CN113433227A - Method for detecting 6-chloropicolinic acid in vegetables and fruits - Google Patents
Method for detecting 6-chloropicolinic acid in vegetables and fruits Download PDFInfo
- Publication number
- CN113433227A CN113433227A CN202110023179.2A CN202110023179A CN113433227A CN 113433227 A CN113433227 A CN 113433227A CN 202110023179 A CN202110023179 A CN 202110023179A CN 113433227 A CN113433227 A CN 113433227A
- Authority
- CN
- China
- Prior art keywords
- detecting
- vegetables
- chloropicolinic acid
- supernatant
- acetonitrile
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N30/14—Preparation by elimination of some components
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/62—Detectors specially adapted therefor
- G01N30/72—Mass spectrometers
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N2030/042—Standards
- G01N2030/047—Standards external
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N30/14—Preparation by elimination of some components
- G01N2030/146—Preparation by elimination of some components using membranes
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Other Investigation Or Analysis Of Materials By Electrical Means (AREA)
Abstract
The invention belongs to the technical field of food detection, and discloses a method for detecting 6-chloropicolinic acid in vegetables and fruits, which comprises the steps of preparing vegetable and fruit samples, extracting acetonitrile-formic acid solution and centrifuging; purifying the supernatant obtained by centrifugation; detecting the purified supernatant by using a liquid chromatography-mass spectrometer; and comparing the retention time of the detected target pesticide chromatographic peak with the retention time of the corresponding standard chromatographic peak, and carrying out qualitative and quantitative analysis. The invention provides a method for detecting and analyzing 6-chloropicolinic acid in vegetables and fruits by using LC-MS/MS (liquid chromatography-mass spectrometry), which is suitable for the liquid chromatography-mass spectrometry combined determination of the residual amount of 6-chloropicolinic acid in vegetables and fruits. The invention adopts a T3 chromatographic column for separation, detects in a positive ion mode, selects a mobile phase of acetonitrile +10mmol/L ammonium acetate solution, adopts isocratic elution for the mobile phase, and can eliminate the residual effect of the column to obtain good reproducibility.
Description
Technical Field
The invention belongs to the technical field of food detection, and particularly relates to a method for detecting 6-chloropicolinic acid in vegetables and fruits.
Background
At present, trichloropicoline can be used as a nitrogen oxidation inhibitor and a soil nitrogen fertilizer synergist due to the selective activity of azotobacter, and is generally called as imidacloprid. When the compound is applied together with urea and nitrogen fertilizer, the oxidation of ammonium ions in soil can be delayed, and the compound is also an important pesticide and medical intermediate. It rapidly degrades to 6-chloropicolinic acid in plants, animals and soil and is also the only significant chemical residue resulting from the application of azapirine.
The detection method of trichloromethyl pyridine metabolite 6-chloropicolinic acid in plant-derived food in China is relatively complex, tedious, time-consuming and labor-consuming. The detection of 6-chloropicolinic acid in vegetables and fruits is mainly carried out by adopting a gas chromatography-mass spectrometry method, the pretreatment time is long, and the steps are complicated. Since the instrument is not suitable for detecting the acid extract, the time for deacidification and dehydration is consumed. Key points in the pre-derivatization treatment need to be well controlled to improve the recovery rate and ensure the detection result.
Through the above analysis, the problems and defects of the prior art are as follows: the existing detection method of 6-chloropicolinic acid is complex, tedious, time-consuming and labor-consuming, and has low recovery rate and inaccurate detection result.
The difficulty in solving the above problems and defects is: when optimizing the conditions of liquid quality, the effect of the positive and negative ion reaction, the influence of different chromatographic columns and mobile phase gradients need to be examined.
The significance of solving the problems and the defects is as follows: a rapid detection method for the residual quantity of 6-chloropicolinic acid is established, the quality of agricultural products is ensured, the level of enterprise management and detection mechanisms is integrally improved, and the method has a particularly important significance in promoting the processing of food and agricultural products.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a method for detecting 6-chloropicolinic acid in vegetables and fruits.
The invention is realized in such a way that the method for detecting 6-chloropicolinic acid in vegetables and fruits comprises the following steps:
extracting vegetable and fruit samples by using acidic acetonitrile, carrying out dispersive solid-phase extraction and purification on an extracting solution, detecting by using a liquid chromatography-mass spectrometer, and carrying out quantitative analysis by using an external standard method.
