Rapid diagnosis of diquat and paraquat poisoning: A dual approach using colloidal gold immunochromatographic assay and hydrophilic interaction liquid chromatography

Accurate diagnosis and treatment in poisoning cases necessitate the monitoring of diquat and paraquat concentrations. This study presents a competitive colloidal gold immunochromatographic assay (GICA) strip for qualitative detection, alongside hydrophilic interaction liquid chromatography with ultraviolet detection (HILIC-UV) for quantitative assessment. Both methods underwent rigorous validation. The GICA strip achieved a detection limit of 20 ng/mL and demonstrated no cross-reactivity with glyphosate, deltamethrin, or dichlorvos in spiked serum samples. A compliance rate of 100 % confirmed its repeatability, validated by ten quality control samples at a concentration of 200 ng/mL. HILIC-UV exhibited a detection limit of 0.2 μg/mL and excellent linearity for paraquat and diquat in serum and urine across a range of 0.2-6.4 μg/mL (r² > 0.99). Accuracy ranged from 86.4 % to 111.4 %, with relative standard deviation (RSD) below 10.8 %. Sigma metrics for quality control samples varied from 4.47 to 6.09, establishing a 1-3 s/2/3-2 s/R-4s internal quality control scheme (n = 3, r = 1). A total of 24 patient specimens were subjected to dual testing with HILIC-UV and GICA strips. Among these, 21 samples from 17 patients tested positive, while three patients with confirmed glyphosate, deltamethrin, and dichlorvos poisoning tested negative, indicating complete consistency. Of the positive results, 11 patients were diagnosed with paraquat poisoning, and six with diquat poisoning, both of which significantly impair liver, kidney, and coagulation functions. Integrating GICA for rapid qualitative assessment with HILIC-UV for quantitative analysis enhances the identification of diquat and paraquat poisoning, making it particularly suitable for emergency diagnostics.