CN103869038B - The assay method of paraquat residual quantity in a kind of food - Google Patents
The assay method of paraquat residual quantity in a kind of food Download PDFInfo
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- CN103869038B CN103869038B CN201410096174.2A CN201410096174A CN103869038B CN 103869038 B CN103869038 B CN 103869038B CN 201410096174 A CN201410096174 A CN 201410096174A CN 103869038 B CN103869038 B CN 103869038B
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Abstract
The invention discloses the assay method of paraquat residual quantity in a kind of food, sample pre-treatments of the present invention is the paraquat extracted with methanol aqueous solution in food samples, then the agent of C18 and PSA dispersive solid-phase extraction is selected to purify extract, finally in conjunction with high performance liquid chromatography-Quadrupole-time of flight mass spectrometry, the quantitative and qualitative analysis being realized residual paraquat in food by the accurate mass number of compound ions is measured.The present invention effectively can reduce the matrix interference of paraquat residue detection in food, average recovery rate 80.6% ~ 96.8%, relative standard deviation is 3.9% ~ 7.1%, quantitatively be limited to 10 μ g/kg, its easy and simple to handle, quick, accurate, highly sensitive and reproducible advantage, supplementing and improving existing QuEChERS method, meeting China and European Union, the U.S., the technical requirement of Japan to corresponding product safety detection completely, providing strong technical support by for ensureing that our people's food security and export abroad trade develop in a healthy way.
Description
Technical field
The invention belongs to the determination techniques field of persticide residue, relate in particular to the assay method of paraquat residual quantity in a kind of food.
Background technology
In the proportion of crop planting processes such as fruit, vegetables, Cereals, farmland weed produces material impact to crop yield and quality.The use of herbicide in agricultural production, not only saves weeding manual labor heavy in a large number and weeding by machine's operation, and the prior loss being the reduction of agricultural output because crop smothering causes and quality, obtains considerable economic benefit.But along with people are to the concern of food-safety problem, the harm of herbicide residue to human health also receives much attention.
Paraquat (paraquat) chemical name 1,1 ,-dimethyl-4,4 ,-bipyridine cation, belongs to organic heterocyclic class quaternary ammonium salt herbicide.Be widely used as broad spectrum weeding agent, paraquat sales volumes in 2011 rank the 2nd in global herbicide is sold.Paraquat has stronger toxic action to people and animals, and very large to the redox activity influence of biosome after absorption, all harmful to lung, the heart, liver, kidney etc., current paraquat poisoning there is no effective methods for the treatment of.China, Codex Alimentary Commission (CAC), the U.S., European Union and Japan and other countries have all formulated residue limits standard to paraquat, the maximum residue limit 0.01 ~ 3.5mg/kg in the numerous food such as fruit, vegetables, fish, meat.Obviously along with popularization and the use of paraquat, the detection method tool setting up paraquat residual quantity in food has very important significance.
The Sample Pretreatment Technique that existing QuEChERS method is got up as new development represents sample-pretreating method that is quick, simple, inexpensive, efficient, stable and safety (Quick, Easy, Cheap, Effective, Rugged, Safe).Have the recovery high, analyze agricultural chemicals scope wide, processing speed is fast, the advantages such as solvent use amount is few, easy and simple to handle.The AOAC2007.01 standard method of EN15662 that spendable QuEChERS method has European Union to formulate and Official US's analytical chemistry Shi Xiehui is extensively recognized in the current world.Above-mentioned 2 methods all comprise extraction, purification 2 steps: wherein 1 extract sample with acetonitrile or containing the acetonitrile of 1% acetic acid, carry out salting-out extraction and realize acetonitrile by adding buffer salt potpourri and be separated with the liquid-liquid of sample place aqueous phase; 2 use dispersive solid-phase extraction agent and anhydrous magnesium sulfate to extraction solution purification, and the character of dispersive solid-phase extraction agent foundation sample substrate and testing compound, can select PSA, GCB, C18EC etc.But all must add anhydrous magnesium sulfate divided by removing moisture residual in middle acetonitrile.