Further, the method for detecting 6-chloropicolinic acid in the vegetables and fruits comprises the following steps:
step one, preparing a vegetable and fruit sample, accurately weighing 10g of a sample in a 50mL plastic centrifuge tube, adding 10mL of acetonitrile-formic acid solution, violently shaking for 1min, adding 3g of NaCl, continuing shaking for 15min, and centrifuging;
purifying the supernatant obtained by centrifugation; detecting the purified supernatant by using a liquid chromatography-mass spectrometer; and comparing the retention time of the detected target pesticide chromatographic peak with the retention time of the corresponding standard chromatographic peak, and carrying out qualitative and quantitative analysis.
Further, in the first step, the preparation method of the vegetable and fruit sample comprises the following steps: selecting vegetable or fruit samples, chopping the selected samples, mixing well, sampling by quartering method or directly placing into a tissue triturator, mashing into homogenate, and placing into a polyethylene bottle.
Further, in the first step, the selecting the vegetable or fruit sample comprises:
for smaller samples of smaller individuals, all the samples are processed after sampling;
for a large and basically uniform sample of an individual, the sample is divided or cut into small blocks on a symmetry axis or a symmetry plane for post-treatment;
for samples which are slender, flat or have different component contents in each part, small pieces are cut at different positions or are cut into small pieces for post-treatment.
Further, in step one, the centrifugation comprises: centrifuging at 4200r/min for 5 min.
Further, in the second step, the purifying the supernatant obtained by centrifugation comprises: sucking 4mL of supernatant, adding the supernatant into a 15mL plastic centrifuge tube containing 300mg of anhydrous magnesium sulfate, 100mg of PSA, 100mg of C18 and 50mg of GCB, and uniformly mixing for 1min in a vortex manner; centrifuging, accurately sucking 2.5mL of supernatant into a 10mL test tube, and blowing nitrogen in a water bath until the supernatant is nearly dry; 10mL of acetonitrile was added for redissolution and the solution was filtered through a microporous membrane.
Further, the centrifuging comprises: centrifuging at 10000r/min for 5 min.
Further, the water bath temperature is as follows: at 40 ℃.
Further, in the second step, the detecting the purified supernatant by using a liquid chromatography-mass spectrometer comprises:
chromatographic parameters:
an Atlantis T3 chromatographic column is adopted; mobile phase: flow rate: 0.35 mL/min; mobile phase: a: methanol; b: acetonitrile and 10mmol/L ammonium acetate solution; 20% A + 80% B isocratic elution;
mass spectrum conditions:
ESI positive ion scan mode: multiple reaction monitoring parameters: 35.0psi of gas curtain gas, 3000V of normalizing voltage, 500 ℃ of ion source, 50psi of electrospray gas, 60psi of auxiliary heating gas, 8psi of collision gas and 25mSec of residence time.
Further, the mass spectrometry conditions further comprise: the quantitative parent ion is 158.1, and the daughter ion is 112; the parent ion is identified as 160.1 and the daughter ion is identified as 114;
the de-clustering voltage is 12V, the collision energy is 27, the entrance voltage is 10eV, and MRM positive ions are collected within 0-5 min.
By combining all the technical schemes, the invention has the advantages and positive effects that: the invention provides a method for detecting and analyzing 6-chloropicolinic acid in vegetables and fruits by using LC-MS/MS (liquid chromatography-mass spectrometry), which is suitable for the liquid chromatography-mass spectrometry combined determination of the residual amount of 6-chloropicolinic acid in vegetables and fruits. The test method is simple, accurate and effective to operate and high in sensitivity.
The invention establishes an effective test method of 6-chloropicolinic acid by optimizing the prior art and innovating the instrument conditions. The invention detects the vegetables and fruits such as cucumber, tomato, cabbage heart, pepper, ginger, scallion, banana, peach, orange, grape, cherry, pear and the like, and has good reproducibility. The method is simple to operate, does not need to be derived to consume a large amount of time, increases the detection efficiency, and has higher sensitivity because the detection lower limit is lower than the specified detection lower limit of 0.1mg/kg and the detection lower limit of 0.05mg/kg in other documents. The invention can provide a simpler, accurate, stable and effective detection method and improve the detection efficiency.
According to the invention, acetonitrile is selected, 0.1mL of formic acid is added, 6-chloropicolinic acid can be well extracted into an acetonitrile layer, and the recovery rate of 6-chloropicolinic acid is high; the invention purifies the extracting solution, can effectively remove impurities in the sample and improve the recovery rate of 6-chloropicolinic acid; according to the invention, a T3 column is selected for separation, the chromatographic column is a reversed-phase C18 chromatographic column based on an ultra-pure silica gel matrix, the peak shape of 6-chloropicolinic acid is sharp, no tailing exists, the sensitivity is high, the object to be detected can be well separated, and the peak-off time is about 3.75 min.
