CN106770733A - A kind of method of the polycyclic aromatic hydrocarbon in detection tea oil - Google Patents

Abstract

A method for detecting polycyclic aromatic hydrocarbons in camellia oil, adding magnetic hydroxylated multi-walled carbon nanotubes to the tea oil diluted with n-hexane solvent as a solid-phase extraction agent to adsorb target substances, and performing magnetic separation under the action of an external magnetic field, Collect the solid-phase extraction agent with the target object, remove the supernatant, purify the solid-phase extraction agent with the target object with a purifier, use toluene as a desorbent to desorb the target object on the solid-phase extraction agent, under the action of an external magnetic field Carry out magnetic separation, remove the solid-phase extractant, collect the desorption liquid with the target substance, filter it through an organic filter membrane, and use gas chromatography and mass spectrometry for conventional content determination. The method has the advantages of good selectivity, low detection limit, high sensitivity and high standard recovery.

Description

A method for detecting polycyclic aromatic hydrocarbons in camellia oil

technical field

The invention relates to a method for detecting polycyclic aromatic hydrocarbons in edible oil, in particular to a method for detecting polycyclic aromatic hydrocarbons in camellia oil.

Background technique

Polycyclic aromatic hydrocarbons are lipophilic compounds, and edible oil is the main source of food transmission. Once polycyclic aromatic hydrocarbons enter the human body through the food chain and participate in the metabolism of the body, they are likely to cause toxic and side effects on human fertility, development, internal organs, nervous and immune systems, etc. In a high PAHs environment, it is also easy to induce lung cancer, skin cancer and other cancers. More than 400 carcinogenic PAHs and their derivatives have been discovered so far, and they are the earliest and most numerous carcinogens.

It is well known that high fat content can make the analysis and detection of low concentration residues in edible oil matrix difficult. Due to its high hydrophobicity, PAHs exhibit a strong affinity to oils, and it is for this reason that the extraction of PAHs from edible oils usually requires a lot of manpower and time. At present, there are few pretreatment methods for the detection of PAHs in camellia oil with high nutritional value unique to my country, but the main pretreatment methods for PAHs in olive oil, soybean oil and other edible vegetable oils include liquid-liquid extraction, solid-phase extraction, and solid-phase extraction. Extraction, solid-phase microextraction, gel permeation chromatography, the process of concentrating the extract in the first two methods is more time-consuming; while solid-phase microextraction requires a longer adsorption equilibrium process, and gel permeation chromatography requires more organic solvents, etc., but these traditional pretreatment methods cannot meet the characteristics of simple, rapid, economical and efficient detection of PAHs in camellia oil.

Magnetic hydroxylated multi-walled carbon nanotubes have the advantages of large specific surface area and fast diffusion speed, which make them more and more widely used in the field of food safety detection. Magnetic solid-phase extraction is easy to operate, as long as an external magnetic field is applied to achieve separation, eliminating the more cumbersome steps such as centrifugation and filtration, compared with conventional pretreatment methods, it not only has higher extraction capacity and extraction efficiency for the target , and save time in sample pretreatment.

Contents of the invention

The object of the present invention is to provide a kind of method that detects polycyclic aromatic hydrocarbons in camellia oil, and the technical scheme adopted in the present invention is as follows:

A method for detecting polycyclic aromatic hydrocarbons in camellia oil, comprising the following steps: adding magnetic hydroxylated multi-walled carbon nanotubes to the tea oil diluted with n-hexane solvent as a solid-phase extraction agent to adsorb the target substance, and under the action of an external magnetic field Carry out magnetic separation, collect the solid phase extractant with the target, remove the supernatant, purify the solid phase extractant with the target with a purifier, use toluene as the desorbent to desorb the target on the solid phase extractant, and Magnetic separation is carried out under the action of an external magnetic field, the solid phase extractant is removed, the desorption liquid with the target substance is collected, filtered through an organic filter membrane, and conventional content determination is carried out by gas chromatography and mass spectrometry.

