The analysis of salbutamol in swine serum is the more practical basis for large scale surveillance programs in Taiwan. Objectives of the study were to develop a new assay and to compare with a commercially available kit in field test screens. A simple and reliable enzyme-linked immunosorbent assay (ELISA) to monitor the presence of beta-agonist, salbutamol, in 1,358 field samples of swine serum that were collected from local meat markets was described. The method proved to be suitable and sensitive for the detection of beta-agonist residues caused by growth promoting dosage. The limit of detection of the developed ELISA directly performed on diluted serum was 0.25 ng/mL. The application and the results of two ELISA kits (homemade and commercially available) for the screening of salbutamol were presented. For further confirmation, all samples that showed to be ELISA positive for salbutamol residues were analyzed by GC-MS. Adopting 1 ng/mL salbutamol as a cutoff value, the commercial beta-agonist ELISA had a sensitivity of 89.2% and a specificity of 86.7% versus GC-MS at a cutoff of 1 ng/mL. The homemade salbutamol ELISA had a sensitivity of 81.1% and a specificity of 98.6% and gave a low proportion of false-positive rate results. The reliability of the developed kit in terms of the percentage of false-positive rate results is evaluated. In conclusion, a sensitive, specific salbutamol ELISA has been developed that could serve as a rapid screening assay, and the detection of positive samples at the place of sampling can result in more effective control of the illegal use of beta-agonists.

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Florfenicol (FF) is a synthetic antibiotic with a broad antibacterial spectrum and the high therapeutic effectiveness that has been developed specifically for veterinary use. Obviously, FF adulterated in animal supplies is one of essential global concerns. A competitive ELISA for the detection of florfenicol in food of animal origin (swine, chicken, and fish) is described. Influence of immunoconjugate structure on the assay sensitivity and specificity was investigated. The new ELISA showed much lower than the MRPLs for FF at 100-3,000 mg kg(-1) in the European Communities and the sensitivity of our ELISA method was superior to that described in other reports. According to the test preparation record, the limit of detection of the developed ELISA performed on meat species was 0.3 µg kg(-1) (IC50 value 1.9 µg kg(-1)). The method developed permits FF concentrations to be determined in the range 0.3-24.3 µg kg(-1). A low cross-reactivity with florfenicol amine (FFA), thiamphenicol (TAP), and chloramphenicol (CAP) was displayed (16.2%, 9.5%, and 9.4%, respectively). Recovery in different food samples (swine, chicken, and fish) averages between 87-115%. The method can be applied for inspection of animal supplies for trace florfenicol residues.