CN112526010B - Method for detecting short-chain chlorinated paraffin in marine products - Google Patents
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Abstract
The invention discloses a method for detecting short-chain chlorinated paraffin in marine products, which comprises the following steps: (1) sampling and preparing a sample; (2) sampling and accelerating solvent extraction; (3) degreasing and impurity removing; (4) performing headspace solid phase microextraction; (5) detecting by gas chromatography-mass spectrometry; (6) drawing a standard curve; (7) and (4) sample determination. The method optimizes the sample purification treatment process and detection conditions, adopts accelerated solvent extraction, headspace solid-phase microextraction and gas chromatography-mass spectrometry to determine the short-chain chlorinated paraffin in the marine products, has simple operation, does not need additional organic solvent in the purification process, is environment-friendly, meets the requirement of green development, can complete the whole accelerated solvent extraction and headspace solid-phase microextraction process by an instrument, has high automation degree, accurate result, higher sensitivity and satisfactory recovery rate and repeatability, and can be used for determining the content of the short-chain chlorinated paraffin in the marine products.
Description
Technical Field
The invention relates to the technical field of marine product pollution detection, in particular to a method for detecting short-chain chlorinated paraffin in marine products.
Background
Short-chain chlorinated paraffins, i.e. polychlorinated n-alkanes, with a carbon chain length of C 10 -C 13 (chlorine content of 30% -70%), since the 30 s of the 20 th century, it has been widely used in the fields of metal working fluids, flame retardants, plasticizers, paints, leathers and sealants, etc. There is evidence that short chain chlorinated paraffins have been detected in all biospheres including human tissue, which has raised a high degree of scientific interest. Due to chemical stability and high toxicity, which makes it bioaccumulative and bioamplified through food nets, once consumed by humans, poses adverse risks to human health, it has been placed in the stockholm convention to limit the presence of short-chain chlorinated paraffins in other chlorinated paraffin mixtures. The marine product is an important component of protein sources in the diet of residents in coastal areas of China, and the analysis of the content of short-chain chlorinated paraffin in the marine product is important for evaluating the health risk of residents caused by exposure of the short-chain chlorinated paraffin through the marine productThe significance of (1).
At present, the short-chain chlorinated paraffin in a biological sample is detected at home and abroad mainly by extraction technologies such as Soxhlet extraction, accelerated solvent extraction and the like, and by combining one or two purification methods such as concentrated sulfuric acid purification, chromatographic column purification and gel permeation chromatography purification, and then by adopting technologies such as gas chromatography, gas chromatography-mass spectrometry, gas chromatography-tandem mass spectrometry and the like. When concentrated sulfuric acid is adopted for purification, the operation is complicated, the operation needs to be repeated for many times, and further column chromatography purification needs to be carried out; when the column or gel permeation chromatography is used for purification, a large amount of elution solvent (76-200mL) is consumed. Therefore, a green pretreatment method for further purification without additional organic solvent after extraction is developed, and the bottleneck of the prior art is hopefully solved.
Disclosure of Invention
The invention aims to solve the technical problems of the existing short-chain chlorinated paraffin detection method, and provides the detection method of the short-chain chlorinated paraffin in the marine products, which has the advantages of simple operation, no need of using additional organic solvent in the purification process, environmental friendliness, high automation degree, accurate result, higher sensitivity, satisfactory recovery rate and satisfactory reproducibility.
In order to achieve the purpose, the invention adopts the following technical scheme: a method for detecting short-chain chlorinated paraffin in marine products comprises the following steps:
(1) sampling and sample preparation
Mashing marine product sample, homogenizing, freeze drying, refrigerating at-80 deg.C, and testing. Marine products to be detected can be directly collected from the sea or purchased in an aquatic wharf, a supermarket, a farmer market and an aquatic product wholesale market through a fishing boat trawl, and are packaged by clean aluminum foils and sealed in polyethylene bags for transportation.
(2) Sampling and accelerated solvent extraction
Weighing four samples to be detected, wherein each sample is 2.00g, carrying out accelerated solvent extraction on the samples to be detected respectively, and collecting extract liquor, wherein the accelerated solvent extraction comprises the following specific steps: the bottom of a 34mL extraction pool is filled with 3-5g of activated Florisil, 3-5g of activated neutral silica gel and 1g of activated anhydrous sodium sulfate;uniformly mixing a sample to be detected with a proper amount of diatomite, filling the mixture into an extraction tank, and adding 1ng of a substitute internal standard 13 C10-trans-chlordane, filling the top of the extraction tank with a proper amount of diatomite; the solvent extraction was accelerated by using n-hexane and dichloromethane in a volume ratio (v/v) of 1:1 as the extraction agents. The traditional extraction methods such as Soxhlet extraction and the like are time-consuming in extraction process, high in working strength and large in toxic solvent consumption; the accelerated solvent extraction has the advantages of rapidness, batch treatment, less solvent consumption and the like, and the accelerated solvent extraction can remove partial grease, pigment and other interference impurities by filling a proper solid phase adsorbent at the bottom of the extraction tank, so that the purpose of primary purification in the extraction tank is fulfilled.
(3) Degreasing and impurity removal
Respectively placing the extract liquor at-80 deg.C, freezing, defatting, centrifuging and taking supernatant; 3-5g of acidic silica gel (44% sulfuric acid, w/w) was added to the supernatant, vortexed, passed through a column of anhydrous sodium sulfate, evaporated to dryness in a 38 ℃ water bath, and dissolved in 10mL of Milli-Q water (18.2 M.OMEGA./cm) to obtain a solution. The strict pretreatment purification process is the premise of ensuring the accuracy of the detection method, although the preliminary purification is realized in the extraction tank, the extraction liquid also contains more fat and other impurities which can interfere the detection of the short-chain chlorinated paraffin, so that the further degreasing and impurity removal operation is needed; the method adopts the freezing degreasing, the freezing degreasing technology is simple, no extra reagent, gel permeation chromatography and other large-scale instruments are needed, a part of fat can be removed, and then the acidic silica gel is adopted for degreasing, so that the fat and other impurities are further removed, and the powerful guarantee is provided for the subsequent smooth headspace solid phase microextraction.
