An analytical method for the determination of