Qualitative and semi-quantitative analysis device for methyl antimony in gas phase and liquid phase

Abstract

The invention discloses a qualitative and semi-quantitative analysis device for methyl antimony in a gas phase and a liquid phase. The device comprises a gas sample preparation device used for converting a liquid methyl antimony compound into a gaseous methyl antimony compound through a hydrogenation reaction; the methyl antimony low-temperature trapping device comprises a liquid nitrogen cooled U-shaped chromatographic column and is used for trapping and cold focusing gaseous methyl antimony; the gas chromatography-mass spectrometry system is used for separating and detecting the methyl antimony compound; wherein a gaseous methyl antimony compound generated by the gas sample preparation device is input into the methyl antimony low-temperature trapping device, is heated and then is input into the gas chromatography-mass spectrometry system for qualitative and semi-quantitative analysis. The device disclosed by the invention can be used for simultaneously analyzing gas-phase and liquid-phase samples (such as supernate and headspace gas of a rice field soil enrichment culture), detecting differential distribution of MMSb and DMSb in a liquid phase and TMSb in a gas phase, and providing comprehensive data support for researching migration and transformation of methyl antimony in an environmental medium.

Description

Technical Field

[0001] The present invention relates to a device for qualitative and semi - quantitative analysis of methylantimony in gas and liquid phases, belonging to the field of environmental science and technology. Background Art

[0002] Antimony (Sb), as a metal or metalloid element in Group 15 of the periodic table, has attracted much attention in recent years due to its toxicity and potential carcinogenicity. In the environment, antimony mainly exists in the forms of inorganic antimony and organic antimony. Among them, inorganic antimony mainly includes two forms, Sb(III) and Sb(V), while organic antimony is mainly represented by methylantimony. The migration and transformation of inorganic antimony in the environment have been widely studied, which largely benefits from the convenience of detection methods. When quantitatively detecting Sb(III) and Sb(V), high - performance liquid chromatography (HPLC) coupled with atomic fluorescence spectrometer (AFS) or inductively coupled plasma mass spectrometry (ICP - MS) is a commonly used analytical method. These two methods rely on the separation of inorganic antimony in the sample by HPLC, and usually use potassium hydrogen phthalate (KHP) and ethylenediaminetetraacetic acid (EDTA) as the mobile phase to enhance the separation effect. However, it must be pointed out that although HPLC shows certain advantages in the analysis of inorganic antimony species, the separation of organic antimony, especially methylantimony, faces many challenges. Although there are literatures reporting the successful separation of trimethylantimony (TMSb) by HPLC, it is impossible to effectively separate monomethylantimony (MMSb) and dimethylantimony (DMSb), and the reproducibility of the detection results is often not high due to the poor chromatographic peak shape. Therefore, there are obvious limitations in the current separation and detection of organic antimony, especially methylantimony, based on HPLC technology.

[0003] For the detection of methyl metals or metalloids, the separation based on gas chromatography (GC) combined with gas chromatography - mass spectrometry (GC - MS) or ICP - MS provides an effective means. This method uses the hydrogenation reaction of sodium borohydride under acidic conditions to convert metal or metalloid samples into gaseous forms, so as to achieve more efficient separation through GC. There have been literatures reporting that the separation technology based on GC can excellently separate monomethylantimony, dimethylantimony and trimethylantimony. However, this method also has some technical problems. First, the conventional hydrogenation reaction usually relies on a peristaltic pump to simultaneously feed the carrier, reducing agent and sample into the reaction cell, and this method is often difficult to guarantee accuracy and repeatability. Second, molecular rearrangement may occur during the hydrogenation process, that is, high - methyl (such as trimethyl) metals or metalloids may lose methyl groups during the reaction to form low - methyl compounds (such as monomethyl, dimethyl, inorganic compounds). Therefore, in view of the limitations of existing methods, there is an urgent need to develop a more perfect and reliable methylantimony detection device and method to ensure the accuracy and reliability of analysis results. Summary of the Invention

[0004] The object of the present invention is to provide a device for qualitative and semi - quantitative analysis of methylantimony in gas and liquid phases.

