CN103439316A - Air-pressure type zero-waste-liquid-discharging atomic spectrum or plasma mass spectrum sample injection system - Google Patents

Abstract

The invention discloses an air-pressure type zero-waste-liquid-discharging atomic spectrum or plasma mass spectrum sample injection system which comprises a test sample introduction device, an atomizer and a fog chamber, wherein the test sample introduction device mainly comprises a container, a container cover connected with the container in an airtight manner, a test sample pipe and a sample injection air pipe; the atomizer has a double-layer structure with an inner pipe and an outer pipe; the inner pipe is a capillary which is sleeved in a stainless steel pipe; one end of the capillary extends out of the atomizer, runs through the container cover in the test sample introduction device in the airtight manner and extends into the test sample pipe; the inner diameter of a spraying opening of the atomizer is 0.3-0.4mm; the outer diameter of the capillary is 90-95 percent of the inner diameter of the spraying opening of the atomizer; a distance between the end socket of one end, which is close to the spraying opening, of the capillary and the spraying opening is 0.2-0.4mm; the fog chamber is provided with two ports, one of the ports is connected with the outer pipe of the atomizer in the airtight manner, and the other of the ports is connected with the sample injection end of an atomic spectroscope or a plasma mass spectroscope.

Description

Pneumatic Zero Liquid Discharge Atomic Spectrometry or Plasma Mass Spectrometry Sampling System

technical field

The invention relates to a sampling system, in particular to an air pressure zero-waste discharge atomic spectrum or plasma mass spectrometry sampling system.

Background technique

Existing sampling systems for analytical instruments such as atomic absorption spectrometers and plasma mass spectrometers mainly include sample introduction devices, nebulizers and spray chambers. However, the atomization efficiency of the nebulizer of the existing sampling system is not high, and the atomization efficiency is usually about 1 to 3%. Therefore, in addition to the port connected to the nebulizer and the port connected to the light source of the instrument , a waste liquid discharge port is also provided, and the large mist drops are discharged from the mist chamber through the discharge port. In this way, due to the low atomization efficiency, on the one hand, a larger sample volume is required to complete the detection (usually in the prior art The sample injection volume is about 10mL), which leads to an increase in the detection cost. In addition, when the sample solution is small, the detection task cannot be completed; on the other hand, due to the low atomization efficiency, more waste liquid is discharged, which is not environmentally friendly.

Contents of the invention

The technical problem to be solved by the invention is to provide a gas pressure zero-waste discharge atomic spectrometer or plasma mass spectrometer sampling system. The sampling system has the advantages of simple structure, less sample demand, high atomization efficiency and zero waste liquid discharge.

The air pressure zero-waste discharge atomic spectrometry or plasma mass spectrometry sampling system of the present invention includes a sample introduction device, a nebulizer and a spray chamber, wherein:

The described sample introduction device comprises a container and a container cover airtightly connected with the container, a sample tube for holding a sample solution is built in the container, and one end of the sample gas pipe is airtightly passed through the container cover and stretched into the container, The other end is connected to the sample gas source;

The atomizer has a double-layer structure with an inner tube and an outer tube, and a carrier gas tube is connected to the outer tube; the inner tube is a capillary tube, and a stainless steel tube is set on the capillary tube, and one end of the capillary tube protrudes from the atomizing tube. and airtightly pass through the container cover in the sample introduction device and extend into the sample tube; the inner diameter of the nozzle of the atomizer is 0.3-0.4mm, and the outer diameter of the capillary is 90-90mm of the inner diameter of the nozzle of the atomizer. 95%, the distance between the end of the capillary close to the spout and the spout is 0.2-0.4mm;

The spray chamber has two ports, one of which is airtightly connected with the outer tube of the nebulizer, and the other port is connected with the sampling end of the atomic spectrometer or the plasma mass spectrometer through a pipeline.

In the sample introduction device of the above technical solution, a support ring may be fixed at the bottom of the container, and the sample tube is placed in the support ring to keep it relatively fixed with the container. The sample gas source is usually argon, which can be provided by an argon tank (argon cylinder).