Targets are Chrysene, Benz(a)anthracene, Benzo[b]fluoranthene, Benzo[k]fluoranthene ), benzo[a]pyrene, benzo[ghi]perylene, dibenzo(a,h)anthracene, indeno(1,2, One or more of 3-cd)pyrene (Indeno[1,2,3-cd]pyrene.

A preparation method for magnetically hydroxylated multi-walled carbon nanotubes, comprising the following steps:

(1) Weigh ferric chloride hexahydrate and hydroxylated multi-walled carbon nanotubes and dissolve them in a beaker with ethylene glycol to form a mixed solution A;

(2) Add sodium acetate to the mixed solution A, stir evenly and let it stand at room temperature to obtain the mixed solution B;

(3) Put the mixed solution B into a hydrothermal synthesis reaction kettle whose liner is polytetrafluoroethylene, and react in an oil bath to obtain a synthetic product C;

(4) The synthesized product C was washed sequentially with absolute ethanol and ultrapure water, and then magnetically separated under the action of external magnetism, and the magnetically charged product was dried to obtain magnetic hydroxylated multi-walled carbon nanotubes.

The diameter of the hydroxylated multi-walled carbon nanotubes is 10-110 nm, preferably 50-60 nm.

The amount of the magnetic hydroxylated multi-walled carbon nanotubes used as a solid phase extraction agent is 10-30 mg, preferably 20 mg. When it is preferably 20 mg, the adsorption rate of benzo[b]fluoranthene, benzo[k]fluoranthene, benzopyrene, benzoperylene, indeno(1,2,3-cd)pyrene reaches the maximum, and The adsorption rates of chrysene, benzo[a]anthracene and indeno(1,2,3-cd)pyrene also tended to be stable, and the adsorption rates did not change much with the increase of the amount of solid phase extractant.

The adsorption time of the magnetic hydroxylated multi-walled carbon nanotubes used as the solid phase extractant to adsorb the target substance is 1-5 minutes, preferably 4 minutes. In order to ensure sufficient adsorption, the adsorption process was shaken by an oscillating mixer. The eight kinds of PAH components basically reached adsorption equilibrium in 4 minutes, and all obtained satisfactory recovery rates. Continue to increase the adsorption time, which had little effect on the recovery rate of the target components. On the contrary, some light PAHs and magnetic carbon nano Tubes bind stronger and are more difficult to elute during desorption.

Toluene is used as the desorbent to desorb the target substance on the solid-phase extractant. The desorption time is 1-5min, preferably 2min. In order to ensure sufficient desorption, the desorption process is shaken by an oscillating mixer.

The amount of toluene used as desorbent is 0.5-2.5mL, preferably 1mL.

The detection conditions of gas chromatography are as follows: the chromatographic column is Agilent's DB-5MS chromatographic column, the specification of the chromatographic column is 30m*0.25mm*0.25μm, the carrier gas is helium, the purity of helium is 99.999%, and the flow rate is 1.0mL/ min, the control method of the carrier gas is constant flow, the injection volume is 1.0 μL, the injection method is splitless injection, the inlet temperature is 240-320°C, the column temperature is 100°C, keep for 1min, and the temperature is 30°C/ Min rises to 250°C and keeps for 10 minutes, then rises to 300°C at 30°C/min and keeps for 6 minutes.

Preferably, the temperature of the injection port is 260°C.

The conditions for mass spectrometry detection are as follows: the ion source is electron bombardment ion source (EI); the electron energy is 70 eV; the solvent removal time is 5 min; the ion source temperature is 250 °C; the interface temperature is 280 °C, and the data acquisition mode is ion monitoring (SIM )model.