[0005] The object of the present invention is to provide a device for qualitative and semi - quantitative analysis of methylantimony in gas and liquid phases, so as to solve the problems in the prior art such as low separation efficiency of methylantimony compounds (such as methylantimony, dimethylantimony and trimethylantimony), poor reproducibility of detection results, morphological distortion caused by molecular rearrangement during the hydrogenation process, and matrix interference affecting the quantitative accuracy.

[0006] The device for qualitative and semi - quantitative analysis of methylantimony in gas and liquid phases provided by the present invention includes:

[0007] A device for preparing gas samples, which is used to convert liquid methylantimony compounds into gaseous methylantimony compounds through a hydrogenation reaction;

[0008] A low - temperature methylantimony trapping device, which consists of a U - shaped chromatographic column cooled by liquid nitrogen and is used for trapping and cold - focusing gaseous methylantimony;

[0009] A gas chromatography - mass spectrometry (GC - MS) system, which is used for the separation and detection of methylantimony compounds;

[0010] Among them, the gaseous methylantimony compounds generated by the gas sample preparation device are input into the low - temperature methylantimony trapping device, and after heating, they are input into the gas chromatography - mass spectrometry system for qualitative and semi - quantitative analysis.

[0011] In the qualitative and semi - quantitative analysis device of the present invention, the gas sample preparation device includes a continuous - flow hydride generator and a liquid chromatography unit with a quantitative loop;

[0012] Both the continuous - flow hydride generator and the liquid chromatography unit are connected to a reaction coil, and the other end of the reaction coil is sequentially connected to a gas - liquid separator and a gas bag.

[0013] In the qualitative and semi - quantitative analysis device of the present invention, a peristaltic pump in the continuous - flow hydride generator transports acetic acid and sodium borohydride or potassium borohydride to the reaction coil;

[0014] Liquid methylantimony compounds are transported to the reaction coil through a mobile phase;

[0015] The mobile phase is preferably a sodium citrate buffer solution.

[0016] In the qualitative and semi - quantitative analysis device of the present invention, in the low - temperature methylantimony trapping device, the U - shaped trap is filled with 10% SP - 2100 - coated Chromosorb material;

[0017] The inlet of the U-shaped trap is connected to the airbag, and the outlet is connected to the gas chromatography-mass spectrometry system;

[0018] During operation, the U-shaped trap is pre-cooled to -196 °C with liquid nitrogen. Then, a nickel-chromium wire is used to connect to a DC switching power supply, and the temperature of the chromatographic column is heated from -196 °C to 100 °C within 3 minutes, and helium gas is used to blow the gas into the gas chromatography-mass spectrometry system for separation and detection.

[0019] In the qualitative and semi-quantitative analysis device of the present invention, the U-shaped trap is connected to the airbag and the gas chromatography-mass spectrometry system through a six-way valve.

[0020] In the qualitative and semi-quantitative analysis device of the present invention, the six-way valve is respectively connected to He gas and a rotameter, and the rotameter is connected to a diaphragm pump.

[0021] In the qualitative and semi-quantitative analysis device of the present invention, the gas chromatography-mass spectrometry system is connected to the six-way valve to switch the purge gas and the carrier gas to achieve the separation and detection of methylantimony compounds;

[0022] Among them, the mass range of the gas phase mass spectrometry is selected according to the expected mass of the analyzed compound. The electron ionization (EI) ion source mode is used, and the methylantimony compounds are semi-quantified by the selected ion monitoring mode (SIM).

[0023] By combining gas chromatography with cryogenic trapping technology, the present invention overcomes the problem of low separation efficiency of traditional liquid chromatography for monomethylantimony, dimethylantimony and trimethylantimony, realizes the baseline separation of the three methylantimony forms, and significantly improves the chromatographic peak shape and reproducibility.

