Time saving sample prep for the analysis of 54 pesticide & aflatoxin residues in Cannabis by LC-MS/MS

Presented at NACRW 2017
Kavinda De Silva1, Tami Nguyen1
1 Molecular Testing Labs, Vancouver, WA 98684

Introduction

Pesticide analysis of cannabis leaves and finished goods is becoming increasingly important as many states are legalizing it for medicinal and recreational purposes. Dosing methods include smoking/vaporizing and edibles but cannabis is still a Schedule 1 illegal drug and therefore have no FDA testing guidelines. Trace levels of pesticides can be incurred during cultivation or inhaled from dried pesticides on the cannabis. This study evaluates the sample preparation aspect for LC-MS/MS analysis of a 50+ analyte panel of pesticides, fungicides and aflatoxins. QuEChERS was used to extract the analytes from the cannabis flowers, followed by centrifugation and Thomson Standard Filter Vial for sample clean-up.

Equipment:

  • Sciex 6500 QQQ Mass Spectrometer
  • Shimadzu LC-30AD Pumps
  • Run Time: 15 minutes
  • Flow Rate: 0.5 mL/min
  • Injection Volume: 12 µL
  • Column: Kinetex C18, 5µm, 3mm x 150mm
  • Mobile Phase A: 0.1% FA in Water
  • Mobile Phase B: 5mM Ammonium Formate, 0.1% Formic Acid in MeOH
  • Centrifuge
  • Thomson Standard|FV® 0.2µm PTFE (p/n 35530)*
  • Thomson 48 position Vial Filter Press (p/n 35015-476)

*For some autosamplers it is important to adjust the needle depth of your autosampler when using Thomson filter vials to improve the reproducibility of injections

Sample Preparation of Cannabis Flowers

  1. Weigh out 0.25g of the flower into a 50mL conical.
  2. Add 7g of QuEChERS
  3. Add 15mL of 1% Acetic Acid in Acetonitrile
  4. Vortex for 30 minutes
  5. Centrifuge for 5 minutes
  6. Transfer 400µL into the outer shell of p/n 35530
  7. Add 4µL of ISTD
  8. Partially depress the plunger and vortex
  9. Ready to analyze

Results

20+ compounds were extracted from cannabis flower with excellent recoveries utilizing a modified QueChERS method. The linear range for all the aflatoxins and ochratoxins are 0.5-50ng/mL; while the other analytes are 1.0-100ng/mL. Excellent linearity (see Table 2) and good recovery was achieved for all the compounds.