(4) Headspace solid phase microextraction
Respectively transferring the dissolved solution into a 10mL headspace bottle, adding sodium chloride, immediately sealing by using a headspace bottle cap, dissolving the sodium chloride in a vortex manner, placing a sample on a 32-bit headspace solid phase microextraction automatic sample injector, and performing headspace solid phase microextraction according to preset conditions. Because of its green and environmental friendly, headspace solid-phase microextraction has been rapidly developed in the aspect of organic pollutant detection in environmental water samples in recent years without using organic solvents, but the application in solid samples such as marine products is still rarely reported, generally, marine product muscle tissue is directly added into a headspace bottle for headspace solid-phase microextraction, but the target analyte is not easy to completely volatilize from a solid matrix into a headspace by adopting the method, and the reproducibility and sensitivity are poor.
(5) Gas chromatography-mass spectrometry detection
And inserting the extraction head into a gas chromatography sample injection port, analyzing, detecting according to the set conditions of the gas chromatography-mass spectrometry detector, and injecting the sample four times to obtain a total ion current chromatogram map.
(6) Drawing of standard curve
And (3) characterization: selecting an ion monitoring mode, taking 10 mu L of short-chain chlorinated paraffin standard solution with the total concentration of short-chain chlorinated paraffin monomer of 10 ng/mu L and the chlorine content of 55.5 percent, and adding 1ng of substitute internal standard 13 C10-trans-chlordane, using Milli-Q water to fix the volume to 10.00mL, preparing short-chain chlorinated paraffin standard working solution with the concentration of 10 mug/L and the chlorine content of 55.5%; carrying out four times of sample injection detection on the short-chain chlorinated paraffin standard working solution according to the steps (4) to (5) to obtain a total ion flow diagram chromatogram of the standard working solution; performing qualitative analysis according to the retention time, qualitative ions, quantitative ions and chromatographic peak shape comparison;
quantification: respectively taking 10 mu L of short-chain chlorinated paraffin standard solutions with the total concentration of the short-chain chlorinated paraffin monomer of 10 ng/mu L and the chlorine content of 51.5%, 53.5%, 55.5%, 59.25% and 63%, and adding 1ng of the substituted internal standard 13 C10-trans-chlordane, using Milli-Q water to make volume to 10.00mL, preparing short-chain chlorinated paraffin standard working solution with concentration of 10 mug/L and chlorine content of 51.5%, 53.5%, 55.5%, 59.25% and 63%, carrying out four-time injection detection according to steps (4) to (5), and establishing standard curve between the measured chlorine content and total response factorThe linear regression equation of the standard curve is that y is 35.2x-2053.7, wherein y is a total response factor, x is the measured chlorine content, the correlation coefficient is 0.972, the linear regression equation has a good linear relation, the detection limit of the method is 0.25ng/g, and the requirement of the analysis method is met; the solute in the short-chain chlorinated paraffin standard solution is 24 short-chain chlorinated paraffin monomers, and the solvent is acetone; wherein 24 short-chain chlorinated paraffin monomers are respectively C 10 H 17 Cl 5 、C 10 H 16 Cl 6 、C 10 H 15 Cl 7 、C 10 H 14 Cl 8 、C 10 H 13 Cl 9 、C 10 H 12 Cl 10 、C 11 H 19 Cl 5 、C 11 H 18 Cl 6 、C 11 H 17 Cl 7 、C 11 H 16 Cl 8 、C 11 H 15 Cl 9 、C 11 H 14 Cl 10 、C 12 H 21 Cl 5 、C 12 H 20 Cl 6 、C 12 H 19 Cl 7 、C 12 H 18 Cl 8 、C 12 H 17 Cl 9 、C 12 H 16 Cl 10 、C 13 H 23 Cl 5 、C 13 H 22 Cl 6 、C 13 H 21 Cl 7 、C 13 H 20 Cl 8 、C 13 H 19 Cl 9 、C 13 H 18 Cl 10 。
(7) Sample assay
And (4) comparing the quantitative ion peak area in the total ion current chromatogram obtained in the step (5) with the standard curve obtained in the step (6) after calculation, and finally obtaining the determination concentration of the short-chain chlorinated paraffin in the actual sample through conversion. The method comprises the following steps of measuring concentration of the short-chain chlorinated paraffin in an actual sample, wherein i is 24 short-chain chlorinated paraffin monomers:
the method comprises the following steps of (I) calculating the relative area and the relative total area of each short-chain chlorinated paraffin monomer according to the area of a quantitative ion peak in a total ion current chromatogram, wherein the calculation formula of the relative area is as follows:
the formula for calculating the relative total area is:
(II) calculating according to the relative area to obtain a relative integral signal and a relative total integral signal of each short-chain chlorinated paraffin monomer, wherein the calculation formula of the relative integral signal of each short-chain chlorinated paraffin monomer is as follows:
the formula for calculating the relative total integrated signal is:
(III) calculating according to the relative integral signal and the relative total integral signal of each short-chain chlorinated paraffin monomer to obtain the measured chlorine content, wherein the calculation formula is as follows:
(IV) substituting the measured chlorine content (x) into a standard curve linear regression equation y of 35.2x-2053.7 to calculate y (total response factor), and converting according to the total response factor and the relative total area to obtain the measured concentration of the short-chain chlorinated paraffin in the actual sample, wherein the calculation formula is as follows:
preferably, in the step (1), the freeze drying is to dry the marine product sample in a freeze dryer for 12-24 h; the marine product sample is back muscle of fish, muscle of shrimp and crab or shellfish edible part.
Preferably, the seafood sample is no more than 0.5cm x 0.5 cm.
Preferably, in the step (2), the process parameters for accelerating the solvent extraction are as follows: the extraction temperature is 120-150 ℃, the pressure is 1200-1500psi, the heating time is 5-6min, the static cycle time is 5-10min, the volume of the flushing solvent is 60%, the number of static cycles is 2-3, and the nitrogen purging time is 60-100 s.
Preferably, in the step (2), the activated Florisil has the particle size of 60-100 meshes and is obtained by calcining Florisil in a muffle furnace at 550 ℃ for 12 h; the particle size of the activated neutral silica gel is 40-46 mu m, and the activated neutral silica gel is obtained by calcining the neutral silica gel in a muffle furnace at 550 ℃ for 12 h; the activated anhydrous sodium sulfate was obtained by calcining anhydrous sodium sulfate in a muffle furnace at 650 ℃ for 6 h.
Preferably, in step (3), the acidic silica gel is obtained by thoroughly mixing 100g of activated silica gel and 43mL of concentrated sulfuric acid.
