The effect of fish matrix on colloidal gold immunochromatographic assay of antibiotics: The source of interference and removal method

Abstract

The matrix effect is a serious problem for the immunoassay of antibiotic residues, which greatly restricts its real application in fishery products as well as other foodstuffs. Till now the related information on the colloidal gold immunochromatographic assay (GICA) is still limited. Therefore, five species of fish as samples, and the interference of main matrix components on the analysis of ciprofloxacin was investigated. Some water-soluble proteins were demonstrated to have significant affluence on GICA. Moreover, magnesium is also an important source of the matrix interference was revealed for the first time, and its interaction with some immunoglobin (Ig)G was assumed to be a possible reason for this. Based on these results, corresponding approaches for elimination of the interference were also explored. The matrix interference was fully eliminated and the sensitivity of GICA was increased about 8 times for the quantitative analysis of ciprofloxacin via acid pre-treatment followed by pH adjustment.