CN114935611A

CN114935611A - Method for rapidly determining fenpropathrin enantiomer residue in fruit and vegetable paste by ultra-high performance phase-combination chromatography

Info

Publication number: CN114935611A
Application number: CN202210479825.0A
Authority: CN
Inventors: 张文华; 侯建波; 谢文; 张雅琴; 祝泽龙; 汪鹏; 胡晓莉; 赵非; 毛壬熠; 徐敦明
Original assignee: Zhejiang Academy Of Science & Technology For Inspection & Quarantine
Current assignee: Zhejiang Academy Of Science & Technology For Inspection & Quarantine
Priority date: 2022-05-05
Filing date: 2022-05-05
Publication date: 2022-08-23
Anticipated expiration: 2042-05-05
Also published as: CN114935611B

Abstract

The invention relates to a method for detecting pesticide residues in fruit and vegetable puree, in particular to a method for rapidly determining fenpropathrin enantiomer residues in fruit and vegetable puree (apple puree, strawberry puree and tomato puree) by using an ultra-high performance phase-coincidence chromatography. According to the method, a sample is extracted by acetonitrile, purified by a solid phase extraction column, separated by an CHIRALPAK AD-3 chiral chromatographic column, subjected to gradient elution by taking supercritical carbon dioxide-methanol as a mobile phase at a flow rate of 1.5mL/min, and subjected to detection wavelength of 230nm, and quantified by an external standard method. The quantitative limit of the two fenpropathrin enantiomers is 0.2mg/kg, the linear range is 1.0-20mg/L, the linear correlation coefficient is greater than 0.9992, the recovery rate ranges from 80.6% to 105% under 3 standard addition levels (0.2, 0.4 and 2.0 mg/kg), and the relative standard deviation ranges from 2.6% to 7.7%. The method is convenient to operate, good in separation effect, green and environment-friendly, and can meet the requirement of detecting fenpropathrin enantiomer residues in the main complementary fruit and vegetable puree for infants.

Description

Method for rapidly determining fenpropathrin enantiomer residue in fruit and vegetable paste by ultra-high performance phase-combination chromatography

Technical Field

The invention relates to a method for detecting pesticide residues in fruit and vegetable puree, in particular to a method for rapidly determining fenpropathrin enantiomer residues in fruit and vegetable puree by using an ultra-high performance phase-matching chromatography.

Background

Fenpropathrin (Fenpropathrin), the chemical name of which is alpha-cyano-3-phenoxybenzyl-2, 2,3, 3-tetramethylcyclopropane ester, is an important pyrethroid insecticide and acaricide, has moderate toxicity and wide insecticidal spectrum, is widely used for disease control of fruits and vegetables such as oranges, apples and litchis, and the problem of food and environmental pollution caused by the large amount of Fenpropathrin is also widely regarded by people. The study shows that fenpropathrin has 1 chiral carbon atom, and has a pair of enantiomers, and the structures of the fenpropathrin and (+) -fenpropathrin ^[1-3] As shown in fig. 1.

The difference of the insecticidal activity and the degradation speed of different enantiomers of fenpropathrin is larger, wherein the insecticidal activity of (+) -fenpropathrin is higher than that of (-) -fenpropathrin, and the degradation speed is faster ^[1] . In the agricultural production process, ifThe single high-activity (+) -fenpropathrin is beneficial to reducing the using amount of the fenpropathrin and reducing the pollution of pesticide to the ecological environment, and the fenpropathrin is still produced and used in a raceme form at present. In order to control the standard use of fenpropathrin, countries set the maximum residue limit standard of the pesticide in fruits and vegetables, and table 1 lists the residue limit of fenpropathrin in fruits and vegetables added in common infant complementary food fruit and vegetable puree. However, these regulations only stipulate the safety limits for the use of the racemate of fenpropathrin, and do not precisely stipulate the residual limits of (+) -fenpropathrin and (-) -fenpropathrin.