Preferably, in step (4), 2.00g of sodium chloride is added; the headspace solid-phase microextraction adopts a 100-micron polydimethylsiloxane solid-phase microextraction extraction head, and the specific process parameters are as follows: the extraction temperature is 80 ℃, the extraction time is 60min, and the shaking speed is 500 rpm. The invention further optimizes the conditions of headspace solid-phase microextraction, namely selection of solid-phase microextraction head, extraction temperature, extraction time and sodium chloride addition: the inventor compares the extraction effects of 6 solid phase micro-extraction heads such as 100 mu m polydimethylsiloxane, 30 mu m polydimethylsiloxane, 7 mu m polydimethylsiloxane, 85 mu m polyacrylate, 65 mu m polydimethylsiloxane/divinylbenzene, 75 mu m carbon molecular sieve/polydimethylsiloxane and the like, and the result shows that the extraction efficiency of the 100 mu m polydimethylsiloxane extraction head is highest, and the relative total area of the extraction head is 1.2-2.5 times that of other extraction heads, so that the invention selects the 100 mu m polydimethylsiloxane solid phase micro-extraction head; for the selected 100 mu m polydimethylsiloxane solid-phase microextraction extraction head, the extraction effects at the extraction temperature of 40 ℃, 50 ℃, 60 ℃, 70 ℃, 80 ℃ and 90 ℃ are compared, and the result shows that the extraction efficiency is increased along with the increase of the temperature, when the temperature is increased to 80 ℃, the extraction efficiency is highest, the extraction efficiency is slightly reduced when the temperature is further increased, and finally, the extraction temperature is selected to be 80 ℃; comparing the extraction effects of the selected polydimethylsiloxane solid-phase micro-extraction head with the extraction time of 20min, 30min, 40min, 50min, 60min, 70min and 80min at the extraction temperature of 80 ℃, wherein the extraction time of the polydimethylsiloxane solid-phase micro-extraction head is 100 mu m, and the results show that the extraction efficiency is increased along with the increase of the extraction time, and when the extraction time is more than 60min, the extraction efficiency is basically kept unchanged, and finally the extraction time is selected to be 60 min; under the conditions of a selected 100-micron polydimethylsiloxane solid-phase microextraction extraction head, an extraction temperature of 80 ℃ and an extraction time of 60min, the extraction effects of 0g, 1g, 2g, 3g and 4g of sodium chloride are considered, and the results show that the extraction efficiency is increased along with the increase of the sodium chloride, but the extraction efficiency is reduced after the amount of the sodium chloride is more than 2g, and finally 2g of the sodium chloride is selected to be added.
Preferably, in the step (5), the extraction head is subjected to resolution for 2min at 270 ℃; the chromatographic conditions are as follows: the temperature of a sample inlet is 270 ℃; the carrier gas is high-purity helium (v/v, 99.999%) with the flow rate of 1 mL/min; the sample injection mode is non-shunt sample injection, and purging is carried out at 15mL/min after 2 min; the transmission line temperature is 270 ℃.
Preferably, the gas chromatographic column is a DB-5MS capillary gas chromatographic column with the specification of 30m multiplied by 0.25mm multiplied by 0.25 mu m, and the stationary phase is a mixed solution of phenyl and methyl polysiloxane, wherein the mass fraction of the phenyl is 5 percent, and the mass fraction of the methyl polysiloxane is 95 percent; the temperature rising procedure of the gas chromatographic column is as follows: the initial temperature is 100 ℃, the temperature is kept for 1min, the temperature is increased to 160 ℃ at the rate of 30 ℃/min, the temperature is kept for 5min, the temperature is increased to 310 ℃ at the rate of 30 ℃/min, the temperature is kept for 11min, and the total running time is 24 min.
Preferably, the mass spectrometry conditions are: an electron capture negative ion source with the ion source temperature of 150 ℃; methane is used as reaction gas; delaying the solvent for 5 min; selecting ion monitoring, adopting four-time sample injection method (four times for each sample), and sequentially scanning for C chain length 10 、C 11 、C 12 、C 13 The short-chain chlorinated paraffin corresponds to four times of determination analysis of each sample,the first sample introduction represents that the carbon chain length is C 10 The qualitative and quantitative ions corresponding to the first headspace solid phase micro-extraction of the short-chain chlorinated paraffin are injected for the second time, the third time and the fourth time respectively to represent that the carbon chain length of the same sample is C 11 、C 12 、C 13 The second, third and fourth headspace solid phase micro-extraction of the short-chain chlorinated paraffin is carried out to obtain corresponding qualitative and quantitative ions.
Therefore, the invention has the following beneficial effects: optimizes the sample purification treatment process and detection conditions, adopts accelerated solvent extraction, headspace solid phase micro-extraction and gas chromatography-mass spectrometry to determine short-chain chlorinated paraffin in marine products, the method is simple to operate, does not need additional organic solvent in the purification process, is environment-friendly, meets the requirement of green development, can complete the whole processes of solvent extraction acceleration and headspace solid-phase microextraction by an instrument, has high automation degree and accurate result, has the detection limit of 0.25ng/g, the recovery rate of short-chain chlorinated paraffin of 71-120 percent, the relative standard deviation (n ═ 5) of 7.1-14.5 percent, the recovery rate of a substitute internal standard of 70-98 percent and the relative standard deviation of 11.5-14.2 percent, has higher sensitivity and satisfactory recovery rate and repeatability, and can be used for measuring the content of the short-chain chlorinated paraffin in marine products.
Drawings
FIG. 1 is a total ion flow chromatogram of a short-chain chlorinated paraffin standard working solution injected four times.
Detailed Description
The invention is further described with reference to the following figures and detailed description.
The following examples used instrumentation mainly include ASE 350 accelerated solvent extraction instruments manufactured by DIONEX corporation, 7890B/7000C triple quadrupole gas chromatography mass spectrometers manufactured by Agilent technologies, Inc., and CombipAL gas chromatography headspace solid phase microextraction autosampler by CTC Analysis AG of Switzerland.
Example 1
(1) Sampling and sample preparation
Removing scales and skin of Carnis Pseudosciaenae, collecting muscle along the back to obtain sample with size not larger than 0.5cm × 0.5cm × 0.5cm, mashing, homogenizing, drying in freeze drier for 12 hr, refrigerating at-80 deg.C, and testing.
