Determination of rhodamine B in capsicol using the first derivative absorption spectrum

Abstract

In this work an analytical method for the determination of rhodamine B in capsicol was developed based on absorption spectrum. The absorption spectra were obtained about the rhodamine B-capsicol mixed solution using spectrophotometer. The experimental results show that the absorption spectra of rhodamine B-capsicol mixed solution have a stable characteristic peak at 555nm, while the first derivative absorption spectrra of the mixed solution have two characteristic peaks, and the position of the characteristic peak shifts blue with the increase of concentration of rhodamine B. Exponential and linear function regression analysis were carried out about the absorbance of characteristic peak and the concentration of Rhodamine B. Then the prediction models of Rhodamine B in capsicol were obtained. The minimum correlation coefficient was 0.9401 and the maximum was 0.9992. In addition, the recovery rate and relative standard deviation (RSD) of each model function were calculated and analysed, respectively. The results show that the exponential function is superior to the corresponding linear function, and the corresponding model function of the first derivative spectrum is superior to the model function obtained from the original spectrum. The best mean recovery rate and RSD of the original absorption spectrum is 106% and 7.658%, while the optimal result of the first derivative absorption spectra is 101% and 2.3453%, respectively. In summary, the analytical model developed allows to detect the rhodamine B in capsicol with good correlation coefficient and reproducibility, and this study provides a new way for the detection of food colorant content.