Sensitive detection of trace-level organophosphorus pesticides in fruit juices using a novel pH-responsive fluorescence probe based on 4-(morpholinomethyl) phenyl) boronic acid

A novel pH-responsive fluorescence probe, (4-morpholinomythyl) boronic acid (4-MPBA), was synthesized and employed for the detection of organophosphorus pesticides (OPs) in fruit juices. 4-MPBA was sensitive to pH changes in the range of 3.0–5.8 with R2 of 0.9914, which was based on the inhibitory reaction between OPs and acetylcholinesterase (AChE). The linear range spanned over the range of 0.80–32 μg·L−1 with limits of detection of 0.16–0.24 μg·L−1. This fluorescence assay was utilized for detecting trace-level OPs with satisfactory recoveries (95.73–104.50%) and RSDs of < 6.74%. The total residues of OPs were detected to be 5.50–20.84 μg·L−1 in 12 unfortified juice samples. The experimental accuracy and precision offered by this probe were verified to be satisfactory using a certified reference fruit juice (QC-202005A-1). Thus, we posit that the newly developed fluorescence probe can be satisfactorily applied for daily monitoring of trace OPs in juice matrices.