Facile and rapid detection of residual
organic pesticides on the
fruits and vegetables has recently drawn increased attention in the
food safety field. Herein, a surfactant-assisted solvothermal route
with subsequent post-modification was designed for the preparation
of Eu3+-functionated Zn-BDC ultrathin nanosheets (labeled
as Eu3+@Zn-MOF-NS, BDC: 1,4-benzenedicarboxylate) with
the thickness of 5 nm. The as-obtained Eu3+@Zn-MOF-NS could
be homogeneously dispersed in aqueous systems to form a highly-stable
collosol. Under the UV excitation of 325 nm, the as-obtained Eu3+@Zn-MOF-NS displayed red photoluminescence emission of Eu3+ ions, which could be notably quenched by an organochlorine
pesticide, 2,6-dichloro-4-nitroaniline (DCNA), without interferences
from ions, organic small molecules, and other pesticides. The detection
limit and K
sv were 0.17 μM (35 ppb)
and 3.2 × 105 M–1 in the water system,
respectively. Moreover, the present 2D Eu3+@Zn-MOF sensor
was also employed for the detection of DCNA in Chaohu Lake water and
tap water and in apple, cabbage, and pakchoi samples with the relative
standard deviation (RSD) ranging from 4.74 to 9.77%. Further investigations
revealed that the competitive absorption between DCNA and the as-obtained
Eu3+@Zn-MOF-NS resulted in the fluorescence quenching of
the probe.