The invention adopts a T3 chromatographic column for separation, detects in a positive ion mode, selects a mobile phase of acetonitrile +10mmol/L ammonium acetate solution, adopts isocratic elution for the mobile phase, and can eliminate the residual effect of the column to obtain good reproducibility. The present invention determines the quantitative and qualitative ion pairs to be 158.1/112 and 160.1/114. The selection of the ion pairs has high sensitivity and less peak-to-peak mutual interference.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present application, and it is obvious for those skilled in the art that other drawings can be obtained from the drawings without creative efforts.
Fig. 1 is a flowchart of a method for detecting 6-chloropicolinic acid in vegetables and fruits according to an embodiment of the present invention.
FIG. 2 is a chromatogram-mass spectrum of an Atlantis T3 chromatographic column for 6-chloropicolinic acid separation provided by the embodiment of the invention; FIG. 2 (a) spectrum 158.1/112; (b)160.1/114 mass spectrum.
FIG. 3 is a schematic diagram of the working curve of 6-chloropicolinic acid provided by the example of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Aiming at the problems in the prior art, the invention provides a method for detecting 6-chloropicolinic acid in vegetables and fruits, and the invention is described in detail with reference to the attached drawings.
The method for detecting 6-chloropicolinic acid in vegetables and fruits provided by the embodiment of the invention comprises the following steps: extracting vegetable and fruit samples by using acidic acetonitrile, carrying out dispersive solid-phase extraction and purification on an extracting solution, detecting by using a liquid chromatography-mass spectrometer, and carrying out quantitative analysis by using an external standard method.
As shown in fig. 1, the method for detecting 6-chloropicolinic acid in vegetables and fruits provided by the embodiment of the invention comprises the following steps:
s101, preparing a vegetable and fruit sample, accurately weighing 10g of sample in a 50mL plastic centrifuge tube, adding 10mL of acetonitrile-formic acid solution, violently shaking for 1min, adding 3g of NaCl, continuing shaking for 15min, and centrifuging at 4200r/min for 5 min;
s102, sucking 4mL of supernatant, adding the supernatant into a 15mL plastic centrifuge tube containing 300mg of anhydrous magnesium sulfate, 100mg of PSA, 100mg of C18 and 50mg of GCB, and uniformly mixing for 1min in a vortex manner;
s103, centrifuging at 10000r/min for 5min, accurately sucking 2.5mL of supernatant into a 10mL test tube, and blowing nitrogen to be nearly dry in a water bath at 40 ℃; adding 10mL of acetonitrile for redissolution, and filtering the mixture through a microporous filter membrane;
s104, detecting by using a liquid chromatography-mass spectrometer; and comparing the retention time of the detected target pesticide chromatographic peak with the retention time of the corresponding standard chromatographic peak, and carrying out qualitative and quantitative analysis.
In step S101, the method for preparing a vegetable and fruit sample provided by the embodiment of the present invention includes: selecting vegetable or fruit samples, chopping the selected samples, mixing well, sampling by quartering method or directly placing into a tissue triturator, mashing into homogenate, and placing into a polyethylene bottle.
In step S101, selecting a vegetable or fruit sample provided in the embodiment of the present invention includes:
for smaller samples of smaller individuals, all the samples are processed after sampling;
for a large and basically uniform sample of an individual, the sample is divided or cut into small blocks on a symmetry axis or a symmetry plane for post-treatment;
for samples which are slender, flat or have different component contents in each part, small pieces are cut at different positions or are cut into small pieces for post-treatment.
In step S104, the detecting the purified supernatant with the liquid chromatography-mass spectrometer provided by the embodiment of the present invention includes:
chromatographic parameters:
an Atlantis T3 chromatographic column is adopted; mobile phase: flow rate: 0.35 mL/min; mobile phase: a: methanol; b: acetonitrile and 10mmol/L ammonium acetate solution; 20% A + 80% B isocratic elution;
mass spectrum conditions:
ESI positive ion scan mode: multiple reaction monitoring parameters: 35.0psi of gas curtain gas, positive ionization voltage of +3000V, 500 ℃ of ion source temperature, 50psi of electrospray gas, 60psi of auxiliary heating gas, 8psi of collision gas and 25mSec of residence time;
the quantitative parent ion is 158.1, and the daughter ion is 112; the parent ion is identified as 160.1 and the daughter ion is identified as 114;
the de-clustering voltage is 12V, the collision energy is 27, the entrance voltage is 10eV, and MRM positive ions are collected within 0-5 min.
