ABSTRACT
The indirect competitive enzyme-linked immunosorbent assay(ic-ELISA) and direct competitive enzyme-linked immunosorbent assay(dc-ELISA) were performed for the rapid detection of aflatoxin B_1(AFB_1) in Astragali Radix, Zingiberis Rhizoma Recens, Jujubae Fructus, and Nelumbinis Semen with self-made antigens and antibodies. Different extraction methods were investigated to reduce the matrix effects of different medicinal parts in Chinese herbal medicines. The sensitivity of dc-ELISA method was improved by optimizing the molar ratio of AFB_1 to horseradish peroxidase(HRP). In this study, the sensitivity(IC_(50)) of ic-ELISA and dc-ELISA was 0.046 and 0.023 ng·mL~(-1), with the limit of detection(LOD) of 0.007 and 0.004 ng·mL~(-1), respectively. The detection time was 3 h and 50 min for ic-ELISA and dc-ELISA, respectively. The recovery rates were within the range of 62.96%-104.4%, with RSDs of less than 10%. Confirmed by LC-MS/MS, three positive samples of Nelumbinis Semen were detected from 53 samples. Two ELISA methods established in this study were accurate, rapid and sensitive, and can be used for rapid screening of AFB_1 in Chinese herbal medicines such as Astragali Radix, Zingiberis Rhizoma Recens, Jujubae Fructus, and Nelumbinis Semen. In addition, the advantages and limitations of the two methods were compared and discussed, which can provide a reference for the testing institutions to choose the proper method.
Subject(s)
Aflatoxin B1/analysis , China , Chromatography, Liquid , Enzyme-Linked Immunosorbent Assay , Tandem Mass SpectrometryABSTRACT
Due to the low molecular weight and simple structure, the production of specific antibodies against acrylamide is unavailable. In this study, a novel hapten was synthesized through the derivatization of acrylamide and 4-mercaptophenylacetic acid. The hapten was then coupled to carrier protein and used to immunize New Zealand rabbits. Polyclonal antibody which showed specific binding to the acrylamide derivative ( hapten) was obtained. The antibody was labeled with horseradish peroxidase ( HRP) and used to develop a direct competitive enzyme-linked immunosorbent assay ( dc-ELISA) . The dc-ELISA was used to determine the content of acrylamide derivative, and then transferred to the content of acrylamide. The assay showed an IC50 value of 45. 49 μg/L, a limit of detection of 3. 0 μg/L and the linear range of 9. 2-195 μg/L for acrylamide. The recovery of acrylamide from spiked food sample was determined ranging from 83 . 6% to 112 . 7%. Good correlations between the results of dc-ELISA and standard HPLC-MS/MS were obtained. The proposed dc-ELISA is suitable for the determination of acrylamide in food samples.
ABSTRACT
The labeled compounds, CdTe was combined with anti-fluoranthene antibody, had good dispersion and stability with the fluorescence intensity enhancing. A direct competitive fluorescent immunoassay with CdTe-anti-fluoranthene antibody to detect fluoranthene in water sample in the environment was developed. The result showed that fluoranthene can be determined in the concentration range from 0.1 μg/L to 1000 μg/L with a correlation coefficient of 0.9983, a sensitivity of (IC_(50)) of 12.4 μg/L and a detection limit (IC_(20)) of 13.1 ng/L. Trace environmental pollutant in environmental water samples were successfully determined with a good accuracy and suitability. The recovery was between 95.1% and 111.0%, with relative standard deviation less than 9%.
ABSTRACT
Background: Simultaneous screening of ephedrine with amphetamine or methamphetamine in drug abusers is useful in countries, such as Thailand, that prohibit the use of ephedrine. The lack of an adequate screening test kit suitable for this purpose is a significant obstacle in the detection of ephedrine abusers. A reliable analytical method for the simultaneous detection of amphetamine, methamphetamine and ephedrine is needed. Objective: To develop a process for the detection of amphetamine, methamphetamine and ephedrine by enzyme-linked immunosorbent assay (ELISA), based on the polyclonal antibody and heterology principle. Methods: The 3-aminopropyl (3AP) and 4-aminobutyl (4AB) derivatives of amphetamine (A), methamphetamine (M) and ephedrine (E) were chemically synthesized. They were used for the preparations of immunogens and hapten tracers. Direct competitive ELISA of matrix combinations of antisera and hapten tracers were performed using amphetamine, methamphetamine and ephedrine as the analytes. Only the competitive reactions with specified sensitivity and specificity are selected. Results: The study discovered three assay combinations that demonstrated concentration-dependent competition of analyte (single or multiple). They passed the confirmation test for the cut-off concentration and had no cross-reactivity with other amines or structured related compounds. The assay combinations of 4ABA-Ab with 3APA-PO and 4ABE-Ab with 3APM-PO were specific for the detection of amphetamine with ephedrine and methamphetamine with ephedrine, respectively. The third assay combination of 4ABE-Ab with 3APE-PO was highly specific to ephedrine with negligible cross-reactivity from other structure-related compounds. Direct competitive ELISA of 4ABE-Ab with 3APM-PO has been proven useful in field tests for the detection of methamphetamine in urine samples from Thai truck drivers suspected of drug abuse. Conclusion: By using heterology, these three assay combinations could be used separately or simultaneously for drug abuse screening.