The present invention has the following significant advantages:

The present invention uses magnetic hydroxylated multi-walled carbon nanotubes as a solid-phase extraction agent to remove Chrysene, Benz(a)anthracene and Benz[b]fluoranthene (Benzo) in tea oil. [b]fluoranthene), benzo[k]fluoranthene (Benzo[k]fluoranthene), benzo[a]pyrene, benzo[ghi]perylene, dibenzo(a,h )Anthracene (Dibenz[a,h]anthracene), indeno(1,2,3-cd)pyrene (Indeno[1,2,3-cd]pyrene) or one or more of them can be detected together, with good selectivity ;

2. Using toluene as a desorbent can desorb 8 kinds of polycyclic aromatic hydrocarbons in camellia oil together, and the desorption rate is high, while other commonly used desorbents such as methanol, acetonitrile, ethyl acetate, methylene chloride, acetone All 8 species cannot be desorbed at the same time, and the desorption rate is low, which affects the test results.

3. Magnetic hydroxylated multi-walled carbon nanotubes have strong extraction ability and can pre-treat larger volume samples, thus achieving a high enrichment factor;

4. Combined with high performance liquid chromatography/mass spectrometry detection for the analysis of various polycyclic aromatic hydrocarbons in camellia oil, the detection limit is low, the sensitivity is high, and the recovery rate of standard addition is high.

5. The application of embodiment 1 in the detection of polycyclic aromatic hydrocarbons in camellia oil by magnetically hydroxylated multi-walled carbon nanotubes not only greatly shortens the time of pre-detection treatment, saves reagents, reduces the harm of organic matter to experimenters in the test, and also Improve the adsorption efficiency and elution efficiency of the target compound. The linear relationship of 8 kinds of polycyclic aromatic hydrocarbons is in the range of 0.01~0.2mg/kg, and the correlation coefficients are all greater than 0.999; At the same level, the average recoveries of the eight targets were 91.5%-97.2%, and the RSDs were 2.2%-6.2%, which fully met the detection requirements of the eight polycyclic aromatic hydrocarbons in camellia oil.

detailed description

In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below. The description in this part is only exemplary and explanatory, and should not have any limiting effect on the protection scope of the present invention.

Example 1

A method for detecting polycyclic aromatic hydrocarbons in camellia oil, comprising the following steps: adding magnetic hydroxylated polycarbonate in the ratio of 50:1 to the mass ratio of camellia oil to magnetic multi-walled carbon nanometers in the tea oil diluted with n-hexane solvent Walled carbon nanotubes are used as a solid-phase extraction agent to adsorb the target, and magnetic separation is performed under the action of an external magnetic field, the solid-phase extraction agent with the target is collected, the supernatant is removed, and n-hexane is used as a purifier to purify the target. Solid-phase extraction agent, use toluene as desorbent to desorb the target on the solid-phase extraction agent, perform magnetic separation under the action of an external magnetic field, remove the solid-phase extraction agent, collect the desorption liquid with the target object, and filter it through a 0.45μm organic filter membrane Afterwards, conventional content determination was performed by gas-liquid chromatography and mass spectrometry.

A preparation method for magnetically hydroxylated multi-walled carbon nanotubes, comprising the following steps:

(1) Weigh 0.60g of ferric chloride hexahydrate, 0.25g of hydroxylated carbon nanotubes (outer diameter 50-60nm, length 10-20μm, purity greater than 95%, specific surface area greater than 40m2/g (Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences) Company)) Dissolve 40mL ethylene glycol in a beaker and configure it as mixed solution A;

(2) Add 2.4g of sodium acetate to the mixed solution A, stir it evenly with a glass rod and let it stand at room temperature for 30 minutes to get the mixed solution B;

(3) Put the mixed solution B into a hydrothermal synthesis reaction kettle with polytetrafluoroethylene liner, and react in an oil bath at 200°C for 15 hours to obtain the synthetic product C;

(4) Rinse the synthetic product C with absolute ethanol and ultrapure water for 3 times, then perform magnetic separation under the action of external magnetism, and dry the magnetic product at 50°C to obtain magnetic hydroxylated multi-walled carbon nanotubes , stored in a vacuum desiccator for later use. The prepared magnetic hydroxylated multi-walled carbon nanotubes have good dispersibility, and the magnetic nanoparticles are evenly decorated on the hydroxylated multi-walled carbon nanotubes, which is beneficial to improving the accuracy of experimental detection.