The technical solution of the present invention is further described below with reference to specific examples.
Example 1:
1 range
The method is suitable for the liquid chromatography-mass spectrometry combined determination method of the 6-chloropicolinic acid residue in vegetables and fruits.
2 normative citation document
The regulations on residual pesticides in food, hong Kong, China, is issued by the environmental sanitation agency of food, hong Kong, China, according to the regulations on public health and municipal administration (Chapter 132), No. 55 (1).
Principle 3
Extracting a sample by using acidic acetonitrile, purifying an extracting solution by dispersion solid-phase extraction, detecting by using a liquid chromatography-mass spectrometer, and quantifying by using an external standard method.
4 reagents and materials
Unless otherwise stated, only analytically pure reagents were used in the analysis, primary water as specified in level GB/T6682.
4.1 reagents
4.1.1 acetonitrile (CH3CN, CAS number: 75-05-8): pure chromatography
4.1.2 methanol
4.1.3 sodium chloride (NaCl, CAS number: 7647-14-5).
4.1.4 formic acid (CH2O2, CAS number: 64-18-6)
4.1.5 magnesium sulfate (MgSO4, CAS number 7487-88-9)
4.2 preparation of solution
Acetonitrile-formic acid solution (99+ 1): 10mL of formic acid is weighed and added into 990mL of acetonitrile, and the mixture is uniformly mixed.
4.3 Standard substance
6-chloropicolinic acid standard, CAS No.: 4684-94-0 percent and the purity is 99.0 percent
4.4 Standard solution preparation
4.4.1 Standard stock solution (1000 mg/L): accurately weighing 10mg (accurate to 0.1mg) of 6-chloropicolinic acid standard substance, dissolving with methanol, diluting to 10mL, storing at-18 ℃ in a dark place, and keeping the effective period for 1 year.
4.4.2 Standard working solutions: a certain amount of the standard stock solution is sucked into a 250mL volumetric flask and is fixed to the scale with acetonitrile. The standard working solution is stored at 0-4 ℃ in the dark, and the validity period is 1 month.
4.4.3 matrix standard working solutions: the blank matrix solution is dried by nitrogen, added with 1mL of mixed standard solution with corresponding mass concentration for redissolution, and filtered by a microporous filter membrane (4.5.6). The matrix mix standard working solution should be ready for use.
Note: the blank matrix solution samples should correspond to the sample treatment samples.
4.5 materials
4.5.1 Ethylenediamine-N-propylsilanized silica gel (PSA): 40 to 60 μm.
4.5.2 octadecylsilane bonded silica (C18): 40 to 60 μm.
4.5.3 Graphitized Carbon Black (GCB): 40 to 120 μm.
4.5.4 Millipore filter (organic phase): 13 mm. times.0.22. mu.m.
5 instruments
5.1UFLC LC-20ADXR high performance liquid chromatograph (Shimadzu, Japan); API QTRAP 5500 quadrupole/linear ion trap mass spectrometer, with ESI ion source (Sciex, USA).
5.2 analytical balance: sensory amounts 0.1mg and 0.01 g.
5.3 high-speed refiner: the rotating speed is not lower than 15000 r/min.
5.4 centrifuge: the rotating speed is not lower than 4200 r/min.
5.5 centrifuge: the rotating speed is not lower than 12000 r/min.
5.6 nitrogen blowing instrument: the temperature can be controlled.
5.7 reciprocating oscillator: heidolph, Germany
5.8200 μ L, 1000 μ L, 5mL Proline, Saedodes Baide pipettor:
5.9 Sadoris Germany model MX-GX1061 electric Mixer model Panasonic: xiamen Jian Song electric appliance Co Ltd
Model 5.10Joyou (Jiuyang) JYS-M01 flour mill, Jiuyang GmbH
6 sample preparation
6.1 sample preparation
The sampling of vegetables and fruits was performed according to the GB/T8855 regulations. The sampling site was performed as specified in appendix A of GB 2763 and 2019. For smaller individual samples, all treatment was done after sampling; for larger basically uniform samples of individuals, the samples can be divided or cut into small blocks on a symmetry axis or a symmetry plane for post-treatment; for samples which are slender, flat or have different component contents in each part, small pieces can be cut at different positions or cut into small pieces for post-treatment; cutting the obtained sample, mixing, sampling by quartering method or directly mashing in tissue mashing machine to obtain homogenate, and placing into polyethylene bottle.
