mentioned inductively coupled plasma mass spectrometry system includes a carrier gas pipeline for supplying the biological sample in the casing 2 and an inductively coupled plasma mass spectrometer connected to the carrier gas pipeline. The inductively coupled plasma mass spectrometer may be, for example, an inductively coupled plasma mass spectrometer commonly used in the prior art, and a detailed description of its structure is omitted here. The carrier gas can be provided to the biological sample in the casing 2 through the carrier gas pipeline, so that the aerosol of the biological sample obtained by laser ablation is loaded into the plasma by the carrier gas and ionized for subsequent detection.

As shown in Figure 1, the above-mentioned carrier gas pipeline includes a carrier gas inlet 3 and a carrier gas outlet 3' respectively arranged on the side wall of the housing 2, and the carrier gas inlet 3 is connected to a carrier gas supply source omitted from the illustration. To provide carrier gas into the housing 2, and the carrier gas outlet 3' is connected to the inductively coupled plasma mass spectrometer omitted from the illustration to provide the latter with the aerosol of the biological material loaded by the carrier gas for subsequent detection .

The gas filled in the above-mentioned carrier gas pipeline includes carrier gas and/or protective gas. The main function of the flushing gas is to isolate the interference factors such as moisture, air and dust, prevent the sample from volatilizing moisture at low temperature, and use the carrier gas to The ablated particles are carried into the plasma.

The present invention also provides a detection method using the above-mentioned detection platform, comprising:

(1) The biological samples and standard solutions frozen to a solid state through the refrigeration system are subjected to laser ablation treatment through a laser ablation system to form aerosols of biological samples and standard solutions respectively;

(2) Load the aerosol obtained in step (1) into the plasma by an inductively coupled plasma mass spectrometry system and ionize it for detection, and directly obtain the ionic strength values of the biological sample and standard solution, according to the The ionic strength value of the standard solution obtains the calibration curve about the ionic strength value-concentration of the standard solution, and according to the relational expression obtained from the calibration curve, converts the ionic strength value of the biological sample to obtain the content of trace elements.

According to the present invention, the biological sample and the standard solution are rapidly condensed into a solid state under the refrigeration effect of the refrigeration source, thereby performing rapid and accurate quantitative analysis on the sample. The refrigeration system is simple in structure, easy to use, rapid in refrigeration, and keeps the low temperature constant. Moreover, placing multiple sample tanks 6 can analyze multiple groups of samples and standard solutions at the same time. Simultaneously analyze standard samples and samples under a unified low temperature state to ensure data stability and improve data accuracy. This method solves the problem of cumbersome operation steps in the analysis of biological samples by the traditional digestion method, and does not introduce any chemical reagents, which is more environmentally friendly and efficient. It also solves the problem of too high reagent blank during sample preparation and improves the detection sensitivity. This method also solves the problem that it is difficult to prepare solid standard samples in the previous LA-ICP-MS analysis. Compared with the traditional preparation of LA solid standard samples, the preparation of solution standard samples is simpler, faster and more accurate. The uniformity of the standard sample has also been guaranteed to the greatest extent. Moreover, various carrier gases can be filled in the casing 2 to reduce the interference of polyatomic particles.

And, in the above step (1), the laser ablation system adopts the line scan ablation mode, and the wavelength of the laser emitted by the laser ablation system is 213mm, the pulse frequency is 20Hz, the ablation aperture is 15-200μm, and the ablation time is 15 to 200 seconds. Since biological materials are organic materials with relatively soft texture and rich in water, it is necessary to appropriately reduce the energy of the laser and increase the spot size when selecting laser parameters. Make the irradiation surface of the laser as large as possible, the irradiation depth is shallow, and it cannot penetrate biological materials. Therefore, through the selection of the parameters of the above-mentioned laser ablation system, the laser ablation of biological materials can be effectively performed.

