This study established a method for the determination of pyrroloquinoline quinone (PQQ) disodium salt, a newly approved food ingredient in China, in foods using centrifugal ultrafiltration as a novel pretreatment technique combined with high performance liquid chromatography (HPLC). Ethylenediaminetetraacetic acid disodium (EDTA-2Na) solution was used as a stabilizing agent in sample extraction. After purification by centrifugal purification, chromatographic separation was accomplished on a RD-C₁₈ column (4.6 mm × 150 mm, 5 μm) with gradient elution using a mobile phase consisting of tetrabutylammonium bromide-potassium dihydrogen phosphate mixed solution and acetonitrile. Detection was carried out using a photodiode array detector. The calibration curve showed good linearity within the concentration range of 0.0400–10.0 mg/L with a determination coefficient of 0.9998. The limit of quantitation (LOQ) was 1.0 mg/kg for liquid samples and 4.0 mg/kg for soy sauce, semi-solid, and solid samples. The recoveries from spiked samples ranged from 82.1% to 103.3% with a relative standard deviation (RSD) ranging from 0.7% to 2.5%. This method was characterized by high sensitivity, simple operation, rapidity and accurate and reliable quantification, and suitable for the quantitative detection of PQQ disodium salt in various food matrices. This research effectively addresses the shortcomings of existing methods for detecting PQQ disodium salt in foods and provide strong technical support for the routine supervision of PQQ disodium salt in various food matrices.

We designed and synthesized novel haptens to produce monoclonal antibodies (mAb) against vitamin B₆ (VB₆). A group-specific mAb (2F9) that recognized pyridoxine (PN), pyridoxamine (PM), and pyridoxal (PL) was prepared using a homologous strategy with 50% maximal inhibitory concentration (IC₅₀) values of 106.60, 250.57, and 400.11 ng/mL, respectively. Based on this, a gold nanoparticles (AuNPs)-based immunochromatographic strip (ICS) test was established for the detection of VB₆ in energy drinks and B-vitamin complex tablets. The developed ICS test results could be semi-quantitatively evaluated by the naked eye within 10 min, and displayed the visual limit of detection (vLOD) values of 250, 500, and 1,000 ng/mL for PN, PM, and PL, respectively. For quantitative analysis, the results obtained by strip reader, with calculated LOD values for PN, PM, and PL were 14.10, 55.58, and 56.25 ng/mL, respectively. Commercial energy drinks and B-vitamin complex tablet samples were detected by the strips and the results were confirmed with high-performance liquid chromatography. Overall, the developed AuNPs-based immunochromatographic sensor was suitable and promising for the group-specific recognition and rapid detection of VB₆ in fortified foods and dietary supplements.