The assay method of fipronil bisamide residual quantity in a kind of vegetables and fruit
Technical field
The present invention relates to the assay method of fipronil bisamide residual quantity in a kind of vegetables and fruit, be more particularly the method adopting Gas Chromatography-Negative chemical ionization source-mass spectrum (GC-NCI-MS) qualitative, quantitative to measure fipronil bisamide content residual in vegetables and fruit, belong to the determination techniques field of persticide residue.
Background technology
Fipronil bisamide (Flubendiamide), trade name ridge is sung, it is the Novel ortho benzenedicarboxamide insecticides that Japanese agricultural chemicals company (claiming Co., Ltd.) researches and develops, to nearly all Lepidoptera class pest, all there is good activity, not only have excellent activity to adult and larva, and speed of action is fast, the lasting period is long.Definitely first-class to rice-stem borer and leaf roll snout moth's larva effect.Very low to honeybee toxicity, also very low to carp (hydrobiological representative) toxicity.To there being beneficial insect there is no activity (almost non-toxic) under general consumption, producing without cross resistance with existing pesticide, being suitable for very much the control that existing pesticide produces the insect of resistance.Chemical name is: the iodo-N ' of 3--(2-mesyl-1,1-dimethyl ethane base-N-{4-[the fluoro-1-of 1,2,2,2-tetra-(trifluoromethyl) ethyl]-0-tolyl } phthalamide.CAS accession number is 272451-65-7, and molecular weight is 682.39, and structural formula is:
Fipronil bisamide went on the market in 2007 at first in Japan's (being registered in various vegetables and fruit tree), within 2008, be used for paddy rice and cotton in India's registration, equal for vegetables, fruit tree and paddy rice in Korea S, a lot of country obtains registration, is used for vegetables and paddy rice etc. in China successively registration.This pesticide acts on the ryanodine receptor in insect bodies, and ryanodine receptor is the passage controlling calcium ion release in insect bodies inner cell.This pesticide can stimulate ryanodine receptor, irreversibly opens calcium channel, and a large amount of calcium ion is constantly released, and stimulate insect muscle contracts last, insect is stopped action and takes food, vomiting, hungry, dehydration, de-excrement, final stiff contracting and dead.Fipronil bisamide high-efficiency broad spectrum, all has good control effects to lepidopterous Noctuidae, Pyralidae, Carposinidae, tortricid, miller section, diamond-back moth section, Gelechidae, Gracilariidae etc., can also control coleoptera Culculionidae, Chrysomelidae; Diptera Agromyzidae; The multiple non-lepidoptera pest such as Bemisia tabaci.
Along with the registration of fipronil bisamide, popularization and use, as U.S. in China's veterinary antibiotics main exit market, European Union and Japan and other countries, residue limits standard is formulated to it.On March 19th, 2007, the U.S. make an announcement intend in following food/the residual regulation of table fipronil bisamide (flubendiamide) limits the quantity: Pericarppium Armeniacae Amarum: 9.0ppm; Rape greenery class subgroup: 6.0ppm; Rape head and tubers subgroup: 0.60ppm; Field corn grain: 0.02ppm; Land for growing field crops puffed rice teosinte bar: 15.0ppm; Shell band cob corn: 0.02ppm; Corn forage: 9.0ppm; Corn grass bar: 25.0ppm; Cottonseed: 2.0ppm; Ginning accessory substance: 60.0ppm; The operatic circle group: 0.7ppm; Drupe group: 1.6ppm; Grape: 1.4ppm; Nut group: 0.06ppm; Gumbo: 0.30ppm; Cucurbit plant group: 0.20ppm; Fruit type vegetable group: 0.30ppm; Leafy vegetable, does not comprise rape class: 11.0ppm; Table in plant product, alfalfa wheel forage: 0.15ppm; Alfalfa hay: 0.04ppm; Barley hay: 0.04ppm; Barley straw: 0.07ppm; Buckwheat: 0.07ppm; Clover forage: 0.15ppm; Alfalfa hay: 0.04; Green grass material: 0.15ppm; Hay: 0.04ppm; Store careless feed: 0.27ppm; Pearl millet forage: 0.15ppm; Pearl millet hay: 0.04ppm; Broomcorn millet forage: 0.15ppm; Broomcorn millet hay: 0.04ppm; Broomcorn millet bar: 0.07ppm; Oat forage: 0.15ppm; Oat hay: 0.04ppm; Oat bar: 0.07ppm; Rye forage: 0.15ppm; Rye