Paraquat belongs to strong polarity quaternary ammonium compound, is very easily dissolved in water, is difficult to, with acetonitrile extraction, original QuEChERS method therefore cannot be adopted to carry out sample pre-treatments.Usual paraquat pre-treatment adopts Solid-Phase Extraction column purification, but method is more complicated, and the recovery is low, requires higher to operating personnel; Or without purification direct-detection, matrix interference is large, serious to instrumental pollution.Therefore seek and set up the QuEChERS method adapting to paraquat residue detection to be very important.
Summary of the invention
The object of this invention is to provide the assay method of paraquat residual quantity in a kind of food, to make up the deficiencies in the prior art.
Another object of the present invention is to provide a kind of sample-pretreating method, extensively recognizes to make up the existing world deficiency that spendable QuEChERS method cannot be used for paraquat residue detection.
Sample pre-treatments of the present invention is supplementing and improving existing QuEChERS method, due to the characteristic that paraquat is very easily water-soluble, the method of the acetonitrile extraction paraquat of salting-out extraction from aqueous phase causing existing QuEChERS method acetonitrile or contain 1% acetic acid cannot be practical, the present invention selects methanol aqueous solution to be Extraction solvent extracting directly from sample, ensure that the extraction efficiency of paraquat.In purifying step, because Extraction solvent is water mainly, add anhydrous magnesium sulfate in a conventional method to remove the method for residual moisture in extract and infeasible, therefore the present invention only uses dispersive solid-phase extraction agent to purify extract, and do not add anhydrous magnesium sulfate, and dispersive solid-phase extraction agent can only select C18 and PSA.
Therefore, paraquat of the present invention detects, its pre-treatment first extracts the paraquat in food samples with methanol aqueous solution, the agent of C18 and PSA dispersive solid-phase extraction is selected to purify extract again, finally in conjunction with high performance liquid chromatography-Quadrupole-time of flight mass spectrometry, the quantitative and qualitative analysis being realized residual paraquat in food by the accurate mass number of compound ions is measured.
Assay method of the present invention comprises the steps:
(1) extract
Take the food samples that homogenizes in tool plug plastic centrifuge tube, add methanol aqueous solution homogeneous and extract 1min, vibration, centrifugal;
(2) purify
Pipette supernatant that above-mentioned steps (1) obtains in plastic centrifuge tube, add Dispersive solid phase extraction agent, vortex oscillation, centrifugal, Aspirate supernatant crosses 0.22 μm of filter membrane, and gained sample liquid is to be determined;
(3) extraction standard working solution is prepared
By blank sample by above-mentioned steps (1), (2) process, with this blank sample matrix solution at 10 ~ 1000 μ g/L latitude of formulation paraquat series concentration standard working solution;
(4) liquid chromatography--Quadrupole-time of flight mass spectrometry (LC-Q TOF) measures
A) quantitative measurement: each concentration extraction standard working fluid in step (3) is carried out LC-Q TOF mensuration, with the chromatographic peak area of each concentration extraction standard working fluid, regretional analysis is carried out to its respective concentration, obtain standard working curve; Sample liquid step (2) obtained under the same conditions is injected LC-Q TOF and is measured, record the chromatographic peak area of paraquat in sample liquid, substitute into typical curve, obtain paraquat content in sample liquid, then the Mass Calculation of sample representated by liquid obtains paraquat residual quantity in sample per sample.
B) qualitative determination: target compound in the sample liquid that detecting step (2) obtains, if its quasi-molecular ion chromatographic peak retention time is consistent with extraction standard working solution; And when the relative standard deviation of the exact mass number of target compound is no more than 5ppm in its exact mass number extraction standard solution suitable for concentration, then judge to there is paraquat in this sample; If above-mentioned two conditions can not meet simultaneously, then judge not containing paraquat.
In above-mentioned steps (2), the volumetric concentration of methanol aqueous solution is 20%.
The agent of above-mentioned steps (2) mesostroma dispersive solid-phase extraction is made up of C18 and PSA, and in every milliliter of extract, C18 and PSA addition is respectively 50mg.
In above-mentioned steps (4), the mobile phase of liquid chromatography is A: methyl alcohol and Mobile phase B: containing 0.1% formic acid-5mmol/L ammonium formate aqueous solution, adopts A:B volume ratio 20:80 isocratic elution, flow velocity: 0.2mL/min.