TABLE 1 residue limit requirements of fenpropathrin pesticide on apple, strawberry and tomato

At present, Capillary Electrophoresis Chromatography (CEC) ^[4,5] Gas Chromatography (GC) ^[6,7] Gas chromatography-mass spectrometry (GC-MS) ^[8,9] High Performance Liquid Chromatography (HPLC) ^[10-12] Liquid chromatography-tandem mass spectrometry (LC-MS/MS) ^[13-15] The methods play an important role in the field of chiral compound separation. CEC chromatogram peaks were good, but analysis time was long; the GC and GC-MS have high sensitivity and good separation effect, but mainly analyze compounds with lower boiling points and good thermal stability; the HPLC separation degree is good, but the consumption of organic reagents is large; LC-MS/MS has high accuracy, but the instrument is expensive and has high cost. Ultra-high performance integrated phase chromatography (UPC) ² ) Has received wide attention as a novel high-efficiency chromatographic separation technology, the main mobile phase of which is supercritical state CO ₂ The density and polarity of the mobile phase can be changed by adjusting the system back pressure, the chromatographic column temperature and the proportion of the organic solvent, thereby achieving the purpose of precisely controlling the separation effect of the target object ^[16] Has obvious advantages in application of chiral separation ^[17-20] . Currently, UPC ² The application of the technology to the separation of fenpropathrin enantiomer and the residue determination is not reported.

Disclosure of Invention

In order to solve the technical problems, the invention aims to provide a method for rapidly determining fenpropathrin enantiomer residues in fruit and vegetable paste by using an ultra-high performance combined phase chromatography, which optimizes main parameters such as a pretreatment method of the fenpropathrin enantiomer in the fruit and vegetable paste, instrument chromatographic separation conditions and the like, and analyzes and determines main commercially available infant complementary food fruit and vegetable paste samples. The method is efficient, rapid, convenient and environment-friendly, is convenient to operate, realizes the accurate analysis of the drug effect of the drug enantiomer, and provides technical support for the development of other chiral drugs, the accurate determination of residues and the drug quality evaluation.

In order to achieve the purpose, the invention adopts the following technical scheme:

a method for rapidly determining fenpropathrin enantiomer residues in fruit and vegetable paste by ultra-high performance phase-combining chromatography, wherein the structures of two fenpropathrin enantiomers are (-) -fenpropathrin and (+) -fenpropathrin, and the method comprises the following steps:

1) sample extraction

Weighing 5g of sample, accurately weighing the sample to 0.01g, adding 20mL of acetonitrile into a 50mL centrifuge tube, homogenizing and extracting, adding 3.0 g of sodium chloride, uniformly mixing by vortex, centrifuging at 4000 r/min for 5min, and transferring supernatant into a concentration bottle; adding 20mL of acetonitrile into the lower-layer residue, repeatedly extracting for 1 time, combining 2 times of supernate, concentrating to near dryness by using a rotary evaporator, dissolving by using 10mL of acetonitrile and water at a ratio of 1: 1(v/v), and waiting for purification;

2) purification

Placing the liquid to be purified in an activated HLB column, loading the liquid, then leaching with 5mL of water, discarding the leaching solution, draining, eluting with 10mL of acetone, collecting the eluent, drying the eluent in water bath at 40 ℃ by nitrogen drying till the eluent is nearly dry, adding 1mL of n-heptane/isopropanol (9: 1 (v/v)) to dissolve and fix the volume, filtering the volume-fixed liquid through a 0.22 mu m filter membrane, and waiting for detection;

3) determination of chromatographic conditions

And (3) chromatographic column: CHIRALPAK AD-3, 150mm × 3.0mm, 3 μm; mobile phase: a is CO ₂ B is methanol; gradient elution procedure:

0-0.2 min, 3% volume ratio B, 97% volume ratio A;

0.2-0.21 min, 3-10% of volume ratio B, and 97-90% of volume ratio A;

0.21-2 min, 10% volume ratio B, 90% volume ratio A;

2-2.5 min, 10-30% of volume ratio B and 90-70% of volume ratio A;

2.5-3 min, 3% volume ratio B, 97% volume ratio A;

and (3) system backpressure: 17.2 MPa; the detection wavelength is 230 nm; the flow rate is 1.5 mL/min; the column temperature is 31 ℃; the sample size was 5. mu.L.

