Monoclonal antibody-based solvent tolerable indirect competitive ELISA for monitoring ciprofloxacin residue in poultry samples

Figures & data

Figure 1. The synthesis procedure of CIP–cBSA immunogen through NHS active ester method.

Figure 2. Ultraviolet absorbance spectra for CIP, cBSA and CIP–cBSA.

Figure 3. Optimised standard icELISA inhibition curve for CIP. Data were obtained by averaging three independent curves, each run in triplicate.

Table 1 Cross-reactivities of related FQ analogues in the CIP immunoassay.

Analogues	IC50 (ng/mL)	CR (%)
Ciprofloxacin	0.56	100
Norfloxacin	0.73	76.7
Enrofloxacin	0.74	75.6
Pefloxacin	0.91	61.5
Enoxacin	1.89	29.7
Sarafloxacin	2.28	24.6
Ofloxacin	3.24	17.3
Lomefloxacin	4.87	11.5
Marbofloxacin	5.71	9.8
Danofloxacin	>5600	<0.01
Flumequine	>5600	<0.01

Figure 4. Effects of pH in assay buffer (A) and NaCl concentrations (B). Each solid symbol represents the mean of three replicates. Insets indicate the fluctuation of A_max/IC₅₀.

Figure 5. Effects of acetonitrile (A) and methanol concentrations (B) on the icELISA inhibition curve. Insets indicate the fluctuations of A_max/IC₅₀ (y-axis) as a function of solvent concentration (x-axis). Each value represents the mean of three replicates.

Figure 6. Correlation between the icELISA and the confirmatory LC–MS/MS method in authentic poultry samples (n=18). The regression curve equation was depicted as follows: (A) in chicken, y=0.9831x+0.3207, R²=0.9411; (B) in duck, y=0.9802x+1.0263, R²=0.953; (C) in geese, y=0.9546x+1.2643, R²=0.894.