Determination of various pesticide residues in Chinese cabbage - GC/MS solution

The widespread use of pesticides has played a positive role in the prevention and control of agricultural pests and diseases, but it has also contaminated crops and the natural environment to varying degrees. Many pesticides are stable in nature and are not easily degraded in nature. Some pesticides are directly or indirectly left in vegetables, causing food pollution and endangering human health. Therefore, countries have established stricter pesticide residue limit standards.

Method advantages:

Based on various standards, Dima Technology established a solid phase extraction-gas chromatography-mass spectrometry method for the determination of various pesticide residues in Chinese cabbage. It was extracted with 1% formic acid acetonitrile and added with QuEChERS to extract salt. The fraction is completely separated from the acetonitrile extract, and the extraction environment is at a mild pH value to ensure the stability of the target compound. The extract is purified by a ProElut Carb/NH2 solid phase extraction column, concentrated and analyzed on the machine. Gas Chromatography-Mass Spectrometry for Detection of Pesticide Residues in Chinese Cabbage:

1) It can achieve quasi-deterministic quantification, and the limit of quantification meets the requirements of GB 23200.8-2016 national food safety standard, determination of 500 pesticides and related chemical residues in fruits and vegetables by gas chromatography-mass spectrometry;

2) It has the advantages of simple pretreatment, less loss of recovery rate, obvious purification effect and good method reproducibility, which can be widely used by analysts;

3) Applicable to all provinces and cities for entry and exit, quality inspection, disease control, food and drug inspection, third-party testing institutions, food testing institutions, large food producers, universities and research institutes.

The following is a detailed solution, please refer to!

Determination of Multiple Pesticide Residues in Chinese Cabbage——GC/MS Method

1. Scope of application

This program is applicable to dichlorvos, chlorpyrifos, trifluralin, phorate, α-hexachlorocyclohexane, hexachlorobenzene, dimethoate, β-hexachlorocyclohexane, lindane, pentachloronitrobenzene and ethion , δ-hexachlorocyclohexane, chlorothalonil, chlorpyrifos, diarrhea, methyl chlorpyrifos, methyl parathion, heptachlor, methyl chlorpyrifos, picophos, chlorpyrifos, methyl Pyrimidine, aldrin, malathion, fenthion, dicofol, chlorpyrifos, parathion, pyrimidine, hexachlorocyclohexane, triazole alcohol, procymidone, chlorpyrifos, alpha-endosulfan, chlorine Dan, dieldrin, profenofos, p,p'-DDE, endrin, beta-endosulfan, p,p'-DDD, o, p-DDT, ethion, triazophos, endosulfan Detection of sulfate, p,p'-DDT, phoxim, sulforaphane, cyfluthrin, cypermethrin, fenvalerate, difenoconazole, deltamethrin.

2, standard preparation

(1) Single standard stock solution: Accurately weigh each standard and prepare a standard stock solution of 10 mg/mL with toluene.

(2) Mixing standard stock solution: separately absorb each standard standard stock solution and make a mixed standard stock solution of 10 μg/mL with toluene.

3, extraction

Take 15 g of sample, add 15 mL of 1% formic acid acetonitrile solution, shake for 5 min, add QuEChERS extract salt*, shake for 5 min, cool for 10 min, centrifuge at 8000 rpm for 2 min, take 5 mL of supernatant, and purify.

*QuEChERS extraction salt: 6 g anhydrous magnesium sulfate and 1.5 g anhydrous sodium acetate.

4. Purification - ProElut CARB/NH2 500mg/500mg/6mL (Cat.#:64105)

a activation:

Add 5 mL of acetonitrile: toluene = 3:1, discard the effluent;

b loading:

Adding the liquid to be purified to the column and collecting the effluent;

c elution:

Add 25 mL of acetonitrile to the column: toluene = 3:1, collect the effluent;

d redissolve:

It was distilled to dryness under reduced pressure in a water bath at 40 ° C, and 1 mL of acetonitrile was added and mixed for GC/MS analysis.

5, chromatographic conditions

Column: DM-5MS, 30 m × 0.32 mm × 0.25 μm (Cat. #: 8231)

Inlet temperature: 240 °C

Heating program: initial temperature 70 °C, hold for 2 min, raise the temperature to 150 °C at 25 °C / min, then increase the temperature to 200 °C at 3 °C / min, then increase the temperature to 280 °C at 8 °C / min for 10 min

Carrier gas: helium, column flow rate: 0.54 mL/min

Injection method: split injection

Injection volume: 1.0 μL

Ion source temperature: 230 °C

Interface temperature: 280 °C

Solvent delay: 4 min

Electron Impact Ionization Source (EI): Select ion monitoring mode (SIM), group monitoring is shown in Table 1.