bar: 0.07ppm; Jowar forage: 0.03ppm; Jowar millet straw bar: 0.06ppm; Soybean forage: 0.02ppm; Soybean hay: 0.04ppm; Mexico's broomcorn millet forage: 0.15ppm; Mexico's broomcorn millet hay: 0.04ppm; Mexico's broomcorn millet bar: 0.07ppm; Triticale forage: 0.15ppm; Triticale hay: 0.04ppm; Triticale bar: 0.07ppm; Wheat forage: 0.15ppm; Wheat hay: 0.03ppm; Wheat straw: 0.03ppm; Table in animal commodity, beef liver: 0.60ppm; Ox kidney: 0.60ppm; Thin cattle meat: 0.10ppm; Ox fat meat: 0.80ppm; Egg: 0.03ppm; Goat liver: 0.60ppm; Goat kidney: 0.60ppm; Goat lean meat: 0.10ppm; Goat fat meat: 0.80ppm; Horse liver: 0.60ppm; Horse kidney: 0.60ppm; Horse lean meat: 0.10ppm; Horse fat meat: 0.80ppm; Pork liver: 0.60ppm; Pig kidney: 0.60ppm; Lean pork: 0.10ppm; Pig fat meat: 0.80ppm; Milk: 0.20ppm.
On March 4th, 2010, the residue limits of European Union's revision pesticide fipronil bisamide in cucurbitaceae vegetable, eggplant and beans.In the cucurbitaceae vegetable that pericarp can not eat, eggplant and beans, the MRL of fipronil bisamide is 0.2mg/kg, in the cucurbitaceae vegetable that pericarp is edible and eggplant, fipronil bisamide MRL is 0.1mg/kg, in the beans that pericarp is edible, the MRL of fipronil bisamide is 0.5mg/kg, in strawberry, the MRL of fipronil bisamide is 0.2mg/kg, European Union and Japan, to the food agricultural product not formulating maximum permission residue limits, all carry out " uniform limit " of 0.01mg/L.
In recent years, a lot of to the research of fipronil bisamide residues detection method in varieties of food items agricultural product, the detection method of report all adopts liquid chromatography (LC) or Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) to measure the detection method of cyanogen insect amide residual quantity in vegetables and fruit, using LC-MS/MS to measure food Residual Pesticides in Farm Produce has fast, easy, sensitivity advantages of higher, but due to its price costly, a lot of testing agency, enterprise or scientific research institutions do not configure this instrument or configuration number of units is less, during due to different compounds employing LC-MS/MS detection, different mobile phases or chromatographic column need be used, such needs constantly change chromatographic column, mobile phase also expends the long time and balances system, this constrains the application of LC-MS/MS to a certain extent.The gaschromatographic mass spectrometry (GC-NCI-MS) in outfit negative chemical ionization source is analyzed food Residual Pesticides in Farm Produce tool and is had great advantage, Negative chemical ionization (NCI source) is called as mass spectrum " soft ionization source ", to the analysis thing containing electronegativity group, there is high selectivity and high sensitivity, because its characteristic is strong, when utilizing it to carry out retention analysis, matrix interference is little, can carry out qualitative and quantitative analysis very accurately to object.Existing various testing agency and enterprise have all purchased gas chromatograph-mass spectrometer (GCMS) (GC-MS), generally also be provided with Negative chemical ionization (NCI), now a lot of class agricultural chemicals is all containing electronegativity group, and organochlorine and pyrethroid pesticide molecule are mostly containing strong electronegative group such as-F ,-Cl ,-Br or-COO-, organophosphorus pesticide molecule is mostly containing the=electronegativity group such as S ,-OR ,-P ,-O-,-Cl or-P=O, and mostly containing-F group in the novel agrochemical developed in recent years, therefore, use GC-NCI-MS conveniently can realize the multi-residue analysis of Multiple Pesticides, compared with GC-NCI-MS, better antijamming capability can be obtained, lower sensitivity and better selectivity, fipronil bisamide belongs to electronegativity compound, but have no the report of the GC-NCI-MS detection method of fipronil bisamide residual quantity in vegetables and fruit up to now, therefore, the detection method setting up fipronil bisamide residual quantity in Gas Chromatography-Negative chemical ionization source-mass spectrum (GC-NCI-MS) qualitative and quantitative analysis vegetables and fruit is significant.