(2) Sampling and accelerated solvent extraction
Weighing four samples to be detected, wherein each sample is 2.00g, carrying out accelerated solvent extraction on the samples to be detected for four times respectively, and collecting extract liquor, wherein the accelerated solvent extraction comprises the following specific steps: the bottom of a 34mL extraction cell is filled with activated 3g of Florisil, activated 5g of neutral silica gel and activated 1g of anhydrous sodium sulfate; uniformly mixing a sample to be detected with a proper amount of diatomite, then filling the mixture into an extraction tank, and adding 1ng of a substitute internal standard 13 C10-trans-chlordane, filling the top of the extraction tank with a proper amount of diatomite; n-hexane and dichloromethane in a volume ratio (v/v) of 1:1 are used as extracting agents to carry out accelerated solvent extraction, and the technological parameters of the accelerated solvent extraction are as follows: the extraction temperature is 120 ℃, the pressure is 1500psi, the heating time is 5min, the static cycle time is 5min, the volume of the flushing solvent is 60%, the static cycle times are 2 times, and the nitrogen purging time is 60 s; wherein the particle size of the activated Florisil is 60-100 meshes, and the activated Florisil is obtained by calcining Florisil in a muffle furnace at 550 ℃ for 12 h; the particle size of the activated neutral silica gel is 40-46 mu m, and the activated neutral silica gel is obtained by calcining the neutral silica gel in a muffle furnace at 550 ℃ for 12 h; the activated anhydrous sodium sulfate was obtained by calcining anhydrous sodium sulfate in a muffle furnace at 650 ℃ for 6 h.
(3) Degreasing and impurity removal
Respectively placing the extractive solutions at-80 deg.C for freezing and degreasing for 2h, and centrifuging at 6000r/m for 5min to obtain supernatant; 3g of acidic silica gel (44% sulfuric acid, w/w) was added to the supernatant, vortexed for 3min, passed through a column of anhydrous sodium sulfate, evaporated to dryness in a 38 ℃ water bath, and dissolved in 10mL of Milli-Q water (18.2 M.OMEGA.cm) to obtain a solution, wherein the acidic silica gel was obtained by thoroughly mixing 100g of activated silica gel and 43mL of concentrated sulfuric acid.
(4) Headspace solid phase microextraction
Respectively transferring the dissolved solution into a 10mL headspace bottle, adding 2.00g of sodium chloride, immediately sealing by using a headspace bottle cap, carrying out headspace solid-phase microextraction on a 32-bit headspace solid-phase microextraction automatic sample injector according to a preset condition after the sodium chloride is dissolved in a vortex mode, wherein the headspace solid-phase microextraction adopts a 100-micron polydimethylsiloxane solid-phase microextraction extraction head, and the specific process parameters are as follows: the extraction temperature is 80 ℃, the extraction time is 60min, and the shaking speed is 500 rpm.
(5) Gas chromatography-mass spectrometry detection
After extraction is finished, inserting an extraction head into a gas chromatography sample inlet, performing analysis for 2min at 270 ℃, detecting according to the set conditions of a gas chromatography-mass spectrometer, and performing sample introduction for four times to obtain a total ion chromatogram; the chromatographic conditions are as follows: the temperature of a sample inlet is 270 ℃; the carrier gas is high-purity helium (v/v, 99.999%) with the flow rate of 1 mL/min; the sample injection mode is non-flow-dividing sample injection, and purging is carried out at 15mL/min after 2 min; the transmission line temperature is 270 ℃; the gas chromatographic column adopts a DB-5MS capillary gas chromatographic column with the specification of 30m multiplied by 0.25mm multiplied by 0.25 mu m, and the stationary phase is a mixed solution of phenyl and methyl polysiloxane, wherein the mass fraction of the phenyl is 5 percent, and the mass fraction of the methyl polysiloxane is 95 percent; the temperature rising procedure of the gas chromatographic column is as follows: the initial temperature is 100 ℃, the temperature is kept for 1min, the temperature is increased to 160 ℃ at the rate of 30 ℃/min, the temperature is kept for 5min, the temperature is increased to 310 ℃ at the rate of 30 ℃/min, the temperature is kept for 11min, and the total running time is 24 min.
The mass spectrum conditions are as follows: an electron capture negative ion source with the ion source temperature of 150 ℃; methane is reaction gas; delaying the solvent for 5 min; selecting ions for monitoring, adopting four-time sampling method, and sequentially scanning carbon chain length C 10 、C 11 、C 12 、C 13 The short-chain chlorinated paraffin corresponds to four times of determination and analysis of each sample one by one, and the first sample introduction represents that the carbon chain length is C 10 The qualitative and quantitative ions corresponding to the first headspace solid phase micro-extraction of the short-chain chlorinated paraffin are injected for the second time, the third time and the fourth time respectively to represent that the carbon chain length of the same sample is C 11 、C 12 、C 13 The qualitative and quantitative ions corresponding to the second, third and fourth headspace solid-phase micro-extraction of the short-chain chlorinated paraffin. The retention time, the quantitative ions and the qualitative ions of the 24 short-chain chlorinated paraffin monomers and the substituted internal standard are shown in the table 1.
TABLE 124 Retention time, quantitative ion, qualitative ion for short-chain chlorinated paraffin monomer and alternative internal standard
(6) Drawing of standard curve
And (3) characterization: selecting an ion monitoring mode, taking 10 mu L of short-chain chlorinated paraffin standard solution with the total concentration of short-chain chlorinated paraffin monomers of 10 ng/mu L and the chlorine content of 55.5%, and adding 1ng of substitute internal standard 13 C10-trans-chlordane, using Milli-Q water to fix the volume to 10.00mL, preparing short-chain chlorinated paraffin standard working solution with the concentration of 10 mug/L and the chlorine content of 55.5%; carrying out four times of sample injection detection on the short-chain chlorinated paraffin standard working solution according to the steps (4) to (5) to obtain a total ion flow diagram chromatogram (shown in figure 1) of the standard working solution; performing qualitative analysis according to the retention time, qualitative ions, quantitative ions and chromatographic peak shape comparison;
quantification: respectively taking 10 mu L of short-chain chlorinated paraffin standard solutions with the total concentration of the short-chain chlorinated paraffin monomer of 10 ng/mu L and the chlorine content of 51.5%, 53.5%, 55.5%, 59.25% and 63%, and adding 1ng of the substituted internal standard 13 C10-trans-chlordane, using Milli-Q water to fix the volume to 10.00mL, preparing short-chain chlorinated paraffin standard working solution with the concentration of 10 mug/L and the chlorine content of 51.5%, 53.5%, 55.5%, 59.25% and 63%, carrying out four-time sample injection detection according to the steps (4) to (5), establishing a standard curve between the measured chlorine content and a total response factor, wherein a linear regression equation of the standard curve is that y is 35.2x-2053.7, in the equation, y is the total response factor, x is the measured chlorine content, a correlation coefficient is 0.972, having good linear relation, and the method detection limit is 0.25ng/g, thereby meeting the requirements of an analysis method; the solute in the short-chain chlorinated paraffin standard solution is 24 short-chain chlorinated paraffin monomers, and the solvent is acetone; wherein 24 short-chain chlorinated paraffin monomers are respectively C 10 H 17 Cl 5 、C 10 H 16 Cl 6 、C 10 H 15 Cl 7 、C 10 H 14 Cl 8 、C 10 H 13 Cl 9 、C 10 H 12 Cl 10 、C 11 H 19 Cl 5 、C 11 H 18 Cl 6 、C 11 H 17 Cl 7 、C 11 H 16 Cl 8 、C 11 H 15 Cl 9 、C 11 H 14 Cl 10 、C 12 H 21 Cl 5 、C 12 H 20 Cl 6 、C 12 H 19 Cl 7 、C 12 H 18 Cl 8 、C 12 H 17 Cl 9 、C 12 H 16 Cl 10 、C 13 H 23 Cl 5 、C 13 H 22 Cl 6 、C 13 H 21 Cl 7 、C 13 H 20 Cl 8 、C 13 H 19 Cl 9 、C 13 H 18 Cl 10 ；
(7) Sample assay
And (4) comparing the quantitative ion peak area in the total ion current chromatogram obtained in the step (5) with the standard curve obtained in the step (6) after calculation, and finally obtaining the determination concentration of the short-chain chlorinated paraffin in the actual sample through conversion.