In addition, in the above step (2), the inductively coupled plasma mass spectrometry system collects data in a time-resolved mode of peak hopping, and in the inductively coupled plasma mass spectrometry system, the RF power is 1000w, and the sampling depth is 9mm, The working gas is argon, the plasma gas flow rate is 15.0 L/min, the carrier gas flow rate is 1.4 L/min, the data acquisition time is 120 seconds, and the integration time is 60 seconds. By selecting the parameters of the above-mentioned inductively coupled plasma mass spectrometry system, the aerosol of the biological material obtained through laser ablation can be effectively detected.

Specifically, the present invention can adopt the LA-ICP-MS method to measure trace elements in biological samples, including the following steps:

a) Take a biological sample of appropriate size and place it directly in the groove 7 of the sample tank 6;

b) Take a certain amount of standard solution and place it in another sample tank 6. Multiple sample tanks 6 can be added as needed to place different biological samples or standard solutions; and connect a temperature measuring resistance or a thermometer 8. If necessary, multiple temperature measuring resistors or thermometers can be connected 8;

c) Place these sample wells 6 on top of the stainless steel tubes 10 of the refrigeration unit. Cover and seal the cover body 1, and fill the carrier gas pipeline with helium;

d) Open the flow control valve 5, rush into the nitrogen gas quickly, observe the temperature display of the thermometer 8, and reduce the nitrogen pressure when it is close to -25°C, and keep it at about -25°C;

e) Turn on the laser ablation system in the line scan ablation mode, and collect data in the time-resolved mode of peak jumping by ICP-MS. The calibration curve was made with the frozen standard solution, and the relational expression of the calibration curve was obtained. The same method is used to detect the biological sample, and the content of trace elements in the biological sample can be calculated according to the established relational formula and the ionic strength of the biological sample.

In this step e), specifically, the aerosol of the biological sample and the standard solution obtained by laser ablation is loaded into the plasma and ionized for detection, and the ionic strength values of the biological sample and the standard solution are directly obtained. The ionic strength value is used to obtain the calibration curve about the ionic strength value-concentration of the standard solution, and the content of trace elements in the biological sample is obtained by converting the ionic strength value of the biological sample according to the relationship obtained from the calibration curve.

And the above-mentioned ionic strength value can be obtained by, for example, separating ions with a quadrupole rod and detected by a photomultiplier detector. Simply speaking, high-speed electrons are used to hit gaseous molecules or atoms, and the ionized positive ions are accelerated into the mass analyzer, and then press The mass-to-charge ratio (m/z) is collected and recorded in order of magnitude.

The detection method of the present invention can measure trace elements of biological samples without digesting the samples, and the test results are consistent with the results obtained by microwave digestion-inductively coupled plasma mass spectrometry within the error range, and are reasonable and feasible.

The present invention will be described in more detail through specific embodiments below in conjunction with FIG. 1 to FIG. 3 .

Example 1

This embodiment provides a refrigeration system for laser ablation. As shown in Figure 1, a box with an upper opening is made of sus304 stainless steel as the shell 2, and two small holes are punched on the upper side of the shell 2, and the stainless steel conduits 3, 3' are inserted and the conduits 3, 3' are connected to the shell. Body 2 is firmly welded to ensure sealing. Wherein, the conduit 3 is connected to a decompression valve and a helium cylinder not shown in the figure to be filled with carrier gas and/or protective gas, and the conduit 3' is connected to an inductively coupled plasma mass spectrometer not shown in the figure.

Punch two holes on the side bottom of the housing 2. The hollow stainless steel pipe 10 is bent into an M shape by thermal processing, as shown in FIG. 3 , and one side is guaranteed to be flat without warping. Put the M-type stainless steel tube 10 into the housing 2 with the flat surface upward, and connect the two ends of the stainless steel tube 10, namely the nitrogen gas input pipe 4 and the nitrogen gas output pipe 4', to the two small holes at the bottom of the housing 2 respectively, And it is firmly welded with the housing 2 to ensure sealing. And a flow control valve 5 is connected to the nitrogen input pipe 4 . In the gap between the stainless steel pipe 10 and the housing 2, an appropriate amount of thermal insulation material can be filled. Subsequently, a piece of transparent and bubble-free double-sided polished quartz glass can be used as the cover 1 of the refrigeration system. A section of rubber gasket can be installed at the connection between the cover 1 and the shell 2, and the cover 1 and the shell can be connected with a clip. Body 2 is sealed.