6.2 sample storage
The samples were stored separately as tested and ready for use. Storing at-16-20 deg.C.
7 analytical procedure
7.1 pretreatment
Accurately weighing 10g of sample (accurate to 0.01g) into a 50mL plastic centrifuge tube, adding 10mL of acetonitrile-formic acid solution, violently shaking for 1min, adding 3g of NaCl, continuing shaking for 15min, centrifuging at 4200r/min for 5min, and purifying.
7.2 purification
Aspirate 4mL of supernatant into a 15mL plastic centrifuge tube containing 300mg of anhydrous magnesium sulfate, 100mg of PSA, 100mg of C18, and 50mg of GCB, and vortex and mix for 1 min. Centrifuging at 10000r/min for 5min, accurately sucking 2.5mL of supernatant into a 10mL test tube, and blowing nitrogen to be nearly dry in a water bath at 40 ℃.10 mL of acetonitrile was added for reconstitution and the solution was filtered through a microporous membrane for assay.
7.4 determination
7.4.1 Instrument reference conditions
A chromatographic column: atlantis T3 column (100 mm. times.4.6 mm, 3 μm, Volter. U.S.A.)
Mobile phase: the flow rate is 0.35 mL/min; the mobile phase A is methanol; b, acetonitrile +10mmol/L ammonium acetate solution; 20% A + 80% B isocratic.
7.4.2 Mass Spectrometry conditions
ESI positive ion scan mode: multiple Reaction Monitoring (MRM) parameters: air Curtain Gas (Curtain Gas)35.0psi, normalizing voltage (IonSprayVoltage) +3000V, Ion Source Temperature (Temperature)500 ℃, electrospray Gas (Ion Source Gas1)50psi, auxiliary heating Gas (Ion Source Gas2)60psi, collisional Gas (Collision Gas)8psi, residence Time (Dwell Time)25 mSec. The optimized parent ion Q1, child ion Q3, Declustering Potential (Declustering Potential), Collision Energy (Collision Energy), and exit Potential (Collision Cell exitpoint) are shown in Table 1. Collecting MRM positive ions at an inlet voltage (entry Potential) of 10eV for 0-5 min.
TABLE 16 Retention time, parent ions, daughter ions, declustering Voltage and Collision energy of chloropicolinic acid
7.4.3 Standard operating Curve
Accurately sucking a certain amount of mixed standard solution, gradually releasing the mixed standard solution into standard working solutions with mass concentrations of 2.5 mu g/L, 5.0 mu g/L, 10 mu g/L, 20 mu g/L and 25 mu g/L by using acetonitrile, and determining by using a liquid chromatography-mass spectrometer. And drawing a standard curve by taking the peak area of the pesticide quantitative ion pair as a vertical coordinate and the mass concentration of the pesticide standard solution as a horizontal coordinate.
7.4.3 qualitative and quantitative
7.4.3.1 retention time
The retention time of the target pesticide chromatographic peak in the tested sample is compared with that of the corresponding standard chromatographic peak, and the relative error is within +/-2.5%.
8 demonstration of main experimental techniques
8.1 optimization of purification conditions
8.1.1 acetonitrile is selected, and 0.1mL of formic acid is added, so that the 6-chloropicolinic acid can be well extracted into an acetonitrile layer in an acidic acetonitrile system. Experiments prove that the recovery rate of the 6-chloropicolinic acid is very low when the raw materials are extracted by acetonitrile or ethyl acetate.
8.1.2 purification of the extract
After the sample is extracted by acetonitrile, some polar and medium-polar impurities are also extracted into the acetonitrile, such as vitamins, pigments and the like, and PSA, C18 and graphite carbon black powder are selected as adsorbents according to the properties of the impurities. In the experiment, a plurality of purification modes are compared at the same time, firstly, a traditional solid phase extraction method is used for passing through an activated carbon small column, and sample liquid is collected; secondly, using Sin-QuEChERs produced by Beijing Green Cotton science and technology Limited to purify the small column in one step, and collecting the purifying liquid at one time; and thirdly, the purification mode of anhydrous magnesium sulfate and PSA by using the traditional QuEChERS method. The recovery rates of all three schemes are lower than those of the scheme used in the invention.