[0024] The present invention uses sodium citrate buffer solution to optimize the hydrogenation reaction system, effectively reduces the demethylation phenomenon of trimethylantimony during hydrogenation, and avoids the formation of low-methyl or non-methyl antimony compounds (such as SbH3), so as to truly reflect the original morphological distribution of methylantimony in the sample.

[0025] The device of the present invention can simultaneously analyze gas-phase and liquid-phase samples (such as the supernatant and headspace gas of a paddy soil enrichment culture), and detects the differential distribution ([ Figure 3-4 ) with MMSb and DMSb mainly in the liquid phase and TMSb mainly in the gas phase, providing comprehensive data support for studying the migration and transformation of methylantimony in environmental media. Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of the qualitative and semi-quantitative analysis device for methylantimony in the gas phase and liquid phase of the present invention.

[0027] The marks in the figure are as follows:

[0028] 1. Liquid chromatography, 2. Peristaltic pump, 3. Reaction coil, 4. Gas-liquid separator, 5. Dryer, 6. Six-port valve, 7. Diaphragm pump, 8. Rotameter, 9. U-shaped trap, 10. Gas chromatography-mass spectrometry (GC-MS) system.

[0029] Figure 2 It is the HG-LT-GC-MS chromatogram after the hydrogenation of 10 μM (CH3)3SbBr2 under the condition of HCl carrier.

[0030] Figure 3 It is the mass spectrum of SbH3 (Figure a), the mass spectrum of CH3SbH2 (Figure b), the mass spectrum of (CH3)2SbH (Figure c), and the mass spectrum of (CH3)3Sb (Figure d) generated after the hydrogenation of the (CH3)3SbBr2 standard solution.

[0031] Figure 4 It is the antimony species in the supernatant of the paddy soil enrichment culture (Figure a), the mass spectrum of MMSb(III) detected in the enrichment culture supernatant by HT-LT-GC-MS (Figure b), and the mass spectrum of DMSb(III) (Figure c).

[0032] Figure 5 It is the volatilization of antimony species in the paddy soil enrichment culture (Figure a), and the mass spectrum of TMSb(III) detected in the enrichment culture headspace by HT-LT-GC-MS (Figure b). Detailed implementation manners

[0033] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods.

[0034] Unless otherwise specified, the materials, reagents, etc. used in the following examples can all be obtained from commercial sources.

[0035] Example 1. Qualitative and semi-quantitative analysis device for methylantimony in gas phase and liquid phase

[0036] As Figure 1 shown, it is the structural schematic diagram of the qualitative and semi-quantitative analysis device for methylantimony in gas phase and liquid phase provided by the present invention, including: a device for preparing gas samples, which is used to convert liquid methylantimony compounds into gaseous methylantimony compounds through hydrogenation reaction; a methylantimony low-temperature trapping device, including a U-shaped chromatographic column 9 cooled by liquid nitrogen, which is used to trap and cold-focus gaseous methylantimony; a gas chromatography-mass spectrometry (GC-MS) system 10, which is used for the separation and detection of methylantimony compounds. The device of the present invention can separate and detect monomethylantimony, dimethylantimony, and trimethylantimony, and realize the qualitative and semi-quantitative analysis of methylantimony in gas phase and liquid phase.

[0037] Among them, the gas sample preparation device consists of a continuous flow hydride generator and a liquid chromatography unit 1 with a 1 ml quantitative loop. The peristaltic pump 2 in the hydride generator can deliver 4 mol / L acetic acid and 2% (m / v) KBH4 solution (KBH4 in the figure) to the reaction coil 3, while 1 mL of the sample is delivered to the reaction coil 3 through a specific mobile phase (sodium citrate buffer). The generated volatile antimony is separated from water by the gas-liquid separator 4 and collected with a 500 mL gas bag.