Table.1Shows the LOQ, linear range, % CV, r2 and accuracy for each analyte
AnalyteLOQ (ng/mL)Linear Range (ng/mL)% CVr2 Value% Accuracy
Abamectin Group 111- 100< 14.60.993293.4 - 105.5
Abamectin Group 211- 100<25.40.9880693.6 - 103.4
AFLATOXIN B2 10.50.5 - 50<3.30.9983793.7 - 105.7
AFLATOXIN B2 20.50.5 - 50<4.90.9983394.0 - 104.6
AFLATOXIN G2 10.50.5 - 50<5.00.9982993.1 - 105.2
AFLATOXIN G2 20.50.5 - 50<5.40.998393.7 - 104.9
AFLATOXIN B1 10.50.5 - 50<3.90.9980592.2 - 105.9
AFLATOXIN B1 20.50.5 - 50<4.00.9978992.0 - 106.4
AFLATOXIN G1 10.50.5 - 50<4.20.9985394.1 - 104.6
AFLATOXIN G1 20.50.5 - 50<4.50.9982793.8 - 105.1
Bifenthrin 111- 100<7.90.9969992.6 - 105.6
Bifenthrin 211- 100<6.20.9970492.8 - 105.3
Chlormequat 111- 100<1.40.9959387.3 - 111.0
Chlormequat 211- 100<4.50.9951286.6 - 111.3
Daminozide 111- 100<1.90.9630366.0 - 131.6
Daminozide 211- 100<4.50.9951265.5 - 131.7
Dichlorvos 111- 100<7.20.9936986.0 - 112.4
Dichlorvos 211- 100<7.20.9937186.1 - 112.8
Imidacloprid 111- 100<4.90.9990497.4 - 101.3
Imidacloprid 211- 100<5.50.9988797.5 - 101.6
Malathion A 111- 100<4.30.9957486.9 - 108.7
Malathion A 211- 100<3.70.9941684.5 - 111.4
Myclobutanil 111- 100<3.50.9980891.6 - 105.2
Myclobutanil 211- 100<4.80.9977391.0 - 106.2
OCHRATOXIN A 10.50.5 - 50<8.60.9723767.4 - 120.0
OCHRATOXIN A 20.50.5 - 50<18.50.9676467.2 - 121.2
Paclobutrazol 111- 100<5.70.9948186.6 - 109.5
Paclobutrazol 211- 100<3.80.9946985.6 - 109.6
Permethrin, cis- 111- 100<6.60.9981395.5 - 103.2
Permethrin, cis- 211- 100<6.50.9978293.6 - 102.8
Permethrin, trans- 111- 100<8.10.9972392.9 - 102.9
Permethrin, trans- 211- 100<7.30.9969491.8 - 105.2
Piperonyl butoxide 111- 100<8.40.9952393.2 - 106.3
Piperonyl butoxide 211- 100<8.90.9952693.1 - 106.3
Propiconazole 111- 100<3.80.9975990.1 - 105.4
Propiconazole 211- 100<2.80.9972289.6 - 106.7
Pyrethrins Cinerin I 111- 100<13.00.9977998.6 - 101.9
Pyrethrins Cinerin I 211- 100<20.50.9949496.4 - 103.3
Pyrethrins Cinerin II 111- 100<8.30.9965190.3 - 105.5
Pyrethrins Cinerin II 211- 100<12.70.9935188.2 - 110.2
Pyrethrins Jasmolin I 111- 100<12.90.9970294.6 - 103.7
Pyrethrins Jasmolin I 211- 100<21.50.9944996.2 - 103.5
Pyrethrins Jasmolin II 111- 100<22.70.9935593.8 - 103.3
Pyrethrins Jasmolin II 211- 100<10.00.9975194.5 - 103.7
Pyrethrins Pyrethrin I 111- 100<17.60.9962697.4 - 101.7
Pyrethrins Pyrethrin I 211- 100<5.00.9990696.4 - 102.4
Pyrethrins Pyrethrin II 111- 100<3.20.9985392.9 - 104.2
Pyrethrins Pyrethrin II 211- 100<38.30.9831991.9 - 106.9
Spinosyn A 111- 100<4.00.9991395.2 - 102
Spinosyn A 211- 100<3.20.9993196.1 - 103.0
Spinosyn D 111- 100<3.90.9989794.9 - 103.2
Spinosyn D 211- 100<5.40.998794.8 - 103.4
Spiromesifen 111- 100<16.60.9922395.8 - 105.0
Spiromesifen 211- 100<13.80.9945795.4 - 104.1
Uniconazole 111- 100<4.70.9977491.1 - 104.8
Uniconazole 211- 100<8.00.9966789.5 - 105.5
Table.2% recovery of a subset of the analytes in Table 1
AnalyteRE MIX (PPB)Spike Conc. (ppb)% Recover
Abamectin8.121081.2%
AFLATOXIN B24.84596.9%
AFLATOXIN G24.96599.1%
AFLATOXIN B14.89597.9%
AFLATOXIN G14.92598.4%
Bifenthrin8.361083.6%
Chlormequat9.381093.8%
Daminozide8.741087.4%
Dichlorvos9.431094.3%
Imidacloprid8.781087.8%
Malathion A10.0010100.0%
Myclobutanil9.621096.2%
Naled8.231082.3%
OCHRATOXIN A4.58591.6%
Paclobutrazol9.591095.9%
Permethrin, cis-8.801088.0%
Permethrin, trans-8.801088.0%
Piperonyl butoxide10.0210100.2%
Propiconazole9.941099.4%
Pyrethrins Cinerin I9.641096.4%
Pyrethrins Cinerin II9.431094.3%
Pyrethrins Jasmolin I8.991089.9%
Pyrethrins Jasmolin II9.981099.8%
Pyrethrins Pyrethrin I9.091090.9%
Pyrethrins Pyrethrin II9.511095.1%
Spinosyn A8.271082.7%
Spinosyn D8.391083.9%
Spiromesifen9.971099.7%
Uniconazole9.371093.7%

Conclusion

Using a modified QuEChERS approach on difficult matrices allows for many compounds to be included in multiresidue pesticide screens that would have otherwise been excluded due to matrix suppression or false negative results. This modified QuEChERS – Filter Vial method saves time, reduces solvent waste and cost over the traditional approach, QuEChERS – SPE. This validated method for the compounds in Table 2 has good linearity and recovery without having to use more expensive time consuming clean-up techniques. This approach is an extremely cost effective way to ensure problem analytes on difficult matrices can be included in a screen. The Thomson Standard Filter vials save time and money when replacing SPE and traditional syringe filtration techniques.

Thomson Instrument Company is not affiliated with Molecular Testing Labs, SCIEX, Phenomenex Inc., Shimadzu Corporation or their products

Title

Time saving sample prep for the analysis of 54 pesticide & aflatoxin residues in Cannabis by LC-MS/MS

Description

Pesticide analysis of cannabis leaves and finished goods is becoming increasingly important as many states are legalizing it for medicinal and recreational purposes. Dosing methods include smoking/vaporizing and edibles but cannabis is still a Schedule 1 illegal drug and therefore have no FDA testing guidelines. Trace levels of pesticides can be i...

PDF Application

Product Used in Application

Standard|Filter Vial - PTFE 0.2µm

Pre-Split Septum, Green Cap

pn#35530-200

Related Products

© 2021 Thomson |
Solutions At Work™

LinkedIn