The conjugated antigen of ganoderic acid A was synthesized by the active ester method using bovine serum albumin as a carrier and was used as an immunogen to immunize rabbits according to the immunization procedure to obtain the polyclonal antibody against the conjugated antigen. After analyzing the titer and target of the polyclonal antibody, an indirect competitive-enzyme linked immunosorbent assay (ic-ELISA) for ganoderic acid A was established. The results showed that the polyclonal antibody included idiotypic antibodies targeting three regions of the conjugated antigen, with a total titer of 1:78125, and a titer of 1:3125 for specific anti-ganoderic acid A antibody. The detection limit of ganoderic acid A was 0.3 μg/L, and the median inhibitory concentration was 4.0 μg/L. The linearity range of this method was 0.6–27.3 μg/L. The inter-batch coefficient of variation was less than 10%, and the recoveries for spiked samples were between 82.9% and 118.6%. The results of determination of 22 commercial samples of Ganoderma lucidum powder showed that there was a significant difference in ganoderic acid A contents among different brands. The correlation coefficient between the results of this method and those obtained by high performance liquid chromatography (HPLC) was 0.972. The results showed that ic-ELISA was feasible for the determination of ganoderic acid A. This method can provide an auxiliary scheme for the quality control of related products in the G. lucidum health product market.

Ochratoxin A (OTA) in samples was captured and concentrated by immunoaffinity chromatography (IAC) and detected by enzyme-linked immunosorbent assay (ELISA). The anti-OTA monoclonal antibodies used in IAC and ELISA came from different clone strains, belonging to different idiotypes, and there were differences between their selectivity for binding to OTA targets. The combined use of IAC and ELISA could effectively filter out the interference from OTA analogues, thus improving the specificity and sensitivity of immunological analysis. The limit of detection (LOD) for OTA in spiked samples was 0.2 ng/g, the quantification limit was 0.4 ng/g, and the average recovery was 75.9%. Although the recovery of the IAC-ELISA method was slightly lower than that of ELISA, the sensitivity was increased by 60 times. For 49 real samples, the proportion of samples that tested positive by this combined method was 100% consistent with the result of the national standard method, with a missed detection rate of 0%. Therefore, the developed method exhibited significant advantages in accuracy. As a comprehensive immunoassay, this method does not require any large-scale instruments or equipment, and has no strict requirement on the operating environment, thereby making it easy for grassroot laboratories to analyze OTA in samples.