Aluminum nitride ceramics polished on both sides were used as the sample tank 6 . A smooth concave groove body 7 is processed on one side of the sample groove 6 for placing samples or standard solutions. And a temperature probe can also be arranged around the tank body 7 .

In this application example, a liver sample was used to test the Cd in it to verify the reliability of the equipment and method.

Adopt LA-ICP-MS method to measure the method step of trace element in the biological sample as follows:

1. Soak the sample tank 6 in 5% nitric acid for 2 hours, take it out, rinse it with ultrapure water and air dry;

2. Take a liver sample of a suitable size, for example, about 1mm long and 0.5mm wide, and place it directly in the tank body 7 of the sample tank 6;

3. Take 5 mL of 2 μg/g, 4 μg/g, 6 μg/g, and 10 μg/g Cd standard solutions, place them in four sample tanks 6, and connect them with temperature measuring resistors 8;

4. These sample tanks 6 are placed on the stainless steel pipe 10 . Cover the cover body 1 and seal it. And fill helium in the carrier gas input pipe 3;

5. Open the nitrogen flow control valve 5, quickly fill nitrogen with a pressure of 0.3mpa, observe the temperature display of the thermometer 8, when it is close to -25°C, reduce the nitrogen pressure to 0.1mpa, and keep it at -25°C about. At this point, both the biological sample and the standard solution have been frozen;

6. Turn on the laser ablation system in the line scan ablation mode, and ICP-MS collects data in the time-resolved mode of peak jumping;

7. Make a calibration curve with frozen standard solution, and obtain the relational formula of the calibration curve. Samples were tested in the same way. According to the established relationship and the ionic strength of the sample, the content of trace elements in the biological sample can be calculated. Among them, the frozen standard solution is first scanned to obtain a set of element data of a line, and the data points of a standard solution are obtained after taking the average value. After testing several concentrations of the standard solution, a calibration curve is drawn, and then the sample is tested to obtain After the sample data, the corresponding concentration values were calculated through the calibration curve.

Among them, the optimal setting of each parameter in the LA-ICP-MS method is as follows: the wavelength of the laser emitted in the laser ablation system is 213 mm, the pulse frequency is 20 Hz, the ablation aperture is 200 μm, and the ablation time is 200 s; the inductively coupled plasma mass spectrometry system Middle: The RF power is 1000w, the sampling depth is 9mm, the working gas is argon, the plasma gas flow rate is 15.0L/min, the carrier gas flow rate is 1.4L/min, the data acquisition time is 120s, and the integration time is 60s.

The data measured in the embodiment 1 are listed in Table 1, and the calibration curve in Fig. 4 can be obtained according to the data in Table 1.

Table 1

Combining Table 1 and Figure 4, it can be seen that the standard solution line scan detects four points, and after taking the average value of the four points, take the average detection intensity as the ordinate, and the configured concentration of Cd as the abscissa, and the corresponding standard curve calibration curve can be drawn The equation is , the equation of calculating the corresponding calibration curve is y=884.43x, and the correlation coefficient of the calibration curve is 0.996. The sample line scanning results are shown in Table 2.

Table 2

The first point Second point third point fourth point Fifth sixth point seventh point test strength 5322 7633 5479 2689 5834 2699 3396 conversion result 6.02 8.66 6.19 3.04 6.60 3.05 3.84

From the above results, it can be seen that the standard curve of this method has good linearity and can clearly understand the distribution of trace elements in biological samples. And the time taken by this method is only one-third of the traditional analysis method, and no chemical reagents are introduced. This method solves the problem of cumbersome operation steps in the analysis of biological samples by the traditional digestion method, and does not introduce any chemical reagents, which is more environmentally friendly and efficient. It also solves the problem of too high reagent blank during sample preparation and improves the detection sensitivity. This method also solves the problem that it is difficult to prepare solid standard samples in the previous LA-ICP-MS analysis. Compared with the traditional preparation of LA solid standard samples, the preparation of solution standard samples is simpler, faster and more accurate. The uniformity of the standard sample has also been guaranteed to the greatest extent.

