title: Assessment of critical points and development of a practical strategy to extend the applicable scope of immunoaffinity column cleanup for aflatoxin detection in medicinal herbs.
abstract: Although extraction methods based on immunoaffinity column (IAC) cleanup have been used to detect aflatoxins in medicinal herbs, they do not yield satisfactory results for all sample matrices. The difficulty arises from the chemical complexity of the herbs, and there is a pressing need to determine which steps in IAC cleanup limit the scope of aflatoxin detection in many different kinds of medicinal herbs. In this work, we found that there were two main factors that severely decreased antibody-antigen recognition and led to serious nonspecific adsorption: (1) high extract acidity and (2) high co-extraction of interfering compounds. We therefore carried out a systematic study to optimize extraction efficiency. We found that dilution of samples in 0.1M phosphate buffer solution (pH 7.8, 2% Tween-20) at a 1:8 dilution ratio mitigated the effect of high acidity, decreased co-precipitation of compounds and nonspecific adsorption, and ameliorated the matrix effect. To validate this finding, and test if our method is widely applicable to in different kinds of herbal materials, we analyzed several representative complex sample matrices including fructus, cortex, and radix with varying extract pH values. The recovery efficiency was generally higher than 70%. We further validated our method by testing a certified reference material, and found that our approach accurately quantified aflatoxin concentration. After validation, we successfully used this method to determine the aflatoxin concentration of real samples. The approach described here could potentially be used to extract aflatoxin from other complex matrices with varying acidity.
authors.affiliation: Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China.
authors.forename: Xiaowen
authors.initials: X
authors.lastname: Dou
authors.affiliation: Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China.
authors.forename: Weijun
authors.initials: W
authors.lastname: Kong
authors.affiliation: Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China.
authors.forename: Congmin
authors.initials: C
authors.lastname: Liu
authors.affiliation: Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China.
authors.forename: Xu
authors.initials: X
authors.lastname: Han
authors.affiliation: Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education, Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing 100193, China. Electronic address: yangmeihua15@hotmail.com.
authors.forename: Meihua
authors.initials: M
authors.lastname: Yang
mesh_terms: D000327:Adsorption; D000348:Aflatoxins / Q000032:analysis*; D002021:Buffers; D011232:Chemical Precipitation; D002846:Chromatography, Affinity / Q000379:methods*; D002851:Chromatography, High Pressure Liquid; D006863:Hydrogen-Ion Concentration; D010946:Plants, Medicinal / Q000737:chemistry*; D015203:Reproducibility of Results; D012996:Solutions; D012997:Solvents; D053719:Tandem Mass Spectrometry
chemical_list: D000348:Aflatoxins; D002021:Buffers; D012996:Solutions; D012997:Solvents
keywords: Aflatoxins; Certified reference material; Immunoaffinity column cleanup; Medicinal herb