Preferably, the racemate standard stock solution is prepared as follows: accurately weighing 0.01g of fenpropathrin racemate standard substance to be accurate to 0.1mg, accurately metering the volume to a 10mL volumetric flask by using isopropanol, and preparing 1.0g/L of racemate standard stock solution.

Preferably, the standard intermediate solution of fenpropathrin racemate: a defined amount of the racemate standard stock solution was accurately aspirated and diluted with n-heptane/isopropanol (9: 1, v/v) to 20.0mg/L of standard intermediate solution.

Preferably, the enantiomeric standard stock solutions are prepared as follows: respectively and accurately weighing 0.01g of (-) -fenpropathrin and 0.1mg of (+) -fenpropathrin standard substance, dissolving the (-) -fenpropathrin and the (+) -fenpropathrin standard substance by using isopropanol, and fixing the volume of the solution to a 10mL volumetric flask to prepare 1.0g/L enantiomer standard stock solution.

Preferably, a mixed standard working solution of two pyrethrin enantiomers: accurately transferring certain amounts of (-) -cypermethrin and (+) -fenpropathrin enantiomer standard stock solutions respectively, and gradually diluting to series of standard working solutions of 1.0, 2.0, 4.0, 10.0 and 20.0mg/L by using n-heptane/isopropanol (v/v) of 9: 1.

Preferably, the method has the quantitative limit of 0.2mg/kg for both fenpropathrin enantiomers, the linear range of 1.0-20mg/L, the linear correlation coefficient of greater than 0.9992, the recovery rate ranges from 80.6% to 105% at 0.2, 0.4 and 2.0mg/kg 3 normalized levels, and the relative standard deviation of 2.6% to 7.7%.

By adopting the technical scheme, the invention establishes the ultra-high efficiency combined phase chromatography for separating and measuring the residue of the two fenpropathrin enantiomers in the auxiliary fruit and vegetable puree (apple puree, strawberry puree and tomato puree) for the main infantsThe method of (1). Extracting with acetonitrile, purifying with HLB column, separating with CHIRALPAK AD-3 chiral chromatographic column, and supercritical CO extracting ₂ Methanol as mobile phase, gradient elution and external standard method for quantification. The limit of quantification is 0.2mg/kg, the range of recovery rate by adding standard is 80.6-105%, and RSD is 2.6-7.7%. The method is adopted to measure the fenpropathrin enantiomer residues in 30 fruit and vegetable paste samples purchased from the market, and the detected amount is 0.21mg/kg-0.24 mg/kg.

Drawings

FIG. 1 shows the structural formulas of different enantiomers of fenpropathrin.

FIG. 2 is a spectrum of fenpropathrin enantiomer standard solution.

FIG. 3 is a graph showing the effect of different columns on the separation of the enantiomers of (-) fenpropathrin and (+) -fenpropathrin.

FIG. 4 is a graph showing the effect of different system back pressures on the separation of the enantiomers of (-) fenpropathrin and (+) -fenpropathrin.

FIG. 5 is a graph showing the effect of different solvents on the separation of (-) -fenpropathrin from (+) -fenpropathrin.

FIG. 6 is a scheme showing the resolution of the racemate of fenpropathrin.

Fig. 7 chromatogram of positive tomato puree samples.