Claims (10)

1. A kind of 1. detection platform for being used to measure trace element in biological sample, it is characterised in that

   The detection platform includes：

   The biological sample and standard solution are refrigerated to solid refrigeration system；

   The laser ablation system for carrying out Direct Laser to being refrigerated to solid biological sample and standard solution and degrading；And

   Biological sample and the aerosol of standard solution for laser ablation to be obtained are loaded into ionization in plasma and examine The inductivity coupled plasma mass spectrometry system of the Determination of trace element contents in the biological sample is surveyed,

   The refrigeration system includes：

   Store the sample cell of the aluminium nitride ceramics of biological sample and freezing biological sample and standard solution are freezed simultaneously Insulation and the refrigeration unit directly contacted with the sample cell.
2. 2. detection platform according to claim 1, it is characterised in that the refrigeration system further includes：

   There is opening at top and accommodate the housing of at least one sample cell；

   The lid of the opening and the laser penetration for allowing the laser ablation system to send can be sealed；And

   Temperature measuring unit for the temperature for measuring the biological sample.
3. 3. detection platform according to claim 2, it is characterised in that the refrigeration unit possesses for into the housing Refrigerant is provided to freeze the refrigeration pipeline of biological sample and the system according to the temperature control that the temperature measuring unit detects The flow control member of the flow velocity of refrigerant in cold pipeline.
4. 4. detection platform according to claim 3, it is characterised in that the refrigeration pipeline includes being respectively arranged on the housing Side wall on refrigerant-medium inlet portion and refrigerant outlet portion and be connected to the refrigerant-medium inlet portion and refrigeration be situated between Between matter outlet portion and be arranged in the housing be used for load the tube body of the sample cell；And the flow control member is set In the refrigerant-medium inlet portion.
5. 5. detection platform according to claim 2, it is characterised in that the temperature measuring unit includes being connected with the sample cell Temperature measurer.
6. 6. detection platform according to claim 2, it is characterised in that the inductivity coupled plasma mass spectrometry system possesses For the inductive coupling for providing the biological sample in the housing gas-carrier pipeline of carrier gas and being connected with the gas-carrier pipeline Plasma mass spectrograph.
7. 7. detection platform according to claim 6, it is characterised in that the gas-carrier pipeline includes being respectively arranged on the housing Side wall on carrier gas inlet portion and carrier gas outlet portion, the carrier gas inlet portion is connected with carrier gas supply source, and the carrier gas goes out Oral area is connected with the icp ms.
8. A kind of 8. detection method using detection platform according to any one of claim 1 to 7, it is characterised in that bag Include：

   （1）Solid biological sample and standard solution will be refrigerated to via refrigeration system, laser is carried out by laser ablation system Processing is degraded, forms the aerosol of biological sample and standard solution respectively；

   （2）By inductivity coupled plasma mass spectrometry system by step（1）The aerosol of middle acquisition is loaded into plasma It is detected after middle ionization, the ion-intensity values of the biological sample and standard solution is directly obtained, according to the standard solution Ionic strength be worth to the calibration curve on ion-intensity values-concentration of the standard solution, and according to from the calibration The relational expression that curve obtains converts to obtain the trace element in the biological sample with the ion-intensity values of the biological sample Content.
9. 9. detection method according to claim 8, it is characterised in that in the step（1）In, the laser ablation system Pattern is degraded using line scanning, and the wavelength of laser that sends of the laser ablation system is 213mm, pulse frequency 20Hz, Aperture is degraded for 15~200 μm, degrades the time for 15~200 seconds.
10. 10. detection method according to claim 8 or claim 9, it is characterised in that in the step（2）In, the inductive coupling Plasma mass system is to jump the time-resolved mode gathered data at peak, and in the inductivity coupled plasma mass spectrometry system In, RF power is 1000w, and sampling depth 9mm, working gas is argon gas, and plasma flow amount is 15.0L/ minutes, carrier gas Flow is 1.4 L/ minutes, and data acquisition time is 120 seconds, and the time of integration is 60 seconds.