Detection of pesticide paraquat (PQ) is of considerable significance
to ensure food safety, and its rapid and on-site detection is still
a challenge. Aimed at the ion characteristics of PQ, an “enrichment
and detection” strategy was proposed to improve the sensitivity
through electrostatic attractions, and the ion characteristic of probes
was adopted to increase the portability through avoiding aggregation-caused
quenching effects in the paper strips. Herein, a novel anion-functionalized
ionic liquid (IL) probe with a large conjugated plane and rich π-electrons
([Fluo][P66614]2) was designed as a fluorescent
and colorimetric dual-channel probe to sensitively and rapidly detect
trace amounts of PQ in vegetables and the environment. The proposed
probe exhibited good linearity with a detection limit of 64.0 nM in
the PQ concentration range of 0.3–7.0 μM (fluorometry)
and 0.1 μM in that of 0.1–8.0 μM (colorimetry),
respectively. In addition, it displayed a rapid fluorescence quenching
response from green to dark (<5 s) and excellent anti-interference
(among 23 other pesticides) due to dual effects of electrostatic attraction
and π–π stacking. Most importantly, the lipophilic
IL probe could be applied in real vegetables and environmental samples
with a satisfying recovery rate of 98–103% and assembled into
a handy paper strip that achieved the visual semiquantitative detection
of PQ. This ionic probe provides a feasible approach for rapidly and
conveniently detecting PQ for ensuring agricultural and food safety
and opens a new avenue to detect ion-responsive analytes in real complex
samples by an “enrichment and detection” strategy.