And (3) determining the recovery rate: taking 2.00g of a sample to be detected, respectively adding 2 muL, 10 muL and 100 muL of short-chain chlorinated paraffin standard solution with the concentration of 10 ng/muL and the chlorine content of 55.5 percent, preparing three standard adding samples with low (10ng/g), medium (50ng/g) and high (500ng/g) adding concentration levels, uniformly mixing in a vortex manner, respectively carrying out five times of parallel operation according to the requirements of the steps (2) - (5), comparing with the obtained standard curve, and finally obtaining the measured concentration of the short-chain chlorinated paraffin in the standard adding sample through conversion; the recovery was calculated according to the following formula:
in the formula: r-recovery,%;
C s short chain Chlorination in tagged samplesMeasured concentration of wax, ng/g;
C 0 -concentration of short chain chlorinated paraffin in the actual sample, ng/g;
c is the theoretical standard adding concentration of the short-chain chlorinated paraffin in the standard adding sample, ng/g;
in addition, when each sample is measured, a substitute internal standard is added, and the recovery rate calculation formula of each sample substitute internal standard is as follows:
through detection, the concentration of short-chain chlorinated paraffin in the small yellow croaker is 398.18ng/g, the standard recovery rates of the three additive concentration levels of medium-low (10ng/g), medium (50ng/g) and high (500ng/g) in the standard-added small yellow croaker are respectively 115%, 73% and 85%, the relative standard deviations are respectively 14.2%, 7.1% and 9.6%, the range of the recovery rate of the substitute internal standard is 71% -90%, and the relative standard deviation is 11.5%, so that the requirements of an analysis method on the recovery rate and the reproducibility are met.
Example 2
(1) Sampling and sample preparation
Removing head, shell and appendage of Portunus trituberculatus, collecting muscle to obtain sample with sample size not larger than 0.5cm × 0.5cm × 0.5cm, mashing, homogenizing, drying in freeze drier for 24 hr, refrigerating at-80 deg.C, and testing.
(2) Sampling and accelerated solvent extraction
Weighing four samples to be detected, wherein each sample is 2.00g, respectively carrying out accelerated solvent extraction on the samples to be detected and collecting extract liquor, and the concrete steps of the accelerated solvent extraction are as follows: the bottom of a 34mL extraction cell is filled with activated 5g of Florisil, activated 3g of neutral silica gel and activated 1g of anhydrous sodium sulfate; uniformly mixing a sample to be detected with a proper amount of diatomite, filling the mixture into an extraction tank, and adding 1ng of a substitute internal standard 13 C10-trans-chlordane, filling the top of the extraction tank with a proper amount of diatomite; n-hexane and dichloromethane in a volume ratio (v/v) of 1:1 are used as extracting agents to carry out accelerated solvent extraction, and the technological parameters of the accelerated solvent extraction are as follows: extracting at 120 deg.C under 1500psi for 5min, static circulation for 5min, washing with 60% solvent, and standingThe number of state circulation is 2, and the nitrogen purging time is 60 s; wherein the particle size of the activated Florisil is 60-100 meshes, and the activated Florisil is obtained by calcining Florisil in a muffle furnace at 550 ℃ for 12 h; the particle size of the activated neutral silica gel is 40-46 mu m, and the activated neutral silica gel is obtained by calcining the neutral silica gel in a muffle furnace at 550 ℃ for 12 h; the activated anhydrous sodium sulfate is obtained by calcining anhydrous sodium sulfate in a muffle furnace at 650 ℃ for 6 h.
(3) Degreasing and impurity removal
Respectively placing the extractive solutions at-80 deg.C, freezing, defatting for 2 hr, and centrifuging at 6000r/m for 5min to obtain supernatant; 5g of acidic silica gel (44% sulfuric acid, w/w) was added to the supernatant, vortexed for 5min, passed through a column of anhydrous sodium sulfate, evaporated to dryness in a 38 ℃ water bath, and dissolved in 10mL of Milli-Q water (18.2 M.OMEGA.cm) to obtain a solution, wherein the acidic silica gel was obtained by thoroughly mixing 100g of activated silica gel and 43mL of concentrated sulfuric acid.
(4) Headspace solid phase microextraction
Respectively transferring the dissolved solution into a 10mL headspace bottle, adding 2.00g of sodium chloride, immediately sealing by using a headspace bottle cap, carrying out headspace solid-phase microextraction on a 32-bit headspace solid-phase microextraction automatic sample injector according to a preset condition after the sodium chloride is dissolved in a vortex mode, wherein the headspace solid-phase microextraction adopts a 100-micron polydimethylsiloxane solid-phase microextraction extraction head, and the specific process parameters are as follows: the extraction temperature is 80 ℃, the extraction time is 60min, and the shaking speed is 500 rpm.