Summary of the invention
The object of this invention is to provide the assay method of fipronil bisamide residual quantity in a kind of vegetables and fruit.
For realizing above object, the technical solution adopted in the present invention is: the assay method of fipronil bisamide residual quantity in a kind of vegetables and fruit, comprises the steps:
(1) extract
Take sample in tool plug centrifuge tube, add acetonitrile or extract 1min containing the acetonitrile solution homogeneous of 1% acetic acid, add the one in sodium chloride or sodium acetate and anhydrous magnesium sulfate, centrifugal after vibration.
(2) purify
Pipette sample extracting solution supernatant in centrifuge tube, add Dispersive solid phase extraction agent, vortex oscillation, centrifugal, draw after a certain amount of scavenging solution nitrogen dries up, dissolve constant volume with acetone/normal hexane mixed solvent that volume ratio is 1/1, after crossing film, treat that Gas Chromatography-Negative chemical ionization source-mass spectrum (GC-NCI-MS) detects.
(3) preparation of standard working solution
When same kind matrix blank sample not containing fipronil bisamide is processed by above-mentioned steps (1), (2), obtain sample extraction purification residue, add appropriate solvent and mixed standard solution, vortex mixes, and is mixed with the fipronil bisamide series hybrid standard working fluid of at least 3 concentration.
(4) Gas Chromatography-Negative chemical ionization source-mass spectroscopy (GC-NCI-MS) measures
The standard working solution of each concentration gradient in step (3) is carried out GC-NCI-MS mensuration, with the chromatographic peak area of standard working solution, regretional analysis is carried out to its respective concentration, obtain standard working curve; Under the same conditions the sample liquid after purification in step (2) is injected GC-NCI-MS to measure, record the chromatographic peak area of fipronil bisamide in sample liquid, substitute into typical curve, obtain fipronil bisamide content in sample liquid, then the Mass Calculation of sample representated by liquid obtains fipronil bisamide residual quantity in sample per sample.If cyanogen insect amide residual quantity exceedes the range of linearity upper limit in upper machine solution, with constant volume solvent, upper machine solution concentration need be diluted within the range of linearity.
Step (1) if in sample dehydrated vegetables and fruit, need sample weighting amount be reduced, and add suitable quantity of water and fully infiltrate.
Add sodium chloride when adopting acetonitrile to extract in step (1) to saltout, add sodium acetate when adopting the acetonitrile solution containing 1% acetic acid to extract and saltout; A certain amount of water need be added when the sample of moisture content less is saltoutd.
The agent of step (2) mesostroma dispersive solid-phase extraction is by anhydrous magnesium sulfate, C
18with PSA composition, anhydrous magnesium sulfate, C in every volume extract
18150mg, 50mg and 25mg is respectively with PSA addition.
In step (4), GC conditions is: chromatographic column: HP-5MS capillary chromatographic column, column length 30m, internal diameter 0.25mm, thickness 0.25 μm; Injector temperature 250 DEG C; Carrier gas: He, not shunt mode sample introduction, sample size: 1 μ L; Constant current mode, flow velocity 1.0mL/min; Heating schedule: initial temperature 60 DEG C keeps 2min, rises to 200 DEG C, then rises to 220 DEG C with the speed of 2 DEG C per minute, then rise to 280 DEG C with the speed of 20 DEG C per minute with the speed of 20 DEG C per minute, keeps 10min; Transmission line temperature: 280 DEG C.
