1. The application of the combination of the magnetic straw biochar and GC/MS in the determination of trace organic phosphorus in a water sample is characterized in that the magnetic straw biochar is prepared by adopting a one-step synthesis method, and the one-step synthesis method comprises the following steps:

step (1), mixing corn stalk and Fe²⁺Salt, containing Fe³⁺Dissolving salt in deionized water to obtain a uniform mixed solution;

the corn straw contains Fe²⁺Fe in salt²⁺Containing Fe³⁺Fe in salt³⁺The feeding ratio of the deionized water to the deionized water is 8-12: 1.2-2.4: 16-32: 30-40, unit is g: mmol: mmol: mL;

adjusting the pH value of the mixed solution to 10-11, stirring for 0.5-1 h, filtering, and drying in an oven at 100-110 ℃ for 2-3 h;

step (3), placing the dried material in a tube furnace, N₂Pyrolyzing for 40-60 min at 400-800 ℃ in the atmosphere to obtain a carbonized material;

and (4) washing the carbonized material with deionized water to be neutral to obtain the magnetic straw biomass charcoal.

2. Use according to claim 1, characterized in that it comprises the following steps:

s1, filtering the water sample to be detected;

s2, adding magnetic straw biomass charcoal into the water sample filtered in the step S1, and oscillating the extracted water sample by using a shaking table to adsorb trace organic phosphorus on the magnetic straw biomass charcoal; separating the magnetic straw biochar adsorbing the trace organic phosphorus from a sample by using the action of an external magnetic field force to obtain the magnetic straw biochar adsorbing the trace organic phosphorus; carrying out vortex oscillation desorption on the magnetic straw biochar adsorbing trace organic phosphorus by using ethyl acetate, and filtering the separated desorption solution;

s3, determining the concentration of organic phosphorus in the desorption solution by GC/MS;

the mass-to-volume ratio of the water sample to be detected to the magnetic corn straw biomass charcoal is 20-40 mL: 15-25 mg.

3. The application of claim 2, wherein the volume ratio of the water sample to be detected to ethyl acetate is 20-40 mL: 200 μ L.

4. Use according to claim 2, characterized in that the shaking table shaking conditions are 200rpm, 25 ℃; vortex oscillation speed 1400 rpm.

5. Use according to claim 1, characterized in that the Fe-containing compound is²⁺The salt being FeCl₂·4H₂O, containing Fe³⁺The salt being FeCl₃·6H₂O; corn stalk, Fe-containing²⁺Fe in salt²⁺Containing Fe³⁺Fe in salt³⁺And the feed ratio of the deionized water is 10: 1.2: 16: 40, unit g: mmol: mmol: and (mL).

6. The application of the combination of the magnetic straw biochar and GC/MS (gas chromatography/mass spectrometry) in the determination of trace organic phosphorus in soil is characterized in that the magnetic straw biochar is prepared by adopting a one-step synthesis method, and the one-step synthesis method comprises the following steps:

step (1), mixing corn stalk and Fe²⁺Salt, containing Fe³⁺Dissolving salt in deionized water to obtain a uniform mixed solution;

the corn straw contains Fe²⁺Fe in salt²⁺Containing Fe³⁺Fe in salt³⁺The feeding ratio of the deionized water to the deionized water is 8-12: 1.2-2.4: 16-32: 30-40, unit is g: mmol: mmol: mL;

adjusting the pH value of the mixed solution to 10-11, stirring for 0.5-1 h, filtering, and drying in an oven at 100-110 ℃ for 2-3 h;

step (3), placing the dried material in a tube furnace, N₂Pyrolyzing for 40-60 min at 400-800 ℃ in the atmosphere to obtain a carbonized material;

and (4) washing the carbonized material with deionized water to be neutral to obtain the magnetic straw biomass charcoal.

7. Use according to claim 1, characterized in that it comprises the following steps:

s1, drying the soil sample to be detected, grinding and sieving;

s2, ultrasonically extracting the soil treated in the step S1 in acetone for 20-40 min, and centrifuging;

s3, taking the supernatant obtained in the step S2, drying the supernatant by using nitrogen, adding chromatographic methanol into the supernatant, and re-dissolving the supernatant to obtain a re-dissolved sample;

s4, mixing the re-dissolved sample, ultrapure water and magnetic corn straw biomass charcoal, and performing shaking extraction by using a shaking table, wherein trace organic phosphorus in soil is adsorbed on the magnetic biomass charcoal; separating the magnetic material adsorbing the trace organic phosphorus from the soil by using the action of an external magnetic field force to obtain the magnetic material adsorbing the trace organic phosphorus; carrying out vortex oscillation desorption on the magnetic material adsorbing trace organic phosphorus by using ethyl acetate, separating desorption liquid from the magnetic material by using a magnet, and filtering the separated desorption liquid;

the feeding ratio of the re-dissolved sample to the magnetic corn straw biomass charcoal is 100-200 mu L: 15-25 mg;

s5, and determining the concentration of organic phosphorus in desorption by GC/MS.

