Chloramphenicol is a broad-spectrum antibiotic, which is widely applied in anti-bacterial infections (Kikuchi et al., 2017; García Lorente et al., 2020). Many studies found that long-term use of cosmetics with added chloramphenicol might cause adverse reactions known as contact dermatitis, manifested as erythema, edema, erosion, itching and burning (Diepgen et al., 2016; Nielsen et al., 2001). Thus, the use of chloramphenicol in cosmetics has been banned in USA, European Union, China, and other countries. However, chloramphenicol is often illegally added by unscrupulous manufacturers to anti-acne cosmetics to provide faster relief of acne and other symptoms. In a recent survey in China, 29 out of 2717 anti-acne cosmetics purchased from markets were detected positive for chloramphenicol (National Medical Products Administration, 2017). A sampling survey in Shanxi Province found that one sample of an anti-acne cosmetics contained chloramphenicol (National Medical Products Administration, 2021). Therefore, there is a need to develop reliable and efficient detection methods for the illegally added chloramphenicol in cosmetics.

Chloramphenicol is commonly measured with high-performance liquid chromatography (HPLC) (Tu et al., 2019), gas chromatography tandem mass spectrometry (GC–MS) (Liu et al., 2014) and LC/MS (Rimkus and Hoffmann, 2017). Those methods were often applied in professional institutes limited by the expensive equipment and complicated operations, which are not suitable for on-site tests. Enzyme-linked immunosorbent assay (ELISA) has been regarded as a rapid and sensitive method. However, ELISA is still not convenient for in situ analysis because of the multiple washing steps and long-time incubation during the assay. Lateral flow immunoassay (LFIA) is appropriate for in situ detections, which is widely used to monitor drug misuses (Fu et al., 2017; Peng et al., 2017). Several studies reported that LFIA could detect illegally added antibiotics in aqueous samples without any pretreatment steps (Alhammadi et al., 2022; Liu et al., 2019). Despite their advantages, the sensitivity of LFIAs is slightly less than that of ELISAs based on the same antibodies. The antibody is the dominant role effecting the sensitivity and specificity of an immunoassay. Effort had been made by different researchers to develop sensitive mAbs against chloramphenicol. A half maximum inhibition concentration (IC50) of most commercial chloramphenicol ELISA kits was approximately 0.2 ng/ml and the hapten used to develop the antibody was proprietary (Biovision, 2023).

The produced high-quality mAb is significantly influenced by hapten design, containing the characteristic similarities with target molecules, the spacer arms structure and the correspondingly linker site (Lu et al., 2011). The diazo-derivative chloramphenicol (Kolosova et al., 2000), chloramphenicol succinate (Kolosova et al., 2000; Chen et al., 2011; Samsonova et al., 2009) and chloramphenicol base (Samsonova et al., 2009) were commonly used to synthesize chloramphenicol haptens. The reported, diazotized chloramphenicol derivatives generated lower potency antibodies than the other haptens-derived antibodies and therefore is not under our consideration. In this study, we synthesized two haptens derived from chloramphenicol base with different spacer arms and chose another reported hapten chloramphenicol succinate to develop mAbs. The aim was to compare and evaluate the effect of hapten structures on antibody quality and select a sensitive and high-titer chloramphenicol mAb to develop LFIA for in situ screening of chloramphenicol in cosmetics.