Lateral flow immunochromatographic assay for rapid detection of dichlorvos residue in fruits and vegetables

Abstract

Dichlorvos (DDVP), a widely used yet environmentally hazardous organophosphate pesticide, necessitates rapid field monitoring due to increasing regulatory restrictions. In this study, we firstly present a gold-nanoparticle-based lateral flow immunochromatographic assay (LFIA) employing a highly specific anti-DDVP monoclonal antibody for onsite DDVP detection within 20 min. The optimized LFIA exhibited exceptional analytical performance, with limits of detection spanning 16 μg/kg to 108 μg/kg across six fruit and vegetable matrices-all below the established maximum residue limits in foods. Method validation with spiked fruit and vegetable samples showed recovery rates of 87.3-109.4 % and 89.2-103.3 %, respectively, with coefficients of variation below 8.3 % and 7.9 %, respectively, confirming the accuracy and precision of the assay. Notably, LFIA exhibited good agreement with standard GC-MS/MS analysis when applied to 144 authentic samples, further validating its reliability for real-world applications. This LFIA offers key advantages including portability, cost-effectiveness, and compatibility with regulatory thresholds, making it an ideal alternative to conventional instrumental methods for routine pesticide residue screening in food safety supervision settings.

Keywords: Dichlorvos; Food safety; Immunoassay; Lateral flow immunochromatographic assay; Rapid detection.

Scheme 1

(A) Preparation process of GNP-mAb immunoprobe; (B) Schematic diagram of LFIA for the detection of DDVP in fruits and vegetables

Fig. 1

Characterization of GNPs and GNP-mAb immunoprobe. (A) Transmission electron microscopy images of GNPs; (B) Daylight photographs of GNPs solutions with different storage periods; (C) UV–vis absorption spectra of GNPs and GNP-mAb; (D) Zeta potentials of GNPs and GNP-mAb.

Fig. 2

Optimization of LFIA. (A) effect of the pH value represented by 0.10 M K₂CO₃ volume in 1 mL GNPs; (B) and (C) optimization of mAb concentration of GNP-mAb immunoprobe and coating antigen concentration through checkboard test; Effect of analyte dilution buffer: the type of analyte dilution buffer (D), the ionic strength of analyte dilution buffer (E), the pH of analyte dilution buffer (F).Note: different small letters (a–e) indicate the value of T/C or inhibition rate significantly different (P < 0.05); *** indicates an extremely significant difference (P < 0.001).

Fig. 3

Dose-dependent LFIA calibration curve for DDVP (A), cross-reaction of the LFIA with dichlorvos and its analogs (B). Note: *** indicate the value of inhibition rate extremely significant difference (P < 0.001).

Fig. 4

The organic solvent tolerance of LFIA: methanol (A), acetonitrile (B), acetone (C), ethyl acetate (D). Note: different small letters (a ∼ e) indicate the value of T/C or inhibition rate significant difference (P < 0.05).

Fig. 5

Matrix-matched calibration curves for DDVP: apple (a), banana (b), grape (c), pooled fruit sample (d), kale (e), tomato (f), cabbage (g), pooled vegetable sample (h).

Fig. 6

The accuracy and precision of LFIA for DDVP detection in vegetable and fruit: measured level (A); recovery rate (B); coefficient variation (CV) (C).