8. The application of claim 7, wherein the feeding ratio of the soil to be detected to ethyl acetate is 1-2 g: 200-400 μ L.

9. Use according to claim 7, characterized in that the shaking table shaking conditions are 200rpm, 25 ℃; vortex oscillation speed 1400 rpm.

10. Use according to claim 1, characterized in that the Fe-containing compound is²⁺The salt being FeCl₂·4H₂O, containing Fe³⁺The salt being FeCl₃·6H₂O; corn stalk, Fe-containing²⁺Fe in salt²⁺Containing Fe³⁺Fe in salt³⁺And the feed ratio of the deionized water is 10: 1.2: 16: 40, unit g: mmol: mmol: and (mL).

Background

In the field of analytical chemistry, trace, ultra trace target analysis in environmental samples has been the focus of attention. Because the sample matrix is complex, the interference is serious, and the concentration of the target object to be detected is low, the target object cannot be directly analyzed by an instrument, and the target object needs to be enriched, separated and then measured through effective sample pretreatment steps. Therefore, sample pretreatment is an extremely important step, determining the sensitivity and stability of the overall assay. Magnetic solid-phase Microextraction (MSPE) takes a Magnetic material as an adsorbent, and after the Magnetic material is dispersed and adsorbs a target object in a sample solution, the Magnetic material can be separated from the sample solution under the action of an external magnet. The method has the advantages of small organic solvent capacity and simple and convenient operation, and is suitable for enrichment and separation of the target object in a large-volume sample solution. In the extraction process, the preparation of the adsorbing material which has high adsorption capacity on a target object and simultaneously eliminates impurity interference is very important, and the sensitivity of the method can be effectively improved.

Biochar is a porous carbon material processed from biomass (agricultural wastes, wood chips, animal wastes, marine algae and the like). About 2.5 hundred million tons of corn straws are produced every year in China, the environment pollution is caused by adopting an incineration method for treatment, and the important significance is realized for changing waste into valuable. The straw biomass can be subjected to anaerobic or oxygen-limited carbonization under a high-temperature condition by adopting a pyrolysis method to prepare biochar, organic components of the biomass are largely decomposed in the pyrolysis process, a pore structure is developed, the carbon content and the aromaticity are increased, and the specific surface area and the pore volume are obviously increased. The biomass carbon has large specific surface area, polar functional groups and aromaticity, so the biomass carbon is mainly widely applied to soil remediation and adsorption and removal of organic matters and heavy metals at present, and the application of the biomass carbon in magnetic solid phase extraction for sample pretreatment needs to be further expanded.

Disclosure of Invention

According to the invention, the biochar is combined with the magnetic nanoparticles, the prepared magnetic straw biochar material is used for analyzing trace organophosphorus pesticides in complex samples, and the enrichment efficiency of target compounds is improved to the greatest extent on the basis of discussing preparation conditions and adsorption mechanisms. The method has the following advantages: firstly, the invention does not need to activate the biomass, and the magnetic biochar is obtained after high-temperature carbonization and magnetization, and the preparation steps are simple; secondly, in order to further improve the enrichment performance of the target object, the adding ratio of the magnetic nano particles in the composite material is reduced as much as possible; thirdly, adopting straws as biomass sources, discussing the influence of different pyrolysis temperatures on the structure, chemical property and extraction effect of the magnetic biochar, and establishing structure-activity relationship among the straws to obtain optimal conditions; and fourthly, under the optimal condition, the method is respectively used for measuring trace organic phosphorus in the environmental water and the soil, and has high enrichment efficiency and high sensitivity.