In above-mentioned steps (4), the chromatographic column of liquid chromatography is hydrophilic chromatographic post (HILIC).
In above-mentioned steps (4), Mass Spectrometer Method uses electrospray ionization source (ESI) positive ion mode, capillary voltage is+4000V, atomization gas pressure is 275.8kPa, dry gas is nitrogen, dry gas temperature is 350 DEG C, dry gas flow velocity is 10.0L/min, reference ion m/z121.050873 and m/z922.009798, sweep limit 50-1100m/z.
In above-mentioned steps (4), Mass Spectrometer Method uses one-level full scan pattern, the accurate molecular masses 186.1159 of paraquat quasi-molecular ion.
The vortex oscillation time in above-mentioned steps (1) and (2) is 1min.
Centrifugal 5000r/min in above-mentioned steps (1) and (2), centrifugation time 3 ~ 5min.
In above-mentioned steps (1) ~ (4) sample contacts to the container comprising centrifuge tube all should be plastic material and make.
Beneficial effect of the present invention is:
The present invention effectively can reduce the matrix interference in food in paraquat residue detection, this pre-treating method is applied to the qualitative confirmation of paraquat in food in conjunction with HPLC-QTOF and quantitatively detects, average recovery rate 80.6% ~ 96.8%, relative standard deviation (RSD) is 3.9% ~ 7.1%, is quantitatively limited to 10 μ g/kg.The present invention has easy and simple to handle, quick, accurate, highly sensitive and reproducible advantage, is supplementing and improving existing QuEChERS method.Meeting China and European Union, the U.S., the technical requirement of Japan to corresponding product safety detection completely, providing strong technical support by for ensureing that our people's food security and export abroad trade develop in a healthy way.
Accompanying drawing explanation
Fig. 1 is that 10ng/mL extraction standard paraquat extracts chromatography of ions figure.
Fig. 2 is paraquat standard mass spectrogram.
Embodiment
Now with following embodiment, the present invention is described, but is not limit the scope of the invention.
The instrument used in the embodiment of the present invention and reagent:
T18Basic homogenizer (IKA, Germany); CR21G III type high speed freezing centrifuge (Hitachi, Japan); MS3 type vortex mixer (IKA, Germany); 1200 high performance liquid chromatography-6520 level Four bar flight time mass spectrum (Agilent, USA); PSA dispersive solid-phase extraction agent (Agilent, USA); C18 dispersive solid-phase extraction agent (Agilent, USA).
Reagent: methyl alcohol (HPLC level, Merke, Germany); Ammonium formate (HPLC level, CNW, Germany); Formic acid (HPLC level, CNW, Germany).
Paraquat standard substance: purity is 97.5%, purchased from German Dr Ehrenstorfer company.
Embodiment 1: the detection of paraquat residual quantity in apple
(1) sample pre-treatments
Take the apple sample 10.0g that homogenizes in 50mL tool plug plastic centrifuge tube, add 10mL methanol aqueous solution, the centrifugal 5min of vortex 1min, 5000r/min.After centrifugal, get 2mL supernatant extract in the centrifuge tube that 100mg C18 and 100mg PSA are housed, the centrifugal 3min of vortex 1min, 5000r/min.Get after supernatant crosses 0.22 μm of filter membrane, gained sample liquid measures for liquid chromatography-Quadrupole-time of flight mass spectrometry (LC-Q TOF).
(2) preparation of standard working solution
Take 25 ± 0.1mg standard items in 25mL plastics volumetric flask, dissolve with acetonitrile, constant volume obtains 1000.0 μ g/mL standard reserving solutions; Pipette 1.0mL standard reserving solution and be placed in 100mL plastics volumetric flask, obtain 10.0 μ g/mL standard intermediate liquids with acetonitrile constant volume;
With not containing the apple of paraquat after testing as blank sample, prepare vehicle solution by above-mentioned pre-treatment step, the dilution of standard intermediate liquid vehicle solution be mixed with 10,20,50,100,200,500,1000ng/mL series extraction standard working solution.
