Abstract: Colloidal gold particles with three different particle sizes of 20, 30 nm and 40 nm were prepared by the sodium citrate method. The colloidal gold particles with various particle sizes were then used to prepare test strips with colloidal gold-labeled anti-chloramphenicol (CAP) monoclonal antibodies. The preparation parameters of these test strips were optimized and their performance was compared. The test strip containing 30 nm colloidal gold particles exhibited a detection limit of 3 ng/mL. However, the detection limits of the test strips containing colloidal gold particles of 20 nm and 40 nm were only 7 ng/mL and 9 ng/mL, respectively. Moreover, the test strip containing 30 nm colloidal gold particles was more stable and sensitive than the other two and could therefore provide a more suitable marker for testing chloramphenicol.

Key words: chloramphenicol, colloidal gold, particle size, test strip