The magnetic straw biomass charcoal adopted in the invention is prepared by adopting a one-step synthesis method, and the one-step synthesis method comprises the following steps:

step (1), mixing corn stalk and Fe²⁺Salt, containing Fe³⁺Dissolving salt in deionized water to obtain a uniform mixed solution;

the corn straw contains Fe²⁺Fe in salt²⁺Containing Fe³⁺Fe in salt³⁺The feeding ratio of the deionized water to the deionized water is 8-12: 1.2-2.4: 16-32: 30-40, unit is g: mmol: mmol: mL;

preferably, it contains Fe²⁺The salt being FeCl₂·4H₂O, containing Fe³⁺The salt being FeCl₃·6H₂O；

Preferably, the reactant is corn straw or Fe-containing²⁺Fe in salt²⁺Containing Fe³⁺Fe in salt³⁺And the feed ratio of the deionized water is 10: 1.2: 16: 40, unit g: mmol: mmol: and (mL).

And (2) adjusting the pH value of the mixed solution to 10-11, stirring for 0.5-1 h, filtering, and drying in an oven at 100-110 ℃ for 2-3 h.

Preferably, the pH adjusting agent is NaOH;

step (3), placing the dried material in a tube furnace, N₂And pyrolyzing for 40-60 min at 400-800 ℃ in the atmosphere to obtain the carbonized material.

And (4) washing the carbonized material with deionized water to be neutral, and drying to obtain the magnetic straw biomass charcoal.

The magnetic straw biochar material prepared by the method is characterized by a scanning electron microscope, a hysteresis loop and a nitrogen adsorption instrument.

The invention aims to provide an application of the magnetic straw biochar in the determination of trace organic phosphorus in an enrichment and separation water sample by GC/MS (gas chromatography/mass spectrometry), which specifically comprises the following steps:

s1, filtering the water sample to be detected by a 0.45-micrometer filter membrane, and storing at 4 ℃;

s2, adding magnetic straw biomass charcoal into the water sample filtered in the step S1, performing shaking extraction for 15-35 min by adopting a shaking table, and adsorbing trace organic phosphorus in the water sample on the magnetic straw biomass charcoal; separating the magnetic straw biochar adsorbing the trace organic phosphorus from a sample by using the action of an external magnetic field force to obtain the magnetic straw biochar adsorbing the trace organic phosphorus; and (3) carrying out vortex oscillation desorption on the magnetic straw biochar adsorbing trace organic phosphorus for 2-8 min by using ethyl acetate, and filtering the separated desorption solution by using a 0.22-micrometer-hole filter membrane.

And S3, measuring the concentration of organic phosphorus in the desorption solution by using GC/MS.

The mass-to-volume ratio of the water sample to be detected to the magnetic corn straw biomass charcoal is 20-40 mL: 15-25 mg;

preferably, the volume ratio of the water sample to be detected to the ethyl acetate is 20-40 mL: 200 mu L;

preferably, the shaking table shaking conditions are 200rpm, 25 ℃;

preferably, the vortex oscillation speed is 1400 rpm.

The second purpose of the invention is to provide the magnetic straw biochar for enriching and separating trace organic phosphorus in soil, and GC/MS determination, which is characterized by comprising the following steps:

s1, after sampling the soil sample to be detected, placing the soil sample in an oven to be dried at 110 ℃, grinding the soil sample in a mortar, and sieving the ground soil sample by a sieve of 0.45 mm.

S2, ultrasonically extracting the soil treated in the step S1 in acetone for 20-40 min, and centrifuging for 3-6 min.

Preferably, the feeding ratio of the soil to the acetone is 10-20 g: 20-40 mL.

S3, taking the supernatant obtained in the step S2, drying the supernatant by using nitrogen, and adding 1-2 mL of chromatographic methanol for redissolving to obtain a redissolved sample;

s4, mixing the re-dissolved sample, ultrapure water and magnetic corn straw biomass charcoal, and performing shaking extraction for 15-35 min by using a shaking table, wherein trace organic phosphorus in soil is adsorbed on the magnetic biomass charcoal; separating the magnetic material adsorbing the trace organic phosphorus from the soil extracting solution by using the action of an external magnetic field force to obtain the magnetic material adsorbing the trace organic phosphorus; and (3) carrying out vortex oscillation desorption on the magnetic material adsorbing the trace organic phosphorus for 2-8 min by using ethyl acetate, separating desorption liquid from the magnetic material by using a magnet, and filtering the separated desorption liquid by using a 0.22-micrometer-pore filter membrane.

The feeding ratio of the re-dissolved sample, the ultrapure water and the magnetic corn straw biomass charcoal is 100-200 mu L: 20-40 mL: 15-25 mg;

the feeding ratio of the soil to be detected to ethyl acetate is 1-2 g: 200-400 μ L;

s5, and determining the concentration of organic phosphorus in desorption by GC/MS.