Detailed Description

1.1 instruments, materials and reagents

Ultra-high performance phase-compatible chromatographs (Vortex, USA, equipped with PDA detectors); bench centrifuge (Thermo corporation, usa); n-1210BV rotary evaporator (Tokyo, Japan, physico-chemical Co., Ltd.); JJ500 electronic balance (doujie balance, usa); AE260 electronic balance (Mettler, switzerland); WH-861 vortex mixer (Taicano Hualida laboratory instruments Co., Ltd.); synergy185 ultrapure water instrument (Millipore, usa); nitrogen blowing apparatus (tokyo physical & chemical corporation, japan); microfiltration membrane (0.22 μm, organic phase); chromatographic columns CHIRALPAK AD-3, OJ-H, IC (Daiiluol chiral technology (Shanghai) Co., Ltd.); column Acquity Trefoil CEL1 (Waters corporation, usa).

Isopropanol, acetone, methanol, n-heptane, acetonitrile (chromatographically pure, Merck, germany); sodium chloride (analysis)Pure, shanghai test tetrahhelv chemical limited); polymer solid phase extraction cartridge HLB column (Oasis, 200mg, 6mL) (activated with 6mL methanol, 6mL water in sequence before use); c ₁₈ Column (CNW, 500mg, 3 mL); florisil column (CNW, 1g, 6 mL); the water is ultrapure water; the reagents used in other experiments were analytically pure except for the special instructions.

And (3) standard substance: fenpropathrin racemate (CAS number: 39515-41-8, purity ≥ 98.4%, Germany Dr Ehrenstorfer GmbH). Fenpropathrin enantiomer: (-) -fenpropathrin and (+) -fenpropathrin (purity more than or equal to 97%, Shanghai Duolu Biotech Co., Ltd.).

1.2 preparation of Standard stock solution and working solution

1.2.1 Standard stock solutions of the racemate

Accurately weighing 0.01g (accurate to 0.1mg) of fenpropathrin racemate standard substance, accurately metering the volume to a 10mL volumetric flask by using isopropanol, and preparing 1.0g/L racemate standard stock solution.

Standard intermediate solution of fenpropathrin racemate: a defined amount of the standard stock solution of the racemate was aspirated accurately and diluted with n-heptane/isopropanol (9: 1, v/v) to 20.0mg/L of the standard intermediate solution.

1.2.2 enantiomeric Standard stock solutions

Respectively and accurately weighing 0.01g (accurate to 0.1mg) of (-) -fenpropathrin and (+) -fenpropathrin standard products, dissolving the standard products by using isopropanol, and fixing the volume to a 10mL volumetric flask to prepare 1.0g/L enantiomer standard stock solution.

Mixed standard working solutions of two pyrethrin enantiomers: accurately transferring a certain amount of standard stock solutions of (-) -fenpropathrin and (+) -fenpropathrin enantiomers respectively, and gradually diluting the stock solutions to a series of standard working solutions of 1.0, 2.0, 4.0, 10.0 and 20.0mg/L by using n-heptane/isopropanol (9: 1, v/v).

1.3 sample pretreatment

1.3.1 sample extraction

Weighing 5g (accurate to 0.01g) of a sample in a 50mL centrifuge tube, adding 20mL acetonitrile, homogenizing and extracting, adding 3.0 g of sodium chloride, uniformly mixing by vortex, centrifuging at 4000 r/min for 5min, and transferring supernatant to a concentration bottle; adding 20mL acetonitrile into the lower layer residue, extracting for 1 time repeatedly, mixing 2 times of supernatant, concentrating with rotary evaporator to near dry, dissolving with 10mL acetonitrile/water (1: 1, v/v), and purifying.

1.3.2 purification

And (3) putting the solution to be purified in an activated HLB column, loading the activated HLB column, leaching with 5mL of water, discarding the leacheate, draining, eluting with 10mL of acetone, collecting the eluent, drying the eluent in a water bath at 40 ℃ by nitrogen blow-drying till the eluent is nearly dry, adding 1mL of n-heptane/isopropanol (9: 1, v/v) to dissolve to a constant volume, filtering the constant volume solution through a 0.22-micron filter membrane, and measuring.

