aThe standard mixture was added at eight concentration levels (0.14 – 27.33 μg/L, n = 4) to 500 μL of plant extract obtained from 20 mg of the mixture of rice leaf, rice root, tomato leaf, tomato root, potato leaf and Arabidopsis leaf. The spiked extracts were subjected to SPE and LC-MS/MS analysis as described in Methods part with and without subsequent drying/reconstitution step. 3.3 μL of SPE eluate was injected in UPLC.
b The SPE eluates were dried completely under nitrogen stream and reconstituted in 40 μL acetonitrile. After addition of 40 μL 0.3 mmol/L aq. ammonium formate, the samples were transferred to glass vials and 3.3 μL of solution was injected in UPLC.