(5) Gas chromatography-mass spectrometry detection
After extraction is finished, inserting an extraction head into a gas chromatography sample inlet, performing analysis at 270 ℃ for 2min, detecting according to the set conditions of a gas chromatography-mass spectrometer, and performing sample introduction for four times to obtain a total ion chromatogram; the chromatographic conditions are as follows: the temperature of a sample inlet is 270 ℃; the carrier gas is high-purity helium (v/v, 99.999%) with the flow rate of 1 mL/min; the sample injection mode is non-shunt sample injection, and purging is carried out at 15mL/min after 2 min; the transmission line temperature is 270 ℃; the gas chromatographic column adopts a DB-5MS capillary gas chromatographic column with the specification of 30m multiplied by 0.25mm multiplied by 0.25 mu m, and the stationary phase is a mixed solution of phenyl and methyl polysiloxane, wherein the mass fraction of the phenyl is 5 percent, and the mass fraction of the methyl polysiloxane is 95 percent; the temperature program of the gas chromatographic column is as follows: initial temperature 100 ℃ for 1min, heating to 160 ℃ at a speed of 30 ℃/min, keeping for 5min, heating to 310 ℃ at a speed of 30 ℃/min, keeping for 11min, and keeping the total operation time for 24 min. The mass spectrum conditions are as follows: an electron capture negative ion source with the ion source temperature of 150 ℃; methane is reaction gas; delaying the solvent for 5 min; selecting ions for monitoring, adopting four-time sampling method, and sequentially scanning carbon chain length C 10 、C 11 、C 12 、C 13 The short-chain chlorinated paraffin is in one-to-one correspondence with four determination analyses of each sample, and the first sample introduction represents that the carbon chain length is C 10 The qualitative and quantitative ions corresponding to the first headspace solid phase micro-extraction of the short-chain chlorinated paraffin are injected for the second time, the third time and the fourth time respectively to represent that the carbon chain length of the same sample is C 11 、C 12 、C 13 The second, third and fourth headspace solid phase micro-extraction of the short-chain chlorinated paraffin is carried out to obtain corresponding qualitative and quantitative ions. The retention time, the quantitative ions and the qualitative ions of the 24 short-chain chlorinated paraffin monomers and the substituted internal standard are shown in the table 1.
(6) Drawing of standard curve
The standard curve is plotted as in example 1, and thus is not repeated.
(7) Sample assay
And (4) comparing the quantitative ion peak area in the total ion current chromatogram obtained in the step (5) with the standard curve obtained in the step (6) after calculation, and finally obtaining the determination concentration of the short-chain chlorinated paraffin in the actual sample through conversion.
And (3) determining the recovery rate: and (3) taking 2.00g of a sample to be detected, respectively adding 2 muL, 10 muL and 100 muL of short-chain chlorinated paraffin standard solution with the concentration of 10 ng/muL and the chlorine content of 55.5 percent into the sample to be detected to prepare low (10ng/g), medium (50ng/g) and high (500ng/g) standard adding samples with the concentration levels, uniformly mixing the samples by vortex, respectively carrying out five times of parallel operations according to the requirements of the steps (2) to (5), comparing the operation results with the obtained standard curve, finally obtaining the measured concentration of the short-chain chlorinated paraffin in the standard adding samples by conversion, and calculating the recovery rate by the same method as the example 1.
Through detection, the concentration of short-chain sodium chloride in the blue crabs is 495.30ng/g, the adding standard recovery rates of the low (10ng/g), medium (50ng/g) and high (500ng/g) adding concentration levels of blue crabs are 117%, 76% and 92% respectively, the relative standard deviations are 13.5%, 8.0% and 12.3% respectively, the range of the recovery rate of the substitute internal standard is 71% -92%, and the relative standard deviation is 13.9%, so that the requirements of an analysis method on the recovery rate and the reproducibility are met.
Example 3
(1) Sampling and sample preparation
Removing shell of Sinonovacula constricta Lamarck, taking the edible part to obtain a sample, wherein the sample is not more than 0.5cm multiplied by 0.5cm, mashing, homogenizing, drying in a freeze dryer for 18h, refrigerating at-80 ℃, and detecting.
(2) Sampling and accelerated solvent extraction
Weighing four samples to be detected, wherein each sample is 2.00g, respectively carrying out accelerated solvent extraction on the samples to be detected and collecting extract liquor, and the concrete steps of the accelerated solvent extraction are as follows: the bottom of a 34mL extraction cell is filled with activated 4g of Florisil, activated 4g of neutral silica gel and activated 1g of anhydrous sodium sulfate; uniformly mixing a sample to be detected with a proper amount of diatomite, then filling the mixture into an extraction tank, and adding 1ng of a substitute internal standard 13 C10-trans-chlordane, filling the top of the extraction tank with a proper amount of diatomite; n-hexane and dichloromethane in a volume ratio (v/v) of 1:1 are used as extracting agents to carry out accelerated solvent extraction, and the technological parameters of the accelerated solvent extraction are as follows: the extraction temperature is 120 ℃, the pressure is 1500psi, the heating time is 5min, the static cycle time is 5min, the volume of the flushing solvent is 60%, the static cycle time is 2 times, and the nitrogen purging time is 60 s; wherein the particle size of the activated Florisil is 60-100 meshes, and the activated Florisil is obtained by calcining Florisil in a muffle furnace at 550 ℃ for 12 h; the particle size of the activated neutral silica gel is 40-46 mu m, and the activated neutral silica gel is obtained by calcining the neutral silica gel in a muffle furnace at 550 ℃ for 12 h; the activated anhydrous sodium sulfate is obtained by calcining anhydrous sodium sulfate in a muffle furnace at 650 ℃ for 6 h.
(3) Degreasing and impurity removal
Respectively placing the extractive solutions at-80 deg.C, freezing, defatting for 2 hr, and centrifuging at 6000r/m for 5min to obtain supernatant; 4g of acidic silica gel (44% sulfuric acid, w/w) was added to the supernatant, vortexed for 4min, passed through a column of anhydrous sodium sulfate, evaporated to dryness in a 38 ℃ water bath, and dissolved in 10mL of Milli-Q water (18.2 M.OMEGA.cm) to obtain a solution, wherein the acidic silica gel was obtained by thoroughly mixing 100g of activated silica gel and 43mL of concentrated sulfuric acid.
(4) Headspace solid phase microextraction
Respectively transferring the dissolved solution into a 10mL headspace bottle, adding 2.00g of sodium chloride, immediately sealing by using a headspace bottle cap, after the sodium chloride is dissolved in a vortex manner, placing a sample on a 32-bit headspace solid-phase microextraction automatic sample feeder, carrying out headspace solid-phase microextraction according to a preset condition, wherein a 100-micrometer polydimethylsiloxane solid-phase microextraction extraction head is adopted for headspace solid-phase microextraction, and the specific technological parameters are as follows: the extraction temperature is 80 ℃, the extraction time is 60min, and the shaking speed is 500 rpm.