(3) liquid chromatography-Quadrupole-time of flight mass spectrometry (LC-Q TOF) measures
Quantitative measurement: each concentration extraction standard working fluid in step (3) is carried out LC-Q TOF mensuration, with the chromatographic peak area of each concentration extraction standard working fluid, regretional analysis is carried out to its respective concentration, obtain standard working curve; Sample liquid step (2) obtained under the same conditions is injected LC-Q TOF and is measured, record the chromatographic peak area of paraquat in sample liquid, substitute into typical curve, obtain paraquat content in sample liquid, then the Mass Calculation of sample representated by liquid obtains paraquat residual quantity in sample per sample.
Wherein chromatographic condition is: BEH HILIC chromatographic column (2.1mm × 100mm, 1.7 μm; U.S. Waters); Mobile phase: methyl alcohol and containing 0.1% formic acid-5mmol/L ammonium formate water, with volume ratio 20:80 isocratic elution; Flow velocity: 0.2mL/min; Column temperature: 30 DEG C; Sample size: 2 μ L.
Wherein mass spectrometry parameters is: electrospray ionization source (ESI) positive ion mode scans; Dry gas temperature 350 DEG C, dry gas flow velocity 10L/min, atomization gas pressure 275.8kPa, capillary voltage 4kV, capillary outlet voltage 190V, scan mode: one-level full scan, reference ion m/z121.050873 and m/z922.009798, sweep limit 50-1100m/z.
Qualitative Identification: target compound in the sample liquid that detecting step (2) obtains, if its quasi-molecular ion chromatographic peak retention time is consistent with extraction standard working solution; And when the relative standard deviation of the exact mass number of target compound is no more than 5ppm in its exact mass number extraction standard solution suitable for concentration, then judge to there is paraquat in this sample; If above-mentioned two conditions can not meet simultaneously, then judge not containing paraquat.
Standard working curve and detection limit:
With the chromatographic peak area of extraction standard working solution, regretional analysis is carried out to its respective concentration, obtain standard working curve.In the sample that 3 times of signal to noise ratio (S/N ratio)s (S/N) are corresponding, testing concentration is as detection limit (LOD), in the sample of 10 times of signal to noise ratio (S/N ratio) (S/N) correspondences, testing concentration is as quantitative limit (LOQ), obtains detection limit and the quantitative limit of each determinand.Result display (as shown in table 1), related coefficient is greater than 0.999, and quantitative limit and detection limit are respectively 10 μ g/kg and 5 μ g/kg.
The retention time of table 1 paraquat, regression equation, related coefficient, quantitative limit and detection limit
Title | Retention time (min) | Regression equation | Related coefficient | Quantitative limit (μ g/kg) | Detection limit (μ g/kg) |
Paraquat | 3.65 | Y=11019.1307X-44748.6835 | 0.9990 | 10 | 5 |
Recovery of standard addition and repeatability as follows:
With not containing the apple of paraquat after testing as blank sample, add the paraquat standard solution of above-mentioned low middle high variable concentrations level, the determination of residual amount is carried out by above-mentioned treatment step after adding 30min, mensuration concentration and agricultural chemicals theory are added concentration compare, obtain agricultural chemicals TIANZHU XINGNAO Capsul, each Pitch-based sphere replicate determination 6 times, obtain its relative standard deviation, measurement result is in table 2.
The recovery of table 2 paraquat and repeatability (n=6)
As can be seen from Table 2, in 3 mark-on levels, the recovery of paraquat is 80.6% ~ 96.8%, and relative standard deviation (RSD) is 3.9% ~ 7.1%, illustrates that the recovery of the inventive method is higher, reproducible.
Obviously, the present invention can make up paraquat residue detection in prior art cannot use the technological deficiency of QuEChERS method pre-treatment, improves the sensitivity that LC-Q TOF detects, and realizes the accurate analysis that in food, paraquat is residual.
Above embodiment is only be described the preferred embodiment of the present invention, not scope of the present invention is limited, under not departing from the present invention and designing the prerequisite of spirit, the various modification that the common engineering in this area is made technical scheme of the present invention and improvement, all should fall into claim of the present invention.