In the above technical solution, the inner diameter of the capillary is preferably 50-100 μm. The inner diameter of the nozzle of the atomizer is preferably 0.33-0.38mm, the outer diameter of the capillary is preferably 90-92% of the inner diameter of the nozzle of the atomizer, and the distance between the end of the capillary near the nozzle and the nozzle is preferably 0.3mm. The stainless steel tube is a miniature stainless steel tube, its caliber is slightly larger than the outer diameter of the capillary, and mainly plays the role of fixing and protecting the capillary, so as to prevent the position of the capillary from being impacted by the airflow ejected from the carrier gas tube to change the position of the capillary and then affect the atomization efficiency . The distance between the end of the stainless steel tube near the nozzle and the nozzle is 1.3-2.3 mm, preferably 1.5-2.0 mm, and the other end extends backward beyond the sample inlet of the nebulizer, generally extending to the outside. beyond the coverage of the tube. A sealing ring is provided between the inner wall of the outer tube of the sampling end of the nebulizer and the outer wall of the inner tube (i.e. capillary), if the stainless steel tube extends backwards beyond the coverage of the outer tube, the Sealing rings are arranged between the inner wall of the outer tube and the outer wall of the stainless steel tube, and between the inner wall of the stainless steel tube and the outer wall of the inner tube, and other sealing rings can also be used to replace the sealing rings. In the technical solution of the present invention, the shorter the length of the capillary and the smaller the inner diameter, the less the amount of sample required for detection. The preferred capillary length is about 50 cm, more preferably 20-35 cm.

In the above technical solution, the fog chamber has only two ports, which can be made of plastic, glass and other materials; the shape and size of the fog chamber can be adjusted as required. Specifically, the port connected to the nebulizer is determined according to the size of the outer tube of the nebulizer, and the port connected to the atomic spectrometer or plasma mass spectrometer is determined according to the size of the sample introduction end of the instrument. Preferably, the spray chamber is designed in a conical shape, wherein the large-diameter port is airtightly connected to the outer tube of the nebulizer, and the small-diameter port is directly or through a pipeline connected to the sample end of the atomic spectrometer or plasma mass spectrometer.

Under the above-mentioned limited conditions, when the system of the present invention is used in conjunction with an atomic spectrometer or a plasma mass spectrometer, the sample injection volume is usually about 10 μL, and the detection can be completed even at 5 μL.

Compared with the prior art, the sampling system of the present invention is characterized in that:

The nebulizer uses a capillary tube with a smaller inner diameter as the inner tube, and at the same time, it is reinforced and protected with a stainless steel tube to prevent the influence of the air flow of the carrier gas tube. The characteristics of the distance between the tip near the end of the nozzle and the nozzle make the atomization efficiency of the sampling system of the present invention reach more than 99%; and because of the high atomization efficiency, the capillary inner diameter is small and the length is short, the present invention When the sample system is used in conjunction with each spectrum analyzer, the sample injection volume only needs 5 μL to complete the detection task, the detection cost is low, and the sample consumption is small; moreover, due to the high atomization efficiency, there is no waste liquid discharge, so the process described in the present invention The spray chamber in the sample system does not need to open a waste liquid discharge port, realizing zero discharge.

Description of drawings

Fig. 1 is the structural representation of an embodiment of the present invention;

Fig. 2 is a schematic structural view of the atomizer in the embodiment shown in Fig. 1;

Fig. 3 is when the sampling system of the present invention is combined with the microwave plasma atomic emission spectrometer, measure the intensity of calcium solution (40mg/L) and the curve of calcium intensity in sub-boiling water, wherein a represents calcium solution (40mg/L) , b represents sub-boiling water.

The labels in the figure are:

1. Sample gas source; 2. Valve; 3. Double gauge pressure gauge; 4. Latex tube; 5. Three-way cock; 6. Sample gas pipe; 7. Container cover; 8. Container; 9. Support ring; 10. 12 capillary; 13 stainless steel tube; 14 sealing ring; 15 outer tube; 16 spout; 17 spray chamber; H indicates the distance between the end of the capillary close to the spout and the spout; the distance between.

Detailed ways

As shown in Figure 1, the sample introduction system of the present invention includes a sample introduction device, an atomizer and a spray chamber 17, wherein:

The sample introduction device is mainly composed of a container 8, a container cover 7 airtightly connected with the container 8, a sample tube 10 for holding a sample solution, a sample gas source 1 and a sample gas tube 6. In the container 8 A cylindrical support ring 9 is affixed to the bottom, and the sample tube 10 is placed in the support ring 9; the outlet of the sample gas source 1 is provided with a double gauge pressure gauge 3, and the sample One end of the trachea 6 airtightly passes through the container cover 7 and stretches into the container 8, and the other end is connected with a three-way cock 5, and an interface of the three-way cock 5 passes through the double latex tube 4 and the outlet of the working air source. The gauge head pressure gauge 3 is connected, and the other port is connected to the atmosphere (it is closed when the sample is injected, and it is connected to the atmosphere after the sample injection is completed);

