Page 33 - Application Notebook - Solution for Food Safety

P. 33

For LabSolutions Version 5.82 and Later
LC/MS/MS Method Package for Residual Pesticides Ver. 2

Co-Injection Improves the Peak Shapes for Polar Compounds

① No Co-Injection of Water ② Co-Injection of Water
2 µL sample with 40 µL water “sandwich”
(0.5 µL sample, 10 µL water × 4)
Sample
x10 6 x10 6
Air 8.0
3.5
Co-Injection of Water via SIL-30AC Pretreatment Mode 3.0 7.0
6.0
2.5
Samples prepared by the QuEChERS method are typically extracted with 100% 5.0
2.0
acetonitrile. While this approach is effective for most pesticides, it results in 4.0
1.5
poor peak shape and response for highly polar pesticides. To enhance the peak 3.0
1.0 2.0
shape and detection of highly polar pesticides, the acetonitrile extract was
co-injected with a larger volume of water. This technique achieves band 0.5 1.0
compression and delivers a marked improvement in peak shape and response 0.0 0.0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 min 0.5 1.0 1.5 2.0 2.5 3.0 3.5 min
for early eluting compounds, particularly for highly polar pesticides.
A pretreatment program for co-injection is incorporated in the method for 646 MRM Chromatograms for Pesticides spiked into a Tomato Extract
(2 µL sample injection volume)
pesticides.
Note: Co-Injection mode is only supported by the SIL-30AC.
Maintains Stability with Different Matrices
×10 6
5.0 Apple Mint Tomato To assess the robustness of the system, three matrices (apple,
mint and tomato) were spiked with 646 pesticides at 0.05
%RSD 3.7
4.0 mg/kg and repeatedly injected (each matrix sample was
%RSD 3.4 %RSD 3.4 analyzed with 100 repeat injections; the total batch run was
Peak Area Response 2.0 %RSD 3.9 %RSD 3.2 probenazole were selected as representative response
3.0 300 injections). Thiofanox-sulfone, dipropetryn, and
markers with retention times close to four, six, and seven
%RSD 5.4 %RSD 3.6 minutes, respectively. Within a matrix, variance was less than
1.0 %RSD 5.9
%RSD 5.8 5.9%RSD for all compounds.
0.0
0 50 100 150 200 250 300 Although the absolute peak area changes with different food
Injection Number
matrices, the response between injection 1 and injection 100
Thiofanox-sulfone Dipropetryn Probenazole
for two pesticides (probenazole and dipropetryn) within a
Peak Area Response for Three Pesticides Spiked into Apple,
Mint and Tomato Matrix Extracts at 0.05 mg/kg over 72 hours. single matrix has a variance less than 5.7%RSD.
Apple Mint Tomato The new LC/MS/MS Method Package for Residual Pesticides
Ver.2 extends the capability of the LCMS-8000 series in
Probenazole pesticide analysis and creates new opportunities for
expanded pesticide screening programs supported by a
pre-packaged single LC/MS/MS method for 646 pesticides.
1st injection 100th injection 1st injection 100th injection 1st injection 100th injection
Dipropetryn

MRM Chromatograms for Probenazole (Top: Retention Time 5.995 mins) and Dipropetryn
(Bottom: Retention Time 6.999 mins) for Injection 1 and injection 100 Spiked into Apple,
Mint and Tomato Matrix Extracts. The extracts were spiked at 0.05 mg/kg and analyzed over 72 hours.

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