1.4 chromatographic conditions

A chromatographic column: CHIRALPAK AD-3(150 mm. times.3.0 mm, 3 μm); mobile phase: a is CO ₂ B is methanol; gradient elution procedure: 0 to 0.2min (3% B), 0.2 to 0.21min (3% to 10% B), 0.21 to 2min (10% B), 2 to 2.5min (10% to 3% B), 2.5 to 3min (3% B). And (3) system backpressure: 17.2 MPa; the detection wavelength is 230 nm; the flow rate is 1.5 mL/min; the column temperature is 31 ℃; the sample size was 5. mu.L.

2 results and discussion

2.1 selection of detection wavelength

And after scanning by a PDA detector, extracting an ultraviolet spectrogram of the fenpropathrin enantiomer standard solution from the chromatogram. As shown in FIG. 2, the absorption peaks are obvious at 203nm, 230nm and 275nm, wherein the absorption at 203nm is strongest, the sensitivity is relatively high, but the absorption of interferents is also strong at the wavelength; the absorption at 230nm is strong, and interference peaks at the positions of the fenpropathrin enantiomer peaks are few; the absorption at 275nm is lowest. In comprehensive consideration, for the detection of the fenpropathrin compound, the detection with the wavelength of 230nm which has higher absorbance and less impurities is more advantageous, so the 230nm is selected as the detection wavelength in the experiment.

2.2 optimization of the chromatography column

The chiral stationary phase based on amylose-tri (3, 5-dimethylphenyl carbamate) and cellulose-tri (3, 5-dimethylphenyl carbamate) is two types of chromatographic separation stationary phases which are most widely applied, has good chiral recognition capability and resolution capability, and is complementary to each other in the aspect of chiral recognition capability ^[21] . CHIRALPAK AD-3(150mm in book) is selected in the experiment3.0mm and 3 μm, the filler is amylose-tris (3, 5-dimethylphenylcarbamate), CHIRALPAK OJ-H (100mm × 4.6mm, 5 μm, cellulose derivative chiral column, spherical silica gel coated with chiral polymer (amylose or fiber derivative) on the surface, CHIRALPAK IC (100mm × 4.6mm, 5 μm, silica gel surface cross-linked with cellulose-tris (3, 5-dichlorophenylcarbamate) and Acquity Trefoil CEL1(150mm × 3.0mm, 2.5 μm, cellulose-tris (3, 5-dimethylphenylcarbamate)) to totally 4 kinds of chiral separation chromatographic columns for the two fenpropathrin enantiomers, the results show that the chromatographic peaks of the two fenpropathrin enantiomers completely overlap when the chiral chromatographic columns IC and CEL1 are used for separation, and when the chiral chromatographic columns OJ-H are used for separation, chromatographic peaks of two fenpropathrin enantiomers can realize certain separation, but the separation degree is poor, the full separation of base lines cannot be realized, and the chromatographic peak shape is obviously widened; when the chiral AD-3 chromatographic column is used for separation, the separation degree is good, and the chromatographic peak shape is sharp (figure 3). Therefore, in the experiment, the AD-3 chiral chromatographic column is selected to separate the fenpropathrin enantiomer.

2.3 selection of System backpressure

UPC ² CO in supercritical state ₂ As a mobile phase, the viscosity and the density of the mobile phase can be effectively changed by controlling the back pressure of the system in the experiment process, so that the dissolving capacity and the elution capacity of the mobile phase are adjusted. The viscosity and density of the mobile phase will increase as the back pressure of the system increases. Due to CO ₂ CO at a pressure of more than 7.38MPa and a temperature of more than 31 DEG C ₂ The supercritical state is reached. Therefore, the experiment examines the influence of 10.3, 12.1, 13.8 and 17.2MPa 4 system back pressure on the separation of two fenpropathrin enantiomers. As shown in fig. 4, as the experiment gradually increased the system back pressure, the retention time of the target was advanced and the peak shape became sharper. Under 4 conditions, the chromatographic peak shapes of the two fenpropathrin enantiomers are optimal when the system back pressure is 17.2 MPa. Considering the highest recommended system backpressure for the AD-3 chiral chromatography column, 17.2MPa was chosen as the optimal system backpressure for this study.