The diameter of hydroxylated multi-walled carbon nanotubes is 50~60nm.

The amount of magnetic hydroxylated multi-walled carbon nanotubes used as a solid phase extraction agent is 20 mg.

The adsorption time of the magnetic hydroxylated multi-walled carbon nanotubes as the solid phase extraction agent to adsorb the target substance is 4 minutes. In order to ensure sufficient adsorption, the adsorption process was shaken by an oscillating mixer.

Toluene is used as the desorbent to desorb the target substance on the solid phase extractant, and the desorption time is 2 minutes.

The amount of toluene used as desorbent is 1 mL.

The detection conditions of gas chromatography are as follows: the chromatographic column is Agilent's DB-5MS chromatographic column, the specification of the chromatographic column is 30m*0.25mm*0.25μm, the carrier gas is helium, the purity of helium is 99.999%, and the flow rate is 1.0mL/ min, the control method of the carrier gas is constant flow, the injection volume is 1.0 μL, the sampling method is splitless injection, the temperature of the injection port is 280 °C, the temperature of the column is 100 °C, keep for 1 min, and rise at 30 °C/min To 250°C, keep for 10min, then increase to 300°C at 30°C/min, keep for 6min.

The conditions for mass spectrometry detection are as follows: the ion source is electron bombardment ion source (EI); the electron energy is 70 eV; the solvent removal time is 5 min; the ion source temperature is 250 °C; the interface temperature is 280 °C, and the data acquisition mode is ion monitoring (SIM )model.

Example 2

The diameter (nm) of the hydroxylated multi-walled carbon nanotubes is 10-30 or 30-50 or 50-70 or 70-90 or 90-110. Others are the same as in Example 1.

Example 3

The amount (mg) of magnetic hydroxylated multi-walled carbon nanotubes used as a solid phase extraction agent is 10 or 15 or 25 or 30, and the others are the same as in Example 1.

Example 4

The adsorption time (min) of magnetic hydroxylated multi-walled carbon nanotubes as the solid phase extractant to adsorb the target substance is 1 or 2 or 3 or 5, and the others are the same as in Example 1.

Example 5

The desorption time (min) of toluene as the desorbent to desorb the target on the solid-phase extractant is 1 or 3 or 4 or 5, and the others are the same as in Example 1.

Example 6

The amount (mL) of toluene as a desorbent is 0.5 or 1.5 or 2 or 2.5, and the others are the same as in Example 1.

Example 7

The inlet temperature (° C.) is 240 or 280 or 300 or 320, and the others are the same as in Example 1.

Claims (8)

1. it is a kind of detect tea oil in polycyclic aromatic hydrocarbon method, it is characterised in that comprise the following steps：Diluted through n-hexane solvent Magnetic hydroxyl multi-walled carbon nano-tube is added in tea oil afterwards as solid extracting agent adsorbed target thing, under additional magnetic fields Magneto separate is carried out, the solid extracting agent with object is collected, removes supernatant, the solid phase with object is purified with cleanser Extractant, the object on strippant desorption solid extracting agent is made with toluene, and Magneto separate is carried out under additional magnetic fields, is removed Solid extracting agent, collect carry object stripping liquid, through organic membrane filtration after, combined using gas-chromatography, mass spectrum carry out often Rule assay.