(5) Gas chromatography-mass spectrometry detection
After extraction is finished, inserting an extraction head into a gas chromatography sample inlet, performing analysis at 270 ℃ for 2min, detecting according to the set conditions of a gas chromatography-mass spectrometer, and performing sample introduction for four times to obtain a total ion chromatogram; the chromatographic conditions are as follows: the temperature of a sample inlet is 270 ℃; the carrier gas is high-purity helium (v/v, 99.999%) with the flow rate of 1 mL/min; the sample injection mode is non-flow-dividing sample injection, and purging is carried out at 15mL/min after 2 min; the transmission line temperature is 270 ℃; the gas chromatographic column is a DB-5MS capillary gas chromatographic column with the specification of 30m multiplied by 0.25mm multiplied by 0.25 mu m, the stationary phase is a mixed solution of phenyl and methyl polysiloxane, wherein the mass fraction of the phenyl is 5 percent, and the mass fraction of the methyl polysiloxane is 95 percent; the temperature rising procedure of the gas chromatographic column is as follows: the initial temperature is 100 ℃, the temperature is kept for 1min, the temperature is increased to 160 ℃ at the rate of 30 ℃/min, the temperature is kept for 5min, the temperature is increased to 310 ℃ at the rate of 30 ℃/min, the temperature is kept for 11min, and the total running time is 24 min.
The mass spectrum conditions are as follows: an electron capture negative ion source with the ion source temperature of 150 ℃; methane is reaction gas; delaying the solvent for 5 min; selecting ions for monitoring, and sequentially scanning carbon chain length C by four-time sampling method 10 、C 11 、C 12 、C 13 The short-chain chlorinated paraffin corresponds to four times of determination and analysis of each sample one by one, and the first sample introduction represents that the carbon chain length is C 10 The first headspace solid phase micro-extraction of the short-chain chlorinated paraffin corresponds to qualitative and quantitative ions, and the second, third and fourth sample injections respectively represent the sameOne sample has a carbon chain length of C 11 、C 12 、C 13 The qualitative and quantitative ions corresponding to the second, third and fourth headspace solid-phase micro-extraction of the short-chain chlorinated paraffin. The retention time, the quantitative ions and the qualitative ions of the 24 short-chain chlorinated paraffin monomers and the substituted internal standard are shown in the table 1.
(6) Drawing of standard curve
The standard curve is plotted as in example 1, and thus is not repeated.
(7) Sample assay
And (4) comparing the quantitative ion peak area in the total ion current chromatogram obtained in the step (5) with the standard curve obtained in the step (6) after calculation, and finally obtaining the determination concentration of the short-chain chlorinated paraffin in the actual sample through conversion.
And (3) recovery rate determination: and (3) taking 2.00g of a sample to be detected, respectively adding 2 muL, 10 muL and 100 muL of short-chain chlorinated paraffin standard solution with the concentration of 10 ng/muL and the chlorine content of 55.5 percent into the sample to be detected to prepare low (10ng/g), medium (50ng/g) and high (500ng/g) standard adding samples with the concentration levels, uniformly mixing the samples by vortex, respectively carrying out five times of parallel operations according to the requirements of the steps (2) to (5), comparing the operation results with the obtained standard curve, finally obtaining the measured concentration of the short-chain chlorinated paraffin in the standard adding samples by conversion, and calculating the recovery rate by the same method as the example 1.
Through detection, the concentration of short-chain sodium chloride in the sinonovacula constricta is 671.40ng/g, the standard recovery rates of the three adding concentration levels of low (10ng/g), medium (50ng/g) and high (500ng/g) in the sinonovacula constricta are respectively 120%, 86% and 71%, the relative standard deviations are respectively 14.5%, 9.6% and 10.2%, the recovery range of the substituted internal standard is 70% -98%, and the relative standard deviation is 14.2%, so that the requirements of an analysis method on the recovery rate and the reproducibility are met.
The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.
Claims (5)
1. A method for detecting short-chain chlorinated paraffin in marine products is characterized by comprising the following steps:
(1) sampling and sample preparation
Mashing marine product sample, homogenizing, freeze drying, refrigerating at-80 deg.C, and testing;
(2) sampling and accelerated solvent extraction
Weighing four samples to be detected, wherein each sample is 2.00g, respectively carrying out accelerated solvent extraction on the samples to be detected and collecting extract liquor, and the concrete steps of the accelerated solvent extraction are as follows: filling activated 3-5g of Florisil, activated 3-5g of neutral silica gel and activated 1g of anhydrous sodium sulfate at the bottom of a 34mL extraction pool; uniformly mixing a sample to be detected with a proper amount of diatomite, then filling the mixture into an extraction tank, and adding 1ng of a substitute internal standard 13 C 10 -trans-chlordane, filling the top of the extraction tank with a suitable amount of diatomaceous earth; in a volume ratio (v/v) of 1:1, taking normal hexane and dichloromethane as extracting agents to accelerate solvent extraction; the technological parameters for accelerating the solvent extraction are as follows: the extraction temperature is 120-150 ℃, the pressure is 1200-1500psi, the heating time is 5-6min, the static cycle time is 5-10min, the volume of the flushing solvent is 60%, the static cycle time is 2-3 times, and the nitrogen purging time is 60-100 s;
(3) degreasing and impurity removal
Respectively placing the extract liquor at-80 deg.C, freezing, defatting, centrifuging and taking supernatant; adding 3-5g of acidic silica gel containing 44 wt% of sulfuric acid into the supernatant, carrying out vortex, passing through an anhydrous sodium sulfate column, carrying out rotary evaporation in a water bath at 38 ℃ to obtain a solution, and adding 10mL of Milli-Q water with the resistivity of 18.2M omega/cm for dissolving to obtain a dissolved solution;
(4) headspace solid phase microextraction
Respectively transferring the dissolved solution into 10mL headspace bottles, adding 2.00g of sodium chloride, immediately sealing by using headspace bottle caps, carrying out vortex dissolution of the sodium chloride, placing the samples on a 32-bit headspace solid-phase microextraction automatic sample feeder, and respectively carrying out headspace solid-phase microextraction according to preset conditions; the headspace solid-phase microextraction adopts a 100-micron polydimethylsiloxane solid-phase microextraction extraction head, and the specific process parameters are as follows: the extraction temperature is 80 ℃, the extraction time is 60min, and the shaking speed is 500 rpm;