The magnetic biochar is used for measuring organophosphorus pesticides in a complex environment sample, and has the advantages of wide linear range, low detection limit, high recovery rate and the like.

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

firstly, the magnetic biochar is prepared by a one-step method, and has simple steps, strong magnetism and good dispersibility;

secondly, the straw biomass is cheap and rich in source, and is combined with a magnetic solid phase extraction technology, and the magnetic biochar serving as an extraction medium has the characteristics of easiness in magnetic separation and suitability for large-volume sample treatment.

And thirdly, on the basis of optimizing the magnetic load capacity and the pyrolysis temperature and establishing a structure-activity relationship between preparation conditions, namely a biochar structure and extraction performance, the optimal magnetic biochar is obtained, trace organic phosphorus in a complex sample can be enriched and separated through pi-pi action, surface adsorption, hydrogen bonds and other actions, the enrichment effect is good, and the optimal magnetic biochar is combined with GC/MS for determination, so that the detection limit is low, and the sensitivity is high.

Drawings

Figure 1 is an optimized graph of magnetic particle loading.

FIG. 2 is the scanning electron microscope images of the straw biochar (A) and the magnetic straw biochar (B).

Fig. 3 is a hysteresis loop of the magnetic biochar, and the inset is a graph of the magnetic separation effect of the magnetic biochar.

FIG. 4 is an infrared spectrum of magnetic straw biomass charcoal prepared at different pyrolysis temperatures.

FIG. 5 is a comparison graph of the extraction effect of magnetic straw biomass charcoal on organophosphorus prepared at different pyrolysis temperatures.

FIG. 6 GC/MS diagram of direct sample injection of organophosphorus mixed standard and enrichment of magnetic straw biomass charcoal (1: fenamiphos, 2: dimethoate, 3: chlorazol phosphorus, 4: ammonium phosphate, 5: pirimiphos-methyl, 6: fenitrothion, 7: chlorpyrifos, 8: parathion, 9: chlorpyrifos, 10: profenofos, 11: ethion, 12: triazophos).

FIG. 7 recycling performance of magnetic biochar.

Detailed Description

The present invention is further analyzed with reference to the following specific examples.

Example 1: preparation of magnetic biochar

Drying 10g of corn straw, crushing by using a high-speed crusher, and mixing with FeCl₂·4H₂O (0.4772g, 2.4mmol) and FeCl₃·6H₂O (8.6496g, 32mmol) was mixed well in 40mL of ionized water and magnetically stirred for 30 min. And dropwise adding 10mol/L NaOH solution until the pH value is 10-11, and continuously stirring for 30 min. Filtering, putting the obtained product into a 110 ℃ oven for 2h, putting the product into a tube furnace, and reacting in a reactor under N₂Raising the temperature to 700 ℃ at a heating rate of 20 ℃/min under the atmosphere, and keeping the temperature for 40 min. Washing the obtained product with deionized water for multiple timesAnd drying the mixture for 6 hours at 110 ℃ until the mixture is neutral to obtain the magnetic biochar.

Example 2: in order to further reduce the magnetic load, 10g of corn straw and FeCl are added₂·4H₂O (0.2386g, 1.2mmol) and FeCl₃·6H₂O (4.324g, 16mmol) was mixed and the other steps were as above.

FIG. 1 is a comparison of the extraction performance of the magnetic biochar prepared in examples 1 and 2. The reduction of the magnetic loading capacity obviously improves the extraction effect of the composite material on the organic phosphorus, and reveals the main function of the straw biochar in the organic phosphorus adsorption; continuing to reduce Fe²⁺、Fe³⁺The dosage is respectively 0.6mmol and 8mmol, and the obtained magnetic biochar has weaker magnetism and cannot meet the requirement of magnetic separation.

Example 3: magnetic biochar was prepared based on example 1 using different pyrolysis temperatures (300, 400, 500, 600, 700, 800 ℃) and the biochar prepared was named MB300, MB400, MB500, MB600, MB700, MB800, respectively. Other conditions were the same as in example 1.

Among them, the magnetic properties of MB300 are weak and cannot meet the requirement of magnetic separation, so they will not be discussed. Table 1 shows the physicochemical properties of the magnetic straw biomass charcoal prepared at a pyrolysis temperature of 400 to 800 ℃. As the temperature increases, the specific surface area and pore volume of the biochar show an increasing tendency.