2.4 different constant volume reagents

Using 5 UPCs ² Conventional constant volume testPreparation: the 10mg/L alpha-cypermethrin enantiomer is resolved by methanol, ethanol, acetonitrile, isopropanol and n-heptane, and the result shows that the chromatographic peak shape is the best by using n-heptane. Considering that the dissolving capacity of n-heptane is poor when n-heptane is used as constant volume liquid in the subsequent sample pretreatment step, so that the recovery rate of fenpropathrin enantiomer is reduced, the experiment adopts a mixed solution of n-heptane and isopropanol. Meanwhile, the experiment investigates the influence of the mixed solution of n-heptane and isopropanol with different proportions on the chromatographic peak shape of the fenpropathrin. As shown in FIG. 5, the peak shape of (-) -fenpropathrin became gradually sharp and the peak shape of (+) -fenpropathrin became gradually inferior as the proportion of isopropyl alcohol increased. And finally, taking the chromatographic peak shape and the dissolving capacity of the target compound into comprehensive consideration, and finally determining n-heptane/isopropanol (9: 1, v/v) as the volume-fixed reagent in the experiment.

2.5 resolution of racemic Standard

The method established by the invention is adopted to carry out resolution and determination on the purchased fenpropathrin racemate standard substance. As shown in figure 6, the separation effect of the two fenpropathrin enantiomers is good, the effective resolution is realized within 1.4min, the separation degree is 1.7, and the requirement that R is more than or equal to 1.5 for complete separation is met ^[22] . According to the retention time sequence of chromatographic peaks, the method sequentially comprises the following steps: (-) -fenpropathrin, (+) -alpha-cypermethrin. Comparison with literature ^[1 ， ^2] The reported HPLC method has short analysis time and higher separation degree. According to the drawn standard curve, the content of two fenpropathrin enantiomers in 20.0mg/L of standard intermediate solution of 1.2.1-section fenpropathrin racemate is calculated by adopting an external standard quantitative method, wherein the content of (-) -fenpropathrin is 9.3mg/L, and the content of (+) -fenpropathrin is 10.7 mg/L. Content ratio of (-) -fenpropathrin to (+) -fenpropathrin in fenpropathrin racemate and literature ^[2] The reported ratios for separation by HPLC are consistent.

2.6 optimization of purification conditions

Experiment compares HLB ^[23-25] 、C ₁₈ ^[26] And Florisil ^[27] And the like, and the purification effect of the solid phase extraction column of different types on the fruit and vegetable paste sample extraction solution is obtained. In apple paste, strawberry paste, and tomato paste without fenpropathrinAdding two fenpropathrin enantiomer standard solutions into the product, homogenizing and extracting with acetonitrile for 2 times, concentrating, drying, re-dissolving, and purifying with 3 different solid phase extraction columns. The experimental result shows that when Florisil column is adopted for purification, the (-) -fenpropathrin has an interference peak, and the recovery rate is 29.2%; when the HLB column is adopted for purification, the average recovery rate of the two fenpropathrin enantiomers can reach more than 95.5 percent. Repeatability ratio C determined using HLB column samples ₁₈ Good column, consistent with the phenomenon reported in the literature ^[23] Therefore, the experiment finally selected an HLB solid phase extraction column as the purification column.

2.7 methodological considerations

2.7.1 Linear Range and quantitative limits

Fenpropathrin enantiomer series standard working solutions of 1.0, 2.0, 4.0, 10.0 and 20.0mg/L in section 1.2.2 are selected, measured according to optimized chromatographic conditions, and a standard curve is drawn by taking the corresponding peak area as an ordinate (Y) and the mass concentration of the standard solution as an abscissa (X) to perform linear regression, as shown in Table 2. The standard substance is added into a blank sample of the fruit and vegetable paste without fenpropathrin, the measurement is carried out according to an optimized method, and the quantitative Limit (LOQ) of the method is calculated by taking the signal-to-noise ratio (S/N) as 10 to obtain that the LOQ of the (-) -fenpropathrin and the LOQ of the (+) -fenpropathrin are both 0.2 mg/kg. In the linear range listed in Table 2, the linearity is good and the correlation coefficient (r) is good ² ) Are both greater than 0.9992.