8.2 selection of liquid chromatography conditions
8.2.1 selection of chromatography columns
The 6-chloropicolinic acid has stronger polarity, is sensitive to light, heat and oxygen, is easy to oxidize, and almost has no reservation on the traditional reversed phase chromatographic column. In the experiment, a T3 column and a common C18 column are selected to carry out the determination on the 6-chloropicolinic acid standard solution under the optimized chromatographic conditions respectively applicable. Through experiments, a T3 chromatographic column is finally selected for separation, the chromatographic column is a reversed-phase C18 chromatographic column based on an ultrapure silica gel matrix, the 6-chloropicolinic acid has a sharp peak shape, no tailing and high sensitivity, the object to be detected can be well separated, and the peak-off time is about 3.75min (figure 2), so the T3 chromatographic column is selected for experiments.
8.2.2 selection of Mobile phase
The invention adopts a T3 chromatographic column for separation and detection in a positive ion mode, and selects an organic phase as an acetonitrile solution and a water phase as an ammonium acetate water solution. Because the use of salt in the liquid chromatography-mass spectrometry combination can generally improve the peak shape and sensitivity of the object to be detected, the lower the concentration of the ammonium acetate aqueous solution is, the higher the response value of the object to be detected is, and the more symmetrical and non-trailing peak shape is finally found. Thus, the mobile phase was chosen to be acetonitrile +10mmol/L ammonium acetate solution. In addition, in the experimental process, it is found that when the Atlantis T3 chromatographic column is used for gradient elution, if the next needle does not reach the sufficient balance of the mobile phase, the column residual effect of the column is very strong, and good reproducibility is difficult to obtain, and the needle needs to be washed for many times in a blank solution sample injection mode to eliminate the last needle residue, so that in order to eliminate the column residual effect and obtain good reproducibility, the mobile phase is eluted at equal degrees. Therefore, to eliminate the residual effect of the column for good reproducibility, the mobile phase was eluted isocratically.
8.3 optimization of Mass Spectrometry conditions
In a positive ion mode, performing primary mass spectrometry (Q1 scanning) on 6-chloropicolinic acid to obtain a parent ion peak, and performing secondary mass spectrometry (child ion scanning) on the parent ion peak to obtain 4 pairs of fragment ion information, wherein the noise of 158.1/140 and 160.1/142 is high, and finally, the quantitative and qualitative ion pairs are determined to be 158.1/112 and 160.1/114. The selection of the ion pairs has high sensitivity and less peak-to-peak mutual interference. See fig. 2.
9 methodological validation
9.1 Standard Curve and Linear Range
The average recovery rate under the working curve of the standard solution is respectively inspected by adopting a negative Chinese cabbage standard-adding 0.01mg/kg sample (repeating the measurement for 6 times). The experimental result shows that the average recovery rate of 6-chloropicolinic acid calculated by 6 samples according to a standard curve is 108 percent. 2.5, 5.0, 10.0, 20.0, 25.0 and 50.0 mu g/L of standard working solution are prepared respectively, and the standard curve is shown in figure 3. The results show that the linearity of 6-chloropicolinic acid is good (r)2Not less than 0.999). The limit of the present invention is 0.01 mg/kg.
9.2 lower limit of measurement
The limit of the quantitative determination of the 6-chloropicolinic acid is 0.01 mg/kg.
9.3 recovery and precision of the Process
The precision of the Chinese cabbage sample is measured, the recovery rate of the apple sample is tested, and the precision and the recovery rate data are shown in tables 2 and 3.
Table 26-chloropicolinic acid precision experimental results (n ═ 6)
TABLE 36 experimental results on recovery of chloropicolinic acid
The basic information of 6-chloropicolinic acid is shown in Table 4.
TABLE 4 basic information of standards
The above description is only for the purpose of illustrating the present invention and the appended claims are not to be construed as limiting the scope of the invention, which is intended to cover all modifications, equivalents and improvements that are within the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A method for detecting 6-chloropicolinic acid in vegetables and fruits is characterized by comprising the following steps: extracting vegetable and fruit samples by using acidic acetonitrile, carrying out dispersive solid-phase extraction and purification on an extracting solution, detecting by using a liquid chromatography-mass spectrometer, and carrying out quantitative analysis by using an external standard method.
2. The method of claim 1, wherein the method for detecting 6-chloropicolinic acid in a vegetable comprises the steps of:
step one, preparing a vegetable and fruit sample, accurately weighing 10g of a sample in a 50mL plastic centrifuge tube, adding 10mL of acetonitrile-formic acid solution, violently shaking for 1min, adding 3g of NaCl, continuing shaking for 15min, and centrifuging;
purifying the supernatant obtained by centrifugation; detecting the purified supernatant by using a liquid chromatography-mass spectrometer; and comparing the retention time of the detected target pesticide chromatographic peak with the retention time of the corresponding standard chromatographic peak, and carrying out qualitative and quantitative analysis.