The atomizer has a double-layer structure with an inner tube and an outer tube 15, and the outer tube 15 (usually made of glass) is connected with a carrier gas tube 11, and the carrier gas tube 11 is connected to the outlet of the sample gas source 1 through the latex tube 4. The double-gauge pressure gauge 3 at the place is connected; the inner tube is a capillary 12, and a miniature stainless steel tube 13 is set on the capillary 12, and one end of the capillary 12 stretches out from the sampling end of the nebulizer and passes through it airtightly. Pass the container cover 7 in the sample introduction device and stretch into the sample tube 10 placed in the container 8, and the described miniature stainless steel tube 13 stretches out the sampling end of the nebulizer backward (equivalent to extending backward to outside the coverage of the outer tube 15); the inner diameter of the atomizer nozzle 16 is 0.3-0.4 mm, the outer diameter of the capillary 12 is 90-95% of the inner diameter of the atomizer nozzle 16, and the capillary 12 is close to The distance H between the end of the spout 16 one end and the spout 16 is 0.2～0.4mm; That is, a seal ring 14 is provided between the outer walls of the capillary 12) to realize the sealing between the inner wall of the outer tube 15 at the sampling end and the outer wall of the micro stainless steel tube 13, and the inner wall of the stainless steel tube 13 and the outer wall of the inner tube (i.e. the capillary 12). tightness between

The mist chamber 17 is conical and has two ports, one is large and the other is small, wherein the large-diameter port is airtightly connected with the outer tube 15 of the nebulizer (there is a sealing ring 14 between them); The small-caliber port is connected directly or through a pipeline to the sampling port of the atomic spectrometer or plasma mass spectrometer (its size is determined according to the size of the sampling port of the atomic spectrometer or plasma mass spectrometer).

In the above embodiment, the sample gas is argon, and the sample gas source 1 can be provided by an argon tank (argon cylinder). Usually, the gas inlet pressure during sample injection is usually 0.03-0.05 MPa. The inner diameter of the capillary 12 as the inner tube of the atomizer is preferably 50-100 μm, and its length is preferably about 50 cm, more preferably 20-35 cm. The inner diameter of the atomizer nozzle 16 is preferably 0.33-0.40mm, the outer diameter of the capillary 12 is preferably 90-92% of the inner diameter of the atomizer nozzle 16, and the end of the capillary 12 near the nozzle 16 is connected to the nozzle. The distance H between 16 is preferably 0.2-0.4 mm. The caliber of the micro-stainless steel tube 13 is slightly larger than the outer diameter of the capillary 12, mainly to fix and protect the capillary 12, so as to prevent the capillary 12 from being impacted by the air flow ejected from the carrier gas tube 11 and causing the position of the capillary 12 to change. The distance G between the end of the miniature stainless steel tube 13 near the nozzle 16 and the nozzle 16 is 1.3-2.3 mm, preferably 1.5-2.0 mm.

When the applicant was doing the experiment, the size of the atomizer in the above system was as follows, and the stability and atomization efficiency of the sampling system with the following size were tested, as follows:

The inner diameter of the atomizer outer tube 15 is 0.6 cm, and the length is 8 cm. The inner diameter of the nozzle 16 is 0.4 mm. The micro-stainless steel tube 13 internal diameter on 12 is 0.4cm, the external diameter is 0.5cm, and is long 8cm; The distance H between the end of described capillary 12 near spout 16 one end and spout 16 is 0.3mm, and described micro-stainless steel tube 13 The distance G between the end near one end of the spout 16 and the spout 16 is 1.7mm. The inner diameter of the latex tube 4 connecting the three-way cock 5 and the sample gas source 1 is 0.2 cm, and the outer diameter is 0.4 cm; the inner diameter of the latex tube 4 connected with the carrier gas tube 11 is 0.2 cm, and the outer diameter is 0.4 cm.

1. The stability of the sampling system

The above-mentioned sampling system is combined with a microwave plasma atomic emission spectrometer. The microwave power of the microwave plasma atomic emission spectrometer is 110W, the high pressure of the multiplier tube is 800V, and the working gas flow rate is 0.9L/min; the carrier gas flow rate of the sampling system is Under the conditions of 0.9L/min and injection pressure of 0.03MPa, the injection flow rate of 5μL/min was used to measure the calcium solution (40mg/L) for 2 hours, and the sub-boiling water was measured for 2 hours under the same conditions. The results are shown in Figure 3 , where the average intensity of 40mg/L calcium solution is 3605 (the intensity after deducting the blank value), the relative standard deviation is 0.98%; the calcium intensity in sub-boiling water is 600, and the relative standard deviation (RSD) is 0.93%.

It can be seen from Figure 3 that the emission intensity distribution of calcium is relatively concentrated, the stability is good, and the RSD is less than 1%. This not only fully reflects the feasibility of combining the sampling system of the present invention with a microwave plasma atomic emission spectrometer, but also lays a solid foundation for the joint research of the sampling system of the present invention and other spectrometers.

While adopting the calcium solution of the above-mentioned concentration measured by the sampling system of the present invention and the microwave plasma atomic emission spectrometer, the calcium solution of the above-mentioned concentration is also adopted MPT-AES (1020 type, Jilin Changchun Little Swan Instrument Factory) Measured, the measurement conditions are the same as the foregoing, all are: at microwave power, it is 110W, the high pressure of the multiplier tube is 800V, the working gas flow rate is 0.9L/min, the carrier gas flow rate is 0.9L/min, self-priming type injection (into The flow rate of the sample is 872 μL/min), and the transfer pipe is heated, followed by condensation, concentrated sulfuric acid drying and other complex processes for sample injection. The comparison results are shown in Table 1.