(5) gas chromatography-mass spectrometry detection
Inserting the extraction head into a gas chromatography sample inlet, analyzing for 2min at 270 ℃, detecting according to the set conditions of a gas chromatography-mass spectrometry detector after analysis, and carrying out sample injection for four times to obtain a total ion chromatogram;
the chromatographic conditions are as follows: the temperature of a sample inlet is 270 ℃; the carrier gas is high-purity helium with the purity of 99.999 percent (v/v), and the flow rate is 1 mL/min; the sample injection mode is non-flow-dividing sample injection, and purging is carried out at 15mL/min after 2 min; the transmission line temperature is 270 ℃; the gas chromatographic column adopts a DB-5MS capillary gas chromatographic column with the specification of 30m multiplied by 0.25mm multiplied by 0.25 mu m, and the stationary phase is a mixed solution of phenyl and methyl polysiloxane, wherein the mass fraction of the phenyl is 5 percent, and the mass fraction of the methyl polysiloxane is 95 percent; the temperature rising procedure of the gas chromatographic column is as follows: the initial temperature is 100 ℃, the temperature is kept for 1min, the temperature is increased to 160 ℃ at the rate of 30 ℃/min, the temperature is kept for 5min, the temperature is increased to 310 ℃ at the rate of 30 ℃/min, the temperature is kept for 11min, and the total running time is 24 min;
the mass spectrum conditions are as follows: an electron capture negative ion source with the ion source temperature of 150 ℃; methane is reaction gas; delaying the solvent for 5 min; selecting ions for monitoring, adopting four-time sampling method, and sequentially scanning carbon chain length C 10 、C 11、 C 12、 C 13 The short-chain chlorinated paraffin corresponds to four times of determination and analysis of each sample one by one, and the first sample introduction represents that the carbon chain length is C 10 The qualitative and quantitative ions corresponding to the first headspace solid phase micro-extraction of the short-chain chlorinated paraffin are injected for the second time, the third time and the fourth time respectively to represent that the carbon chain length of the same sample is C 11、 C 12、 C 13 The second, third and fourth headspace solid phase micro-extraction of the short-chain chlorinated paraffin is carried out to obtain corresponding qualitative and quantitative ions;
(6) drawing of standard curve
And (3) characterization: selecting an ion monitoring mode, taking 10 mu L of short-chain chlorinated paraffin standard solution with the total concentration of short-chain chlorinated paraffin monomer of 10 ng/mu L and the chlorine content of 55.5 percent, and adding 1ng of substitute internal standard 13 C 10 Trans-chlordane, using Milli-Q water to make the volume of the trans-chlordane to 10.00mL, and preparing short-chain chlorinated paraffin standard working solution with the concentration of 10 mu g/L and the chlorine content of 55.5 percent; the short-chain chlorinated paraffin standard working solution is treated according to the step (4)Step (5) carrying out four times of sample injection detection to obtain a total ion flow diagram chromatogram of the standard working solution; performing qualitative analysis according to the retention time, qualitative ions, quantitative ions and chromatographic peak shape comparison;
quantification: respectively taking 10 mu L of short-chain chlorinated paraffin standard solutions with the total concentration of short-chain chlorinated paraffin monomers of 10 ng/mu L and the chlorine contents of 51.5%, 53.5%, 55.5%, 59.25% and 63%, and adding 1ng of alternative internal standard 13 C 10 Trans-chlordane, using Milli-Q water to make a constant volume of 10.00mL, preparing a short-chain chlorinated paraffin standard working solution with the concentration of 10 mug/L and the chlorine content of 51.5%, 53.5%, 55.5%, 59.25% and 63%, carrying out four times of sample injection detection according to the steps (4) to (5), establishing a standard curve between the measured chlorine content and a total response factor, wherein a linear regression equation of the standard curve is y =35.2x-2053.7, wherein y is the total response factor, x is the measured chlorine content, a correlation coefficient is 0.972, and the standard curve has a good linear relation, and a detection limit of the method is 0.25ng/g, so that the requirements of the analysis method are met; the solute in the short-chain chlorinated paraffin standard solution is 24 short-chain chlorinated paraffin monomers, and the solvent is acetone; wherein 24 short-chain chlorinated paraffin monomers are respectively C 10 H 17 Cl 5 、C 10 H 16 Cl 6 、C 10 H 15 Cl 7 、C 10 H 14 Cl 8 、C 10 H 13 Cl 9 、C 10 H 12 Cl 10 、C 11 H 19 Cl 5 、C 11 H 18 Cl 6 、C 11 H 17 Cl 7 、C 11 H 16 Cl 8 、C 11 H 15 Cl 9 、C 11 H 14 Cl 10 、C 12 H 21 Cl 5 、C 12 H 20 Cl 6 、C 12 H 19 Cl 7 、C 12 H 18 Cl 8 、C 12 H 17 Cl 9 、C 12 H 16 Cl 10 、C 13 H 23 Cl 5 、C 13 H 22 Cl 6 、C 13 H 21 Cl 7 、C 13 H 20 Cl 8 、C 13 H 19 Cl 9 、C 13 H 18 Cl 10 ；
(7) Sample assay
And (4) comparing the quantitative ion peak area in the total ion current chromatogram obtained in the step (5) with the standard curve obtained in the step (6) after calculation, and finally obtaining the determination concentration of the short-chain chlorinated paraffin in the actual sample through conversion.
2. The method for detecting short-chain chlorinated paraffin in seafood as claimed in claim 1, wherein in the step (1), the freeze drying is to dry the seafood sample in a freeze drier for 12-24 h; the marine product sample is back muscle of fish, muscle of shrimp and crab or shellfish edible part.
3. A method of detecting short chain chlorinated paraffins in seafood as claimed in claim 1 or 2, wherein said seafood sample is no more than 0.5cm x 0.5 cm.
4. The method for detecting short-chain chlorinated paraffin in seafood according to claim 1, wherein in the step (2), the activated Florisil has a particle size of 60-100 meshes and is obtained by calcining Florisil in a muffle furnace at 550 ℃ for 12 hours; the particle size of the activated neutral silica gel is 40-46 mu m, and the activated neutral silica gel is obtained by calcining the neutral silica gel in a muffle furnace at 550 ℃ for 12 h; the activated anhydrous sodium sulfate was obtained by calcining anhydrous sodium sulfate in a muffle furnace at 650 ℃ for 6 h.
5. The method according to claim 1, wherein in the step (3), the acidic silica gel is prepared by thoroughly mixing 100g of activated silica gel and 43mL of concentrated sulfuric acid.
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