TABLE 2 Linear Range, Linear equation, correlation coefficient and quantitation Limit for fenpropathrin enantiomers

2.7.2 recovery and precision

The method of adding standard solution into the blank sample of the fruit and vegetable paste without fenpropathrin is adopted to carry out the measurement of the addition recovery rate and the precision of the method, the addition levels of the (-) -fenpropathrin and the (+) -fenpropathrin are respectively 0.2, 0.4 and 2.0mg/kg, the parallel measurement is carried out for 6 times, the standard addition recovery rate and the RSD are calculated, and the result is shown in the table 3. Recovery of two target compoundsThe yield ranged from 80.6% to 105%, and the RSD (n ═ 6) ranged from 2.6% to 7.7%. The recovery and precision are in accordance with SANTE/12682/2019 ^[28] The method can meet the analysis requirements of apple puree, strawberry puree and tomato puree samples, and can be used for detection of daily analysis.

Table 3 spiking recovery and relative standard deviation of 2 fenpropathrin enantiomers in apple, strawberry, tomato puree samples (n ═ 6)

2.8 testing of actual samples

In order to examine the effectiveness and the practicability of the invention, the established method is applied to detect two fenpropathrin enantiomers in 30 randomly extracted samples of commercial apple puree, strawberry puree and tomato puree (wherein the apple puree is 10 parts, the strawberry puree is 6 parts and the tomato puree is 14 parts). The results show that two fenpropathrin enantiomer components are detected in 1 part of tomato paste sample, wherein the content of (-) -fenpropathrin is 0.21mg/kg, and the content of (+) -fenpropathrin is 0.24mg/kg (see figure 7), the situation and the literature are the same ^[2] Reports that the proportion of (-) -fenpropathrin and (+) -fenpropathrin in the fenpropathrin racemate of industrial products is basically consistent.

3 conclusion

The invention establishes a method for separating and measuring two fenpropathrin enantiomer residues in fruit and vegetable puree (apple puree, strawberry puree and tomato puree) of main infant complementary food by using an ultra-high performance combined phase chromatography. Extracting with acetonitrile, purifying with HLB column, separating with CHIRALPAK AD-3 chiral chromatographic column, and supercritical CO extracting ₂ Methanol as mobile phase, gradient elution and external standard method for quantification. The limit of quantification is 0.2mg/kg, the range of recovery rate by adding standard is 80.6-105%, and RSD is 2.6-7.7%. The method is adopted to measure the fenpropathrin enantiomer residues in 30 fruit and vegetable paste samples purchased from the market, and the detected amount is 0.21mg/kg-0.24 mg/kg.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention, and is provided in the accompanying drawings. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined in this disclosure may be implemented in other embodiments without departing from the spirit or scope of the disclosure. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

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Claims

1. The method for rapidly determining fenpropathrin enantiomer residues in the fruit and vegetable paste by the ultra-high performance phase-combination chromatography, wherein the two fenpropathrin enantiomers are (-) -fenpropathrin and (+) -fenpropathrin, and the method is characterized by comprising the following steps:

1) sample extraction

Weighing 5g of sample, accurately weighing the sample to 0.01g, adding 20mL of acetonitrile into a 50mL centrifuge tube, carrying out homogeneous extraction, adding 3.0 g of sodium chloride, carrying out vortex mixing, centrifuging at 4000 r/min for 5min, and transferring supernatant into a concentration bottle; adding 20mL of acetonitrile into the lower residue, repeatedly extracting for 1 time, combining 2 times of supernate, concentrating to near dryness by using a rotary evaporator, adding 10mL of acetonitrile: water =1: 1(v/v) dissolved, to be purified;