Table 1 The comparison between the sampling system of the present invention and the MPT-AES commodity instrument sampling system

It can be seen from Table 1 that the amount of sample required by the present invention is only 2/1000 of the sample amount of MPT-AES, and the measurement accuracy is better.

2. The atomization efficiency of the sampling system

The atomization efficiency (NE) is calculated according to the following formula:

Atomization efficiency (NE)={[(m1－m2)－(M2－M1)]÷(m1－m2)}×100%

In the work, m1 is the quality of the solution before injection, m2 is the quality of the solution after a certain time of injection (in this experiment, the injection time of 2, 3 and 5 hours is used), M1 is the quality of the spray chamber before injection, and M2 is The quality of the spray chamber after a certain time of injection (here, the injection time is the same as m2).

In this experiment, the injection time t was 2, 3 and 5 hours, and the atomization efficiency obtained is shown in Table 2.

Table 2 Atomization efficiency of sampling system

3. The memory effect of the sampling system

The memory effect of the sampling system is caused by the components to be measured remaining on the inner walls of the sampling pipeline, nebulizer, and spray chamber after sampling. If the cleaning is not complete, the subsequent measurement results will be high. The memory effect of the sampling system is often calculated using the following formula:

Memory effect (RE) = [(intensity of the component to be tested after cleaning for a certain period of time - blank value)/(intensity of the component to be tested - blank value)] × 100%

The memory effect of the sampling system of the present invention is measured by the following method: before the sampling, the sampling system is cleaned with sub-boiling water for 1 hour, and the sampling pressure is 0.03MPa, and then the calcium intensity of the sub-boiling water is measured (sub-boiling water measured in the present invention) The average calcium intensity of boiling water is 600 (n=10), that is, the blank value), and then the calcium standard solution is used to inject samples (calcium concentration is 40mg/L), and the average calcium intensity of the calcium standard solution is measured after 30 minutes of injection. The value is 4205 (n=10), and after improving the sub-boiling water for 1 minute, the average strength of calcium measured is 605 (n=10), and the memory effect of the present invention is calculated according to the above formula to be 0.14%. Generally, microanalysis requires a measurement error of about 5% to meet the requirements, but the memory effect error of the present invention is far smaller than the result measurement error. Therefore, the cleaning requirement can be fully met by cleaning for 1 minute using the sampling system of the present invention.

Claims (4)

1. air-pressure type zero discharging of waste liquid atomic spectrum or plasma mass sampling system, comprise sample introduction device, atomizer and fog chamber (17), it is characterized in that:

Described sample introduction device comprises a container (8) and the container cover (7) be tightly connected with this container (8), container (8) is built-in with the coupon (10) for filling sample solution, one end of sample introduction tracheae (6) stretches in container (8) through container cover (7) airtightly, and its other end is connected with sample introduction source of the gas (1);

Described atomizer, for having the double-decker of inner and outer tubes (15), is connected with a carrier gas pipe (11) on outer tube (15); Described inner tube is kapillary (12), at the upper cover of kapillary (12), there are a stainless-steel tube (13), an end of this kapillary (12) stretch out atomizer and stretch in coupon (10) through the container cover (7) in the sample introduction device airtightly; The internal diameter of described atomizer spout (16) is 0.3～0.4mm, the external diameter of described kapillary (12) is 90～95% of atomizer spout (16) internal diameter, and described kapillary (12) is 0.2～0.4mm near the termination of spout (16) one ends and the distance (H) between spout (16);

Described fog chamber (17) has two ports, and one of them port is connected with outer tube (15) impermeability of atomizer, and another port directly or be connected with the sample introduction end of atomic spectrograph or plasma mass spectrograph by pipeline.

2. air-pressure type according to claim 1 zero discharging of waste liquid atomic spectrum or plasma mass sampling system, it is characterized in that: the internal diameter of described kapillary (12) is 50～100 μ m.

3. air-pressure type according to claim 1 zero discharging of waste liquid atomic spectrum or plasma mass sampling system, it is characterized in that: described stainless-steel tube (13) is 1.3～2.3mm near the termination of spout (16) one ends and the distance (G) between spout (16).

4. air-pressure type according to claim 1 zero discharging of waste liquid atomic spectrum or plasma mass sampling system, it is characterized in that: described fog chamber (17) are tapered, its heavy caliber port is connected with outer tube (15) impermeability of atomizer, and small-bore port directly or be connected with the injection port of atomic spectrograph or plasma mass spectrograph by pipeline.

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