In step (4), Mass Spectrometry Conditions is: ion source temperature 150 DEG C; Quadrupole rod temperature 150 DEG C; Ionization pattern: negative chemical ionization, i.e. NCI pattern, energy 70eV; Scan mode: Salbutamol Selected Ion Monitoring (SIM) pattern, the ion of monitoring is: 407,408,409.
When measuring sample liquid and extraction standard working solution in step (4), if sample liquid Pesticides chromatographic peak retention time agricultural chemicals retention time corresponding to standard solution is consistent, and in the sample mass spectrogram after background correction, selected ion all occurs, and abundance of ions than with the abundance of ions of standard solution than consistent, then can judge to exist in sample liquid this agricultural chemicals; If above-mentioned two conditions can not meet simultaneously, then judge not containing this kind of agricultural chemicals.
Beneficial effect of the present invention is:
The present invention utilizes dispersive solid-phase extraction technology, establish sample-pretreating method that is easy, that also can effectively avoid sample mesostroma to disturb fast, this pre-treating method is applied to the qualitative confirmation of fipronil bisamide and quantitatively detection in vegetables and fruit in conjunction with GC-NCI-MS, average recovery rate is 93.2% ~ 103.1%, average relative standard's deviation (RSD) is 4.6% ~ 7.4%, detection limit, lower than 1.15 μ g/kg, has easy and simple to handle, quick, accurate, highly sensitive and reproducible advantage.The technical requirement of the countries such as the U.S., Japan, European Union to corresponding product safety detection being met, 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
The GC-NCI-MS Selective ion mode chromatogram of Fig. 1 to be concentration be fipronil bisamide mark liquid of 100ng/mL.
Fig. 2 is not containing the GC-NCI-MS Selective ion mode chromatogram of the grape blank sample of fipronil bisamide.
Fig. 3 is the GC-NCI-MS Selective ion mode chromatogram of the fipronil bisamide be added in blank grape matrix.
The fipronil bisamide standard working curve that Fig. 4 is is substrate preparation with the grape blank sample not containing fipronil bisamide.
Embodiment
Now with following embodiment, the present invention is described, but is not limit the scope of the invention.
The instrument used in embodiment and reagent
T18Basic homogenizer (IKA, Germany); 5810R hydro-extractor (Eppendorf, Germany); MS3 basic model vortex mixer (IKA, Germany); 7890N gas chromatography-5975C mass spectrometer (Agilent, USA); Primary secondary amine (PSA) adsorbent (40 ~ 60 μm), octadecylsilane Bonded Phase (C
18) cleanser (40 ~ 60 μm) is all purchased from Anjelen Sci. & Tech. Inc of the U.S..
Reagent: acetonitrile, acetone, normal hexane (HPLC level, Merke, Germany); Acetic acid (HPLC level, CNW, Germany); Anhydrous magnesium sulfate, sodium chloride and sodium acetate are pure for analyzing, all purchased from Chemical Reagent Co., Ltd., Sinopharm Group.
Standard substance: purity >=98.0%, purchased from German Dr.Ehrenstorfer company.
Embodiment 1: the detection of fipronil bisamide residual quantity in grape
(1) sample pre-treatments
Taking grape 10.0g through fully mixing in 50mL centrifuge tube, accurately adding 20mL acetonitrile, homogeneous extracts 1min, adds 3g anhydrous magnesium sulfate and 2g sodium chloride, after vortex 1min, and the centrifugal 5min of 7000r/min.After centrifugal, get 6mL acetonitrile extract and be transferred to 900mg anhydrous magnesium sulfate, 300mg C are housed
18with in the centrifuge tube of 150mg PSA, the centrifugal 5min of vortex 1min, 5000r/min.Get 4mL supernatant in nitrogen blowpipe, dry up in 40 DEG C of nitrogen, add acetone/normal hexane mixed solvent dissolved residue that volume ratio is 1/1, after vortex mixed film, move in sample injection bottle and treat that GC-NCI-MS measures.