2. it is according to claim 1 it is a kind of detect tea oil in polycyclic aromatic hydrocarbon method, it is characterised in that the object It is in the wrong（Chrysene）, benzo [a] anthracene（Benz (a) anthracene), benzo [b] fluoranthene（Benzo[b] fluoranthene）, benzo [k] fluoranthene（Benzo[k]fluoranthene）, BaP（Benzo[a]pyrene）, Ben Bing perylenes （Benzo[ghi]perylene）, dibenzo (a, h) anthracene（Dibenz[a,h]anthracene）, indeno（1,2,3-cd）Pyrene （One or more in Indeno [1,2,3-cd] pyrene.

3. it is according to claim 1 it is a kind of detect tea oil in polycyclic aromatic hydrocarbon method, it is characterised in that the magnetic hydroxyl The preparation method of base multi-walled carbon nano-tube, comprises the following steps：

（1）Weigh ferric chloride hexahydrate, hydroxyl multi-walled carbon nano-tube spent glycol to be dissolved in beaker, be configured to mixed solution A；

（2）Sodium acetate will be added in mixed solution A, stand to obtain mixed solution B after stirring at room temperature；

（3）Mixed solution B is inserted in the hydrothermal synthesis reaction kettle that inner bag is polytetrafluoroethylene (PTFE), being reacted in oil bath must synthesize product Thing C；

（4）Magneto separate is carried out after synthetic product C is rinsed successively with absolute ethyl alcohol and ultra-pure water under additional magnetic action, by band The product of magnetic obtains magnetic hydroxyl multi-walled carbon nano-tube after drying.

4. it is according to claim 1 it is a kind of detect tea oil in polycyclic aromatic hydrocarbon method, it is characterised in that the hydroxylating A diameter of 10-110nm of multi-walled carbon nano-tubes, the magnetic hydroxyl multi-walled carbon nano-tube is as the consumption of solid extracting agent 10-30mg, the magnetic hydroxyl multi-walled carbon nano-tube is 1-5min as the adsorption time of solid extracting agent adsorbed target thing, The desorption time that the toluene makees the object on strippant desorption solid extracting agent is 1-5min, and the toluene makees strippant Consumption is 0.5-2.5mL.

5. it is according to claim 4 it is a kind of detect tea oil in polycyclic aromatic hydrocarbon method, it is characterised in that the hydroxylating A diameter of 50-60nm of multi-walled carbon nano-tubes, the magnetic hydroxyl multi-walled carbon nano-tube is as the consumption of solid extracting agent 20mg, the magnetic hydroxyl multi-walled carbon nano-tube is 4min as the adsorption time of solid extracting agent adsorbed target thing, described The desorption time that toluene makees the object on strippant desorption solid extracting agent is 2min, and the consumption that the toluene makees strippant is 1mL。

6. the method for the polycyclic aromatic hydrocarbon in a kind of detection tea oil according to claim, it is characterised in that the gas phase color The condition for composing detection is as follows：Chromatographic column is the DB-5MS chromatographic columns of Agilent, and the specification of chromatographic column is 30m*0.25mm*0.25 μ M, carrier gas is helium, and the purity of helium is 99.999%, and flow velocity is 1.0mL/min, and the control method of carrier gas is constant current, sample size It is 1.0 μ L, input mode is Splitless injecting samples, and injector temperature is 240-320 DEG C, and column temperature is 100 DEG C, 1min is kept, with 30 DEG C/min rises to 250 DEG C, keeps 10min, then rises to 300 DEG C with 30 DEG C/min again, keeps 6min.

7. it is according to claim 6 it is a kind of detect tea oil in polycyclic aromatic hydrocarbon method, it is characterised in that the injection port Temperature is 260 DEG C.

8. a kind of method for detecting the polycyclic aromatic hydrocarbon in tea oil according to claim 1, it is characterised in that mass spectrum inspection The condition of survey is as follows：Ion gun is electron impact ion source（EI）；Electron energy is 70eV；The solvent mute time is 5min；From Source temperature is 250 DEG C；Interface temperature is 280 DEG C, and the drainage pattern of data is ion monitoring (SIM) pattern.