3. The method of claim 2, wherein in step one, the method for preparing a sample of vegetable or fruit comprises: selecting vegetable or fruit samples, chopping the selected samples, mixing well, sampling by quartering method or directly placing into a tissue triturator, mashing into homogenate, and placing into a polyethylene bottle.
4. The method according to claim 2, wherein the step one, selecting the vegetable or fruit sample comprises:
for smaller samples of smaller individuals, all the samples are processed after sampling;
for a large and basically uniform sample of an individual, the sample is divided or cut into small blocks on a symmetry axis or a symmetry plane for post-treatment;
for samples which are slender, flat or have different component contents in each part, small pieces are cut at different positions or are cut into small pieces for post-treatment.
5. The method of claim 2, wherein the centrifugation step comprises: centrifuging at 4200r/min for 5 min.
6. The method for detecting 6-chloropicolinic acid in vegetables and fruits according to claim 2, wherein in the second step, the purifying the supernatant obtained by centrifugation comprises: sucking 4mL of supernatant, adding the supernatant into a 15mL plastic centrifuge tube containing 300mg of anhydrous magnesium sulfate, 100mg of PSA, 100mg of C18 and 50mg of GCB, and uniformly mixing for 1min in a vortex manner; centrifuging, accurately sucking 2.5mL of supernatant into a 10mL test tube, and blowing nitrogen in a water bath until the supernatant is nearly dry; 10mL of acetonitrile was added for redissolution and the solution was filtered through a microporous membrane.
7. The method of claim 6, wherein the centrifuging comprises: centrifuging at 10000r/min for 5 min.
8. The method for detecting 6-chloropicolinic acid in vegetables and fruits according to claim 6, wherein the water bath temperature is: at 40 ℃.
9. The method for detecting 6-chloropicolinic acid in vegetables and fruits according to claim 2, wherein in the second step, the detecting the purified supernatant by using a liquid chromatography-mass spectrometer comprises:
chromatographic parameters:
an Atlantis T3 chromatographic column is adopted; mobile phase: flow rate: 0.35 mL/min; mobile phase: a: methanol; b: acetonitrile and 10mmol/L ammonium acetate solution; 20% A + 80% B isocratic elution;
mass spectrum conditions:
ESI positive ion scan mode: multiple reaction monitoring parameters: 35.0psi of gas curtain gas, 3000V of normalizing voltage, 500 ℃ of ion source, 50psi of electrospray gas, 60psi of auxiliary heating gas, 8psi of collision gas and 25mSec of residence time.
10. The method of claim 9, wherein the mass spectrometric conditions further comprise: the quantitative parent ion is 158.1, and the daughter ion is 112; the parent ion is identified as 160.1 and the daughter ion is identified as 114;
the de-clustering voltage is 12V, the collision energy is 27, the entrance voltage is 10eV, and MRM positive ions are collected within 0-5 min.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110023179.2A CN113433227A (en) | 2021-01-08 | 2021-01-08 | Method for detecting 6-chloropicolinic acid in vegetables and fruits |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110023179.2A CN113433227A (en) | 2021-01-08 | 2021-01-08 | Method for detecting 6-chloropicolinic acid in vegetables and fruits |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN113433227A true CN113433227A (en) | 2021-09-24 |
Family
ID=77752780
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110023179.2A Pending CN113433227A (en) | 2021-01-08 | 2021-01-08 | Method for detecting 6-chloropicolinic acid in vegetables and fruits |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113433227A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114062552A (en) * | 2021-11-16 | 2022-02-18 | 上海市农业科学院 | Method for detecting imidacloprid metabolite in plant-derived food |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109507335A (en) * | 2018-12-29 | 2019-03-22 | 上海交通大学医学院附属新华医院 | Utilize the method for a variety of different type environmental contaminants in LC-MS-MS high throughput detection urine |
| CN110196294A (en) * | 2019-05-30 | 2019-09-03 | 暨南大学 | The Solid Phase Extraction detection method of anabasine insecticide and its converted product in a kind of water |
| CN110455937A (en) * | 2019-06-13 | 2019-11-15 | 中国水产科学研究院长江水产研究所 | Imidacloprid is metabolized object detecting method in a kind of aquatic products |