Table 1 Selected ion monitoring group table

aisle

Start time

(min)

End Time

(min)

Selective ion (m/z)

1

5.30

6.00

109,185,79

2

10.10

10.50

158,97,139

3

10.90

12.54

306,264,75,121,183,219,111,284,142,87,125

4

12.55

13.30

219,181,109,237,295

5

13.70

14.90

88,97,125,142,183,109,219,266,124,231,161,119,91,204,123

6

15.70

16.80

286,125,109,263,100,272,265,285

7

17.10

18.80

277,125,109,290,305,66,263,93,173,278,139,111,250,97,197,314,291

8

19.60

20.10

333,318,168,353,81

9

20.60

22.20

112,128,168,283,96,145,85,375,237,272,241,195,339

10

23.00

23.60

79,263,108,246,318,176,97,208,339

11

23.90

25.60

81,263,281,241,195,339,235,165,246,231,97,153

12

25.70

26.70

161,77,387,272,237,235,165

13

28.00

29.50

157,169,141,185,182,121

14

31.70

32.70

163,206,91,181,127

15

33.50

41.86

125,167,225,265,323,181,253,77,93

6, add recycling results

The results of GC-MS detection (addition level 40 μg/kg) of various pesticide residues in Chinese cabbage were added, and the standard amount was 10 μg/mL mixed with 60 μL.

NO.

Compound name

Recovery rate(%)

1

Dichlorvos

101.75

2

Extinction phosphorus

102.64

3

Fluorine

103.09

4

Phosphorus

101.67

5

--å…­å…­å…­

98.02

6

Hexachlorobenzene

75.52

7

Dimethoate

106.54

8

--å…­å…­å…­

100.32

9

Lin Dan

100.62

10

Pentachloronitrobenzene

91.11

11

Acetate

99.85

12

Δ-六六六

104.27

13

Chlorothalonil

86.91

14

Chlorazol

108.64

15

Different rice

105.30

16

Methyl chlorpyrifos

106.76

17

Methyl parathion

102.19

18

Heptachlor

91.70

19

Methyl chlorophosphate

104.59

20

Fly fly phosphorus

103.68

twenty one

Sulphur

104.32

twenty two

Methyl pyrimidine

94.47

twenty three

Aldrin

99.05

twenty four

Malathion

100.76

25

Fenthion

101.18

26

Dicofol

85.11

27

Chlorpyrifos

98.60

28

Parathion

96.39

29

Pyrimidine

106.29

30

Epoxy heptachlor

101.43

31

Triazolol

100.23

32

Procymidone

94.99

33

Killing phosphorus

102.33

34

Alpha-endosulfan

101.30

35

Chlordane

98.14

36

Dield

97.92

37

Profenofos

110.79

38

p,p'-DDE

92.62

39

Endrin

96.39

40

Beta-endosulfan

104.23

41

p,p'-DDD

96.28

42

o, p-DDT

88.44

43

Ethion

99.76

44

Triazophos

107.89

45

Endosulfan sulfate

114.14

46

p,p'-DDT

91.57

47

Phenylphos

105.55

48

Sulfox

100.10

49

Cyfluthrin-1

107.82

50

Cyfluthrin-2

107.00

51

Cyfluthrin-3

117.82

52

Cyfluthrin-4

112.93

53

Cypermethrin-1

107.46

54

Cypermethrin-2

94.22

55

Cypermethrin-3

104.83

56

Cypermethrin-4

87.12

57

Fenvalerate-1

104.35

58

Fenvalerate-2

101.25

59

Difenoconazole

117.17

60

Deltamethrin

91.06

Multiple pesticide residue standards (10 μg/mL) TIC map

Determination of various pesticide residues in Chinese cabbage - GC/MS related product information:

Item number

name

specification

Sample preparation

64105

ProElut ProElut CARB/NH2

500mg/500mg/6mL, 30/pk

30039

FitMax needle filter Nylon

13 mm, 0.22 μm 100/pk

30040

FitMax needle filter Nylon

13 mm, 0.45 μm 100/pk

Standard

For related standard information, please call us.

Column and guard column

8231

DM-5MS

30 m × 0.32 mm × 0.25 μm

HPLC Solvent? Buffer Salt? Ion Pair Reagent

50101

Acetonitrile HPLC grade

4 L

50144

Formic acid HPLC grade

50 mL

General purpose chromatography products

52401B

Bottle holder / blue (spot)

50 holes

52401A

Bottle holder / white (spot)

50 holes

1034

Vial (brown/thread)

2 mL, 100/pk

1035

Sample cap/with pad (already assembled)

100/pk

H87900

GC syringe

5 μL

Red product number #30039, #30040, #1034, #1035 hot promotion