(2) preparation of standard working solution
Accurately take 25 ± 0.1mg standard items in 25mL 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 volumetric flask, obtain 10.0 μ g/mL standard intermediate liquids with the acetone/normal hexane mixed solvent constant volume by volume ratio being 1/1; 10 μ g/mL standard solution dilutions are made into 5,2,1,0.5,0.2,0.1 μ g/mL standard solution.Strawberry blank sample not containing spiral shell worm ethyl ester is pressed above-mentioned pre-treatment step process, obtain sample extraction purification residue, acetone/normal hexane mixed solvent and the above-mentioned mixed standard solution of 100 μ L that 900 μ L volume ratios are 1/1 is added in this residue, vortex mixes, and is made into 10,20,50,100,200,500 μ g/L extraction standard working solutions.
(3) Gas Chromatography-Negative chemical ionization source-mass spectroscopy (GC-NCI-MS) measures
The standard working solution of variable concentrations gradient is injected GC-NCI-MS respectively, carries out the quantitative test of fipronil bisamide content with external standard method, namely with the chromatographic peak area of standard working solution, regretional analysis is carried out to its respective concentration, obtain typical curve; Under the same conditions sample extracting solution is injected GC-NCI-MS to measure, record the chromatographic peak area of fipronil bisamide in sample liquid, substitute into typical curve, obtain fipronil bisamide content in sample liquid, then the Mass Calculation of sample representated by liquid obtains fipronil bisamide residual quantity in sample per sample.If cyanogen insect amide residual quantity exceedes the range of linearity upper limit in upper machine solution, with constant volume solvent, upper machine solution concentration need be diluted within the range of linearity.
Wherein chromatographic condition is:
Chromatographic column: HP-5MS capillary chromatographic column, column length 30m, internal diameter 0.25mm, thickness 0.25 μm.
Injector temperature: 250.0 DEG C, sample introduction pattern: Splitless injecting samples, sample size: 1 μ L.
Carrier gas: He, constant current mode, flow velocity 1.0mL/min.
Stove case heating schedule: initial temperature 60 DEG C keeps 2min, rises to 200 DEG C, then rises to 220 DEG C with the speed of 2 DEG C per minute, then rise to 280 DEG C with the speed of 20 DEG C per minute with the speed of 20 DEG C per minute, keeps 10min;
Transmission line temperature: 280 DEG C.
Wherein, mass spectrometry parameters is:
Ionization pattern: negative chemical ionization, i.e. NCI pattern, energy 70eV.
Ion source temperature: 150 DEG C.
Quadrupole rod temperature 150 DEG C.
Scan mode: Salbutamol Selected Ion Monitoring (SIM) pattern.
The ion of SIM monitoring is: 407,408,409, and quota ion is 407.
Qualitative Identification: at identical conditions, if sample liquid Pesticides chromatographic peak retention time agricultural chemicals retention time corresponding to standard solution is consistent, and in the sample mass spectrogram after background correction, selected ion all occurs, and abundance of ions than with the abundance of ions of standard solution than consistent, then can judge to exist in sample liquid this agricultural chemicals; If above-mentioned two conditions can not meet simultaneously, then judge not containing this kind of agricultural chemicals.
With the chromatographic peak area of standard working solution, regretional analysis is carried out to its respective concentration, obtain standard working curve as table 1.
The typical curve of fipronil bisamide in table 1 grape bare substrate
Title |
Retention time (min) |
Regression equation |
Related coefficient |
Fipronil bisamide Flubendiamide |
27.07 |
Y=6.8218X+27.64 |
0.9998 |
Recovery of standard addition and repeatability:
The fipronil bisamide standard solution of 10, a 20 and 2000 μ g/kg3 concentration level is added in the grape not containing fipronil bisamide, add after 30min until agricultural chemicals and carry out the determination of residual amount by above-mentioned treatment step, purification constant volume liquid is diluted to residual quantity within the range of linearity with acetone/normal hexane mixed solvent that volume ratio is 1/1 before adding the sample liquid GC-MS mensuration to be measured of concentration by 2000 μ g/kg.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.As can be seen from Table 2, in 3 mark-on levels, the average recovery rate of fipronil bisamide is 93.2% ~ 96.2%, and average relative standard's deviation (RSD) is 4.8% ~ 7.2%, illustrates that the recovery of the inventive method is higher, reproducible.