[0038] Among them, in the methylantimony cryogenic trapping device, the U-shaped chromatographic column 9 is connected to the six-port valve 6, and the other inlets of the six-port valve 6 are respectively connected to the dryer 5, the He gas cylinder, the rotameter 8, and the gas chromatography-mass spectrometry system 10. The U-shaped chromatographic column 9 is filled with 10% SP-2100 coated Chromosorb (45 - 60 mesh, Supelco). The gas sample in the gas bag passes through the dryer 5 and then enters the U-shaped chromatographic column 9 through the six-port valve 6. The U-shaped chromatographic column 9 is pre-cooled to -196 °C with liquid nitrogen. Then, a DC switch power supply is connected with a nichrome wire, and the column temperature is heated from -196 °C to 100 °C within 3 minutes, and the gas is blown into the gas chromatography-mass spectrometry system 10 with helium for separation and detection.

[0039] Among them, the gas chromatography-mass spectrometry system 10 uses the six-port valve 6 to switch the purge gas and the carrier gas. The mass range of the gas chromatography-mass spectrometry is selected according to the expected mass of the analyzed compound. The electron ionization (EI) ion source mode is used, and the methylantimony compound is semi-quantified by the selected ion monitoring mode (SIM).

[0040] Example 2: Chromatographic and mass spectrometric identification of three methylantimony forms using the device of the present invention

[0041] The device of Example 1 is used to detect three methylantimony compounds:

[0042] The peristaltic pump 2 in the hydride generator delivers 4 mol / L acetic acid and 2% (m / v) KBH4 solution to the reaction coil 3, while 1 mL of the sample is delivered to the reaction coil 3 through sodium citrate buffer. The generated volatile antimony is separated from water by the gas-liquid separator 4 and collected with a 500 mL gas bag.

[0043] The gas in the gas bag directly enters the U-shaped trap 9, which is pre-cooled to -196 °C with liquid nitrogen. Then, a DC switch power supply is connected with a nichrome wire, and the column temperature is heated from -196 °C to 100 °C within 3 minutes, and the gas is blown into the gas chromatography-mass spectrometry system 10 with helium for separation and detection.

[0044] Table 1 GC-MS operating parameters

[0045]

[0046] The chromatograms and mass spectra of the four antimony compounds, hydrogen antimonide SbH3, methylantimony CH3SbH2, dimethylantimony (CH3)2SbH, and trimethylantimony (CH3)3Sb, finally obtained are as Figure 2 and Figure 3 shown, and four antimony-containing peaks were detected.

[0047] Based on the m / z 123.8 121 SbH3] + and m / z 125.9 123 SbH3] + plasma signals, the first antimony-containing peak (retention time t R = 7.5 minutes) was determined to be SbH3( Figure 3 in Figure a), which is consistent with the product result after hydrogenation of the previous Sb(III) solution. The second antimony-containing peak (t R = 8.2 minutes) was determined to be CH3SbH2( 121 SbH2] + and m / z 139.9[CH3 121 SbH2] + etc. based on the ion signals m / z 137.9[CH3 Figure 3 in Figure b). The mass spectrometry ion signals of the third antimony-containing peak (t R = 8.9 minutes) are m / z 152[(CH3)2 121 SbH] + 、m / z 153.9[(CH3)2 123 SbH] + 、m / z 135.9[CH3 121 Sb] + and m / z 137.9[CH3 123 Sb] + etc.( Figure 3 in Figure c). The fourth antimony-containing peak (t R = 9.6 minutes) can be qualitatively determined as (CH3)3Sb based on the ion signal m / z 165 in its mass spectrum. m / z 165.9[(CH3)3 121 Sb] + ,m / z 168[(CH3)3 123 Sb] + ,m / z 150.9[(CH3)2 121 Sb] +, m / z 152.9 [(CH3)2 123 Sb] + , m / z 135.9 [CH3 121 Sb] + and m / z 137.9 [CH3 123 Sb] + etc. ( Figure 3 in Figure d). In addition, for the other two peaks, Figure 2 in it, peak A is the baseline change after cold trap heating in HG-LT-GC-MS detection, and peak B is the air generated by hydrogenation.