| CN110514766A (en) * | 2019-09-11 | 2019-11-29 | 中国检验检疫科学研究院 | The measuring method of trichloromethyl pyridine in a kind of food |
-
2021
- 2021-01-08 CN CN202110023179.2A patent/CN113433227A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109507335A (en) * | 2018-12-29 | 2019-03-22 | 上海交通大学医学院附属新华医院 | Utilize the method for a variety of different type environmental contaminants in LC-MS-MS high throughput detection urine |
| CN110196294A (en) * | 2019-05-30 | 2019-09-03 | 暨南大学 | The Solid Phase Extraction detection method of anabasine insecticide and its converted product in a kind of water |
| CN110455937A (en) * | 2019-06-13 | 2019-11-15 | 中国水产科学研究院长江水产研究所 | Imidacloprid is metabolized object detecting method in a kind of aquatic products |
| CN110514766A (en) * | 2019-09-11 | 2019-11-29 | 中国检验检疫科学研究院 | The measuring method of trichloromethyl pyridine in a kind of food |
Non-Patent Citations (7)
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114062552A (en) * | 2021-11-16 | 2022-02-18 | 上海市农业科学院 | Method for detecting imidacloprid metabolite in plant-derived food |
| CN114062552B (en) * | 2021-11-16 | 2023-05-30 | 上海市农业科学院 | Method for detecting imidacloprid metabolites in plant-derived food |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN102735784A (en) | Method for simultaneously determining one hundred pesticide residuals in traditional Chinese medicine through ultrahigh performance liquid chromatography-tandem quadrupole mass spectrum | |
| CN110514766B (en) | Method for determining trichloromethylpyridine in food | |
| CN105738494A (en) | Isotope dilution high resolution chromaticness combination method for simultaneously detecting organic chlorine pesticides and polychlorinated biphenyl in biological sample, and application | |
| CN113295797A (en) | Method for rapidly detecting ethyl carbamate in white spirit based on ultra-high performance liquid chromatography combined high-resolution mass spectrometry | |
| CN103308641A (en) | High performance liquid chromatography-tandem mass spectrometry measuring method of three amide herbicides in tobacco and tobacco products | |
| Ash et al. | Analysis of clinical specimens using inductively coupled plasma mass spectrometry | |
| CN109828071B (en) | Method for simultaneously detecting 9 water-infused drug residues in pork | |
| CN113433227A (en) | Method for detecting 6-chloropicolinic acid in vegetables and fruits | |
| CN111426776B (en) | Application of HQR as characteristic marker of schefflera octophylla honey | |
| Jiang et al. | Rapid determination of dimethoate in nanoliter of juice using surface desorption atmospheric pressure chemical ionization mass spectrometry | |
| CN107860858A (en) | A kind of method for high-flux analysis of mycotoxin in plant medicine material | |
| CN112505190A (en) | Method for detecting acrylic acid in soil | |
| Khetagoudar et al. | Multiresidue Pesticide Analysis in Cabbage and Cauliflower Using Gas Chromatography Tandem Mass Spectrometry (GC‐MS/MS) | |
| CN104165947B (en) | A kind of method of auxin and ABA content in quantitative assay plant | |
| CN114354790B (en) | Method for detecting 7 halogenated carbazole compounds in aquatic product | |
| CN103995046A (en) | Application and method for detecting forchlorfenuron residues in crops by using ionic migration spectrometer | |
| CN113109471B (en) | LCMSMS (liquid crystal display module medium) method for rapidly and simultaneously detecting chlorothalonil and metabolites thereof in vegetables and fruits | |
| CN105651870B (en) | The remaining method of pesticide in a kind of gas chromatography-mass spectrum detection liquid beverage | |
| CN111595976B (en) | Method for analyzing residues of six alternaria alternata toxins in solanaceous vegetables | |
| CN111337611A (en) | Method for detecting malachite green, leucomalachite green, crystal violet and leucocyte crystal violet in aquatic products | |
| Jin-Xiang et al. | Solid phase microextraction-ion mobility spectrometry for rapid determination of trace dichlorovos in tea drinks | |
| CN109324139A (en) | Ribosylzeatin liquid-liquid extraction-liquid chromatography-tandem mass spectrometry measuring method in a kind of tobacco leaf | |
| CN111879879B (en) | Method for detecting methamidophos and octachlorodipropyl ether in plant food | |
| CN109580808A (en) | A kind of method that QuEChERS-LC-MS/MS measures 10 kinds of aromatic amines in cigarette smoke simultaneously | |
| CN111896654B (en) | Method for analyzing acetochlor in ginger and metabolites EMA and HEMA thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |