7000A GC-QQQ Applications Pesticides in Foods (3)
This application demonstrates • Lack of cross-talk in the Agilent 7000A Triple Quad GC/MS • Benefits of a GC/QQQ in MRM mode over a GC single Quad MS in SIM mode • Ability of Agilent 7000A to achieve excellent sensitivity for pesticides in a difficult matrix such as ginger.
Cross Talk Test • The following test has been designed to demonstrate the lack of cross talk in the Agilent 7000A Triple Quad GC/MS system. • Cross talk or ion ghosting can be a source of error in quantitation. It is the result of a precursor ion entering the collision cell when product ions from the previous reaction monitord are still present. • Inject on column a very high concentration of 3 pesticides (1 ng), chlorpyrifos, parathion and cyanazin. These pesticides co-elute under our multi-residue method at 13.5 minutes. • The following ion traces show no cross talk even at these very high concentrations injected!
1.0 ng Chlorpyrifos on column 314→258 314→286 314→189 314→109 314→225 314→81 Chlorpyrifos
1.0 ng Parathion on column 291→109 291→81 291→189 291→286 225→189 225→225 Parathion
1.0 ng Cyanazin on column 225→189 240→225 225→258 225→286 225→109 225→81 Cyanazin
GC-QQQ MRM vs Single Quad SIMDetamethrin in Garlic 5.0ppb Deltamethrin 30ppb Deltamethrin GC-QQQ Results SIM results on a Single Quad MS It clearly demonstrates that GC-QQQ has much higher sensitivity in MRM mode than a single quadrupole in Selected Ion Monitoring (SIM) mode
GC-QQQ MRM vs Single Quad SIMOmethoate in Garlic 40 ppb Omethoate (R.T 9.705min) It looks good, but we can’t confirm it because the ion ratios are distorted seriously 10 ppb Omethoate. With excellent S/N at this low level it is easy to confirm presence confirm. GC-QQQ removes matrix interference and give more reliable confirmation
Garlic MRM TIC (Black) vs Ginger MRM TIC (Red) Ginger Matrix is more complex than Garlic
Garlic MRM vs Ginger MRM 5.0ppb Omethoate MRM results in Garlic (black and green) and Ginger (red and blue) Although ginger is a very difficult matrix, GC-QQQ successfully eliminate the matrix interference, and omethoate has better S/N value (RMS=64) in ginger than in garlic (RMS=20)
Garlic MRM TIC (Black) vs Ginger MRM TIC (Red) Let’s look at another time segment
Garlic MRM v.s Ginger MRM 5.0ppb Bromopropylate MRM results in Garlic (blue and red) and Ginger (green and brown) Although MRM TICs are much different, the baselines are almost identical for Bromopropylate in ginger and garlic, S/N is 733 (RMS, ginger) and 283 (RMS, garlic) respectively.