2) purification

Placing the liquid to be purified in an activated HLB column, loading the liquid, then leaching with 5mL of water, discarding the leaching solution, draining, eluting with 10mL of acetone, collecting the eluent, drying the eluent in a water bath at 40 ℃ by nitrogen drying to be nearly dry, adding 1mL of n-heptane/isopropanol =9: 1(v/v) for dissolving and volume fixing, filtering the volume fixing liquid through a 0.22 mu m filter membrane, and waiting for detection;

3) determination of chromatographic conditions

A chromatographic column: CHIRALPAK AD-3, 150mm X3.0mm, 3 μm; mobile phase: a is CO ₂ B is methanol; gradient elution procedure:

0-0.2 min, 3% volume ratio B, 97% volume ratio A;

0.2-0.21 min, 3-10% of volume ratio B, and 97-90% of volume ratio A;

0.21-2 min, 10% volume ratio B, 90% volume ratio A;

2-2.5 min, 10-30% of volume ratio B and 90-70% of volume ratio A;

2.5-3 min, 3% volume ratio B, 97% volume ratio A;

and (3) system backpressure: 17.2 MPa; the detection wavelength is 230 nm; the flow rate is 1.5 mL/min; the column temperature is 31 ℃; the sample size is 5 mu L.

2. The method for rapidly determining fenpropathrin enantiomer residues in fruit and vegetable paste by the ultra-efficient phase-combination chromatography method according to claim 1, which is characterized in that the preparation method of the raceme standard stock solution is as follows: accurately weighing 0.01g of fenpropathrin racemate standard substance to be accurate to 0.1mg, accurately metering the volume to a 10mL volumetric flask by using isopropanol, and preparing 1.0g/L of racemate standard stock solution.

3. The method for rapidly determining fenpropathrin enantiomer residues in fruit and vegetable paste by the ultra-high performance phase-combining chromatography method according to claim 2, which is characterized in that standard intermediate solution of fenpropathrin racemate: a quantity of the standard stock solution of the racemate was accurately aspirated, diluted with n-heptane/isopropanol =9: 1(v/v) to 20.0mg/L of the standard intermediate solution.

4. The method for rapidly determining fenpropathrin enantiomer residue in fruit and vegetable paste by ultra-high performance combined phase chromatography according to claim 1, which is characterized in that the preparation method of the enantiomer standard stock solution is as follows: respectively and accurately weighing 0.01g of (-) -fenpropathrin and 0.1mg of (+) -fenpropathrin standard substance, dissolving the (-) -fenpropathrin and the (+) -fenpropathrin standard substance by using isopropanol, and fixing the volume of the solution to a 10mL volumetric flask to prepare 1.0g/L enantiomer standard stock solution.

5. The method for rapidly determining fenpropathrin enantiomer residue in fruit and vegetable paste by the ultra-high performance combined phase chromatography method according to claim 4, characterized in that the mixed standard working solution of two fenpropathrin enantiomers: accurately transferring a certain amount of (-) -fenpropathrin and (+) -fenpropathrin enantiomer standard stock solutions respectively, and gradually diluting to series of standard working solutions of 1.0, 2.0, 4.0, 10.0 and 20.0mg/L by using n-heptane/isopropanol =9:1 (v/v).

6. The method for rapidly determining fenpropathrin enantiomer residues in fruit and vegetable paste by the ultra-high performance phase-combining chromatography as claimed in any one of claims 1-5, wherein the quantitative limit of the two fenpropathrin enantiomers is 0.2mg/kg, the linear range is 1.0-20mg/L, the linear correlation coefficient is greater than 0.9992, the recovery rate ranges from 80.6% to 105% under the standard addition levels of 0.2, 0.4 and 2.0mg/kg 3, and the relative standard deviation is 2.6% to 7.7%.