Claims (5)
1. the assay method of paraquat residual quantity in food, is characterized in that comprising the steps:
(1) extract
Take the food samples that homogenizes in tool plug plastic centrifuge tube, add methanol aqueous solution vortex oscillation, centrifugal;
(2) purify
Pipette supernatant that above-mentioned steps (1) obtains in plastic centrifuge tube, add Dispersive solid phase extraction agent, vortex oscillation, centrifugal, Aspirate supernatant crosses 0.22 μm of filter membrane, and gained sample liquid is to be determined;
(3) extraction standard working solution is prepared
By blank sample by above-mentioned steps (1), (2) process, with this blank sample matrix solution at 10 ~ 1000 μ g/L latitude of formulation paraquat series concentration standard working solution;
(4) liquid chromatography--Quadrupole-time of flight mass spectrometry (LC-Q TOF) measures
A) quantitative measurement: each concentration extraction standard working fluid in step (3) is carried out LC-Q TOF mensuration, with the chromatographic peak area of each concentration extraction standard working fluid, regretional analysis is carried out to its respective concentration, obtain standard working curve; Sample liquid step (2) obtained under the same conditions is injected LC-Q TOF and is measured, record the chromatographic peak area of paraquat in sample liquid, substitute into typical curve, obtain paraquat content in sample liquid, then the Mass Calculation of sample representated by liquid obtains paraquat residual quantity in sample per sample;
B) qualitative determination: target compound in the sample liquid that detecting step (2) obtains, if its quasi-molecular ion chromatographic peak retention time is consistent with extraction standard working solution; And when the relative standard deviation of the exact mass number of target compound is no more than limit value in its exact mass number extraction standard solution suitable for concentration, then judge to there is paraquat in this sample; If above-mentioned two conditions can not meet simultaneously, then judge not containing paraquat;
The agent of above-mentioned steps (2) mesostroma dispersive solid-phase extraction is made up of C18 and PSA, and in every milliliter of extract, C18 and PSA addition is respectively 50mg;
In above-mentioned steps (1), the volumetric concentration of methanol aqueous solution is 20%;
In above-mentioned steps (4), the mobile phase of liquid chromatography is A: methyl alcohol and Mobile phase B: containing 0.1% formic acid-5mmol/L ammonium formate aqueous solution, adopts A:B volume ratio 20:80 isocratic elution, flow velocity: 0.2mL/min;
In above-mentioned steps (4), the chromatographic column of liquid chromatography is hydrophilic chromatographic post;
In above-mentioned steps (4), Mass Spectrometer Method uses electrospray ionization source (ESI) positive ion mode, capillary voltage is+4000V, atomization gas pressure is 275.8kPa, dry gas is nitrogen, dry gas temperature is 350 DEG C, dry gas flow velocity is 10.0L/min, reference ion m/z121.050873 and m/z922.009798, sweep limit 50-1100m/z.
2. the assay method of paraquat residual quantity in food as claimed in claim 1, it is characterized in that in above-mentioned steps (4), Mass Spectrometer Method uses one-level full scan pattern, the accurate molecular masses of paraquat quasi-molecular ion is 186.1159.
3. the assay method of paraquat residual quantity in food as claimed in claim 1, is characterized in that the vortex oscillation time in above-mentioned steps (1) and (2) is 1min.
4. the assay method of paraquat residual quantity in food as claimed in claim 1, is characterized in that the centrifugal 5000r/min in above-mentioned steps (1) and (2), centrifugation time 3-5min.
5. the assay method of paraquat residual quantity in food as claimed in claim 1, it is characterized in that sample contacts in above-mentioned steps (1) ~ (4) to the container comprising centrifuge tube all should be plastic material and make.
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CN107607489B (en) * | 2017-08-01 | 2020-11-17 | 东莞市第六人民医院(东莞市慢性病防治院、东莞市职业病防治中心,东莞市皮肤性病防治所,东莞市结核病防治所,东莞市医学美容中心) | Paraquat rapid detection method and detection device thereof |
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CN112730372B (en) * | 2020-11-26 | 2023-04-11 | 中国科学院合肥物质科学研究院 | Flexible surface enhanced Raman substrate, preparation method thereof and paraquat detection method |
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