[0048] Example 3. Detection of liquid and gaseous methylantimony species in anaerobic enriched cultures of paddy soil using the device of the present invention

[0049] The device of Example 1 was used to detect the liquid and gaseous methylantimony species in anaerobic enriched cultures of paddy soil. The specific steps were as follows:

[0050] 5 g of fresh paddy soil was added to 10 mL of EA medium (composition of EA medium: 1 / 4 concentration TSB, 5 mM NaNO3, 5 mM Na2SO4, 5 mM ferric citrate, 0.2 g / L yeast extract, and 1 g / L cellobiose, pH 7), and it was statically cultured in a constant temperature incubator at 30 °C. Methane production in the headspace was monitored by gas chromatography - flame ionization detector (GC-FID). After methane production was detected, 1 mL of the culture solution was transferred to 10 mL of fresh sterile EA medium and cultured continuously. This process was repeated three times. When it was considered that there was no soil residue in the culture solution, this enriched culture was used for the antimony methylation experiment.

[0051] The antimony methylation experiment was carried out by adding 20 μM of Sb(III) to the enriched culture. It was cultured for 7 days under the conditions of 30 °C and 160 rpm. The suspension was centrifuged at 14000 × g for 15 minutes, and the supernatant was filtered through a 0.22 μm PES filter for subsequent antimony species analysis.

[0052] The results showed that methylantimony compounds ( Figure 4 and Figure 5 ) were detected in both the supernatant and the gas phase. The main species in the liquid phase were monomethylantimony and dimethylantimony, while the main species in the gas phase were trimethylantimony.

Claims

1. A qualitative and semi - quantitative analysis device for methylantimony in gas and liquid phases, comprising: A gas sample preparation device for converting liquid methylantimony compounds into gaseous methylantimony compounds through a hydride reaction; A methylantimony low - temperature trapping device, consisting of a U - shaped chromatographic column cooled by liquid nitrogen, for trapping and cold focusing of gaseous methylantimony; A gas chromatography - mass spectrometry (GC - MS) system for separation and detection of methylantimony compounds; Wherein, the gaseous methylantimony compounds generated by the gas sample preparation device are input into the methylantimony low - temperature trapping device, and after heating, are input into the GC - MS system for qualitative and semi - quantitative analysis.

2. The qualitative and semi-quantitative analysis device according to claim 1, wherein: The gas sample preparation device includes a continuous - flow hydride generator and a liquid chromatography unit with a quantitative loop; Both the continuous - flow hydride generator and the liquid chromatography unit are connected to a reaction coil, and the other end of the reaction coil is sequentially connected to a gas - liquid separator and a gas bag.

3. The qualitative and semi-quantitative analysis device according to claim 2, characterized in that: The peristaltic pump in the continuous - flow hydride generator transports acetic acid and sodium borohydride or potassium borohydride to the reaction coil; Liquid methylantimony compounds are transported to the reaction coil through the mobile phase.

4. The qualitative and semi-quantitative analysis device according to claim 3, characterized in that: In the methylantimony low - temperature trapping device, the U - shaped trap is filled with 10% SP - 2100 - coated Chromosorb material; The inlet of the U - shaped trap is connected to the gas bag, and the outlet is connected to the GC - MS system.

5. The qualitative and semi - quantitative analysis device according to claim 4, characterized in that: The U - shaped trap is connected to the gas bag and the GC - MS system through a six - way valve.

6. The qualitative and semi - quantitative analysis device according to claim 5, characterized in that: The six - way valve is respectively connected to He gas and a rotameter, and the rotameter is connected to a diaphragm pump.

7. The qualitative and semi-quantitative analysis device according to claim 6, characterized in that: The GC - MS system is connected to the six - way valve to switch the purge gas and the carrier gas to achieve separation and detection of methylantimony compounds.

8. Use of the qualitative and semi - quantitative analysis device according to any one of claims 1 - 7 in realizing qualitative and semi - quantitative analysis of mono - methylantimony, di - methylantimony and tri - methylantimony in gas and liquid phases.

Images