The recovery of table 2 fipronil bisamide and repeatability (n=6)
Detection limit:
The fipronil bisamide extraction standard working solution of variable concentrations is injected GC-NCI-MS, calculate detection limit with the cycles of concentration (cycles of concentration of grape is 2.0 times) of 3 times of signal to noise ratio (S/N ratio)s of least concentration extraction standard solution chromatographic peak and sample handling processes, detecting of fipronil bisamide is limited to 1.15 μ g/kg.
Embodiment 2: the detection of fipronil bisamide residual quantity in Chinese cabbage
(1) sample pre-treatments
Take Chinese cabbage 10.0g through fully mixing in 50mL centrifuge tube, accurately add the acetonitrile solution of 20mL containing 1% acetic acid, homogeneous extracts 1min, adds 3g anhydrous magnesium sulfate and 2g sodium acetate, after vortex 1min, and the centrifugal 5min of 7000r/min.After centrifugal, get 6mL acetonitrile extract and be transferred to 900mg anhydrous magnesium sulfate, 300mg C are housed
18with in the centrifuge tube of 150mg PSA, the centrifugal 5min of vortex 1min, 5000r/min.Get 4mL supernatant in nitrogen blowpipe, dry up in 40 DEG C of nitrogen, add acetone/normal hexane mixed solvent dissolved residue that volume ratio is 1/1, after vortex after mixing, move in sample injection bottle and treat that GC-NCI-MS measures.
(2) preparation of standard working solution
10 μ g/mL standard solution dilutions are made into 5,2,1,0.5,0.2,0.1 μ g/mL standard solution.Chinese cabbage blank sample not containing fipronil bisamide is pressed above-mentioned pre-treatment step process, obtain sample extraction purification residue, acetone/normal hexane mixed solvent and the above-mentioned mixed standard solution of 100 μ L that 900 μ L volume ratios are 1/1 is added in this residue, vortex mixes, and is made into 10,20,50,100,200,500 μ g/L extraction standard working solutions.
(3) Gas Chromatography-Negative chemical ionization source-mass spectroscopy (GC-NCI-MS) measures
Operation steps, chromatogram are consistent with the mensuration of fipronil bisamide in above-mentioned grape sample with Mass Spectrometry Conditions.
Qualitative Identification:
Consistent with the mensuration of fipronil bisamide in above-mentioned grape sample.
Linear relationship:
Carry out regretional analysis with the chromatographic peak area of standard working solution to its respective concentration, obtaining standard working curve is Y=23.078X-260.49, and related coefficient is 0.9989.
Recovery of standard addition and repeatability:
Add 0.01 in not containing the Chinese cabbage of fipronil bisamide, 0.02,0.2, the fipronil bisamide standard solution of 10mg/kg 4 concentration levels, add after 30min until agricultural chemicals and carry out the determination of residual amount by above-mentioned treatment step, purification constant volume liquid is diluted to residual quantity within the range of linearity with acetone/normal hexane mixed solvent that volume ratio is 1/1 before adding the sample liquid GC-MS mensuration to be measured of concentration by 10mg/kg.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 3.As can be seen from Table 3, in 4 mark-on levels, the average recovery rate of fipronil bisamide is 93.8% ~ 103.1%, and average relative standard's deviation (RSD) is 4.6% ~ 7.4%, illustrates that the recovery of the inventive method is high, reproducible.
The recovery of table 3 fipronil bisamide and repeatability (n=6)
Detection limit:
The fipronil bisamide extraction standard working solution of variable concentrations is injected GC-NCI-MS, calculate detection limit with the cycles of concentration (cycles of concentration of Chinese cabbage is 2.0 times) of 3 times of signal to noise ratio (S/N ratio)s of least concentration extraction standard solution chromatographic peak and sample handling processes, detecting of fipronil bisamide is limited to 0.61 μ g/kg.
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 in protection domain that claims of the present invention determine.