TABLE 1 specific surface area and pore volume parameters of magnetic straw Biomass charcoal prepared at different pyrolysis temperatures

Biomass charcoal	BET specific surface area (m)2/g)	Total pore volume (cm)3/g)
			MB400	7.1751	0.024483
MB500	9.2781	0.028481
			MB600	164.2298	0.119272
MB700	208.5834	0.162540
			MB800	252.7942	0.251396

Fig. 2 to 3 are a scanning electron micrograph and a hysteresis loop chart of the magnetic straw biochar MCC700 obtained in example 2 of the present invention.

FIG. 2A is a surface topography of the straw biochar; fig. 2B is a composite material of magnetic nanoparticles and straw biochar, from which it can be seen that the magnetic nanoparticles are distributed on the biochar surface. As can be seen from FIG. 3, MB700 has no remanence and remanence, has a saturation magnetization of 38.5emu/g, shows superparamagnetism, and can be used for quickly separating magnetic biochar from a sample solution by using a magnet (see an inset), so that the requirement of magnetic separation can be met.

FIG. 4 is an infrared spectrum of magnetic straw biochar prepared at different pyrolysis temperatures. As can be seen from the figure, the biochar prepared under the condition of 400 ℃ has rich oxygen-containing functional groups, and as the temperature rises, the reactions of deoxidation and dehydrogenation gradually occur, so that the stretching vibration peak of the oxygen-containing groups has obvious weakening tendency and almost disappears.

Example 4: characterization of extraction Performance of magnetic biochar

(1) Comparison of extraction performance of magnetic biochar prepared under different pyrolysis temperatures on organophosphorus

15mg of magnetic material was dispersed in a sample solution (40mL) containing 12 organophosphorus including fenamiphos (Ethoprophos), Dimethoate (Dimethoate), chlorazol phosphorus (Isazofos), ammonium phosphate (Phosphamidon), Pirimiphos-methyl (Pirimiphos-methyl), Fenitrothion (fenthion), Chlorpyrifos (Chlorpyrifos), Parathion (Parathion), methidathion (Medathion), Profenofos (Profenofos), Ethion (Ethion), Triazophos (Triazophos) at a concentration of 2. mu.g/L. Extracting for 35min to make the organic phosphorus adsorbed by the magnetic material, and separating the magnetic material combined with the organic phosphorus from the sample solution under the external magnetic field after the extraction is finished; finally, 200. mu.L of ethyl acetate was added for desorption for 4min, and the desorption solution was measured by GC/MS.

(2) GC/MS determination of organophosphorus conditions and related parameters

The measurement conditions were as follows: sample inlet temperature: 260 ℃; sample introduction volume: 1 mu L of the solution; the ion source temperature is 300 ℃; the energy is 70 eV; the temperature of the transmission line is 280 ℃; helium (purity is more than 99.999%), the flow rate is 1.0mL/min, and split-flow sample injection is not carried out; selecting a reaction monitoring mode (SRM); column temperature programmed heating: the initial temperature is 50 ℃, the temperature is kept for 3min, the temperature is increased to 180 ℃ at the speed of 25 ℃/min, the temperature is increased to 250 ℃ at the speed of 5 ℃/min, the temperature is increased to 300 ℃ at the speed of 35 ℃/min, and the temperature is kept for 2 min. The mass spectrometry conditions are shown in table 1.

Table 212 detection parameters of organic phosphorus

Analyte	Molecular formula	Qualitative ion pair (m/z)	Quantitative ion pair (m/z)	Collision energy (eV)
					Miao ethephon	C8H19O2PS2	158.00/97.00	97.00/65.00	16
Leguo (fruit of musical instruments)	C5H12NO3PS2	125.00/79.00	93.00/63.10	8
					Chlorazol phosphorus	C9H17ClN3O3PS	119.00/76.00	161.10/119.00	6
Ammonium phosphate	C10H19ClNO5P	264.10/127.10	127.10/109.10	10
					Pirimiphos-methyl	C11H20N3O3PS	276.10/151.10	276.10/244.10	6
Fenitrothion	C9H12NO5PS	277.10/109.00	109.10/79.00	6
					Chlorpyrifos	C9H11Cl3NO3PS	196.90/107.00	196.90/168.90	10
Parathion	C10H14NO5PS	139.10/109.10	109.00/81.10	8
					Phoxim-methyl	C6H11N2O4PS3	85.10/58.10	145.00/85.10	6
Profenofos	C11H15BrClO3PS	208.00/144.00	337.00/267.00	10
					Ethos	C9H22O4P2S4	231.00/129.00	153.00/97.00	8
Triazophos	C12H16N3O3PS	161.10/106.10	161.10/134.10	6

