Abstract:

Based on competitive binding immunoassay, a colloidal gold lateral flow strip for the quantitative detection of
malachite green was developed by reading the absorbance of test (T) and control (C) lines with a test strip reader. Different
concentrations of malachite green standard were detected with the test strip reader at different times of reaction. Three different
detection models were proposed by plotting the absorbance of T line, T/C and T/(T ＋ C) against the concentration of standard,
respectively. At 10 min of reaction, the linear correlation coefficient (R2) between the concentration of standard and the
absorbance of T line was 0.9438 with coefficient of variation (CV, n = 3) of 1.6%–8.2%, whereas the r values for T/C and T/
(T ＋ C) were 0.9811 and 0.9916 and the CV values were 0.4%–3.7% and 0.3%–2.2%, respectively. The T/(T ＋ C) model
exhibited better linearity and smaller CV, and its sensitivity was 3 μg/L.

Key words: malachite green, lateral flow assay, quantitative detection method