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Development of a Simple, Fast, and Quantitative Lateral Flow Immunochromatographic Strip for Folic Acid

Liang, Zu-Pei, Ha, Wu-Zu, Xiao, Zhi-Li, Lei, Hong-Tao, Shen, Yu-Dong, Sun, Yuan-Ming, Wang, Hong, Yang, Jin-Yi, Xu, Zhen-Lin
Food analytical methods 2017 v.10 no.7 pp. 2444-2453
antigens, dietary supplements, dried milk, folic acid, food fortification, food quality, high performance liquid chromatography, immunoaffinity chromatography, inhibitory concentration 50, models, monitoring, nanogold, polyclonal antibodies, screening, variance
Folic acid (FA) is an important B vitamin naturally found in foods and also used in dietary supplements and food fortification. To monitor FA content is important to guarantee food quality and also to prevent its abuse in dietary supplements. In this work, we developed a simple and robust lateral flow immunochromatographic assay (ICA) for the routine screening of FA in food samples. FA was conjugated to carrier protein as immunogen and used to produce specific polyclonal antibody (pAb). The pAb was conjugated with gold nanoparticle and used to develop a lateral flow ICA. After the careful optimization of ICA conditions, the assay showed an IC₅₀ of 51.8 ng mL⁻¹ and linear range from 23.4 to 114.5 ng mL⁻¹ for FA in assay buffer, with the assist of a DY6510 strip reader within 8 min. Using milk powder as a matrix model, after a 15-fold dilution to eliminate matrix effect, the ICA showed intra-assay recoveries from 94.2 to 107.0% with coefficient of variance (CV) below 15% and inter-assay recoveries from 91.4% to 111.3% with CV below 18%. Good agreement was obtained between the results of ICA and ciELISA and standard HPLC. It is an ideal screening tool for the fast monitoring of FA in a simple, fast, and low-cost manner.