(3) The magnetic straw biomass charcoal prepared under different temperature conditions extracts 12 kinds of organic phosphorus, and the extraction effect is shown in figure 5. As can be seen from the figure, in the range of 400-700 ℃, the extraction peak area of the magnetic biochar to most of the organic phosphorus increases along with the increase of the pyrolysis temperature. When the temperature is increased to 600-700 ℃, the hemicellulose and other organic compounds are cracked, so that more pores are generated in the biochar, the specific surface area is increased, and the extraction capacity of organic phosphorus is enhanced; in addition, in the temperature rising process, the carbon content of the biochar is increased, the aromaticity is enhanced, and the carbon content and organic phosphorus are enhanced through the pi-pi effect. However, when the pyrolysis temperature is increased to 800 ℃, the oxygen-containing functional groups on the surface of the biochar are further weakened, so that the hydrogen bonding action between the biochar and a target object is weakened, and the extraction performance is obviously reduced. Therefore, the adsorption of the straw biochar on the organic phosphorus is closely related to the specific surface area, pi-pi effect and hydrogen bond effect of the straw biochar. The optimal pyrolysis conditions were chosen at 700 ℃.

FIG. 6 is a GC/MS diagram of direct sample introduction of an organophosphorus mixed standard (2 mug/L) and after magnetic straw biomass charcoal MSPE, and after extraction, the peak area is obviously improved; the enrichment factor EFs of the magnetic biochar on 12 organophosphorus is 51.8-210.2 (listed in Table 3), and the enrichment performance is high.

The recycling performance of the magnetic biochar is shown in fig. 7, and the result shows that after the magnetic biochar is recycled for 6 times, the material extraction effect is basically stable, the stability is good, and the recycling performance is good. The magnetic property of the material is good, the loss of the magnetic material is not caused in the recovery process, and the stability is good.

TABLE 3 methodological data for determination of 12 organophosphorus by MSPE combined with GC/MS

The results of the methodology prove that the ethoprophos, the ammonium phosphate, the chlorpyrifos, the chlorzofos, the profenofos, the pirimiphos-methyl, the chlorpyrifos and the triazophos have good linear relations in the range of 0.1 to 50.0 mu g/L, the dimethoate, the fenitrothion, the parathion and the ethion have good linear relations in the range of 0.5 to 50.0 mu g/L, and the correlation coefficient R²Are all above 0.99. The detection limit LODs is 0.02-0.19 μ g/L, the Relative Standard Deviation (RSD) of reproducibility is within 7.3%, and the precision is high.

Example 5: determination of trace organic phosphorus in environmental sample

An environmental water sample (the standard concentration of organic phosphorus is 1 mug/L) is filtered by a filter membrane of 0.45 mu m, then 15mg of the magnetic corn straw biomass charcoal in the embodiment 1 is added, extraction is carried out for 35min, and 200 mu L of ethyl acetate is desorbed for 4 min. The 0.22 μm desorption solution is filtered by a pore filter membrane and is tested by GC/MS.

Drying, grinding and sieving a soil sample (with the standard concentration of 0.04 mu g/g), ultrasonically extracting for 30min in 30mL of acetone, centrifuging for 3min, and taking supernatant and drying by nitrogen. Adding 1mL of chromatographic methanol for redissolving, and taking 100 mu L of chromatographic methanol in 40mL of ultrapure water; adding 15mg of the magnetic corn straw biomass charcoal in the embodiment 1, extracting for 35min by adopting shaking table oscillation (200rpm, 25 ℃), adsorbing trace organic phosphorus on the magnetic biomass charcoal, and adsorbing and separating a magnetic material by utilizing the action of an external magnetic field force; carrying out vortex oscillation desorption on 200 mu L of ethyl acetate for 4min at the rotating speed of 1400rpm, separating the desorption solution from the magnetic material by using a magnet, and filtering the separated desorption solution by using a 0.22 mu m pore filter membrane to be detected.

TABLE 3 analysis of organic phosphorus in pond water and soil samples and determination of recovery

Organic phosphorus is not detected in water and soil of the blank pond, and the standard adding recovery rate of the standard adding environmental water and soil samples is measured, so that the result shows that the standard adding recovery rate is more than 73%, the relative standard deviation is lower than 10%, and the recovery rate is higher.

The above embodiments are not intended to limit the present invention, and the present invention is not limited to the above embodiments, and all embodiments are within the scope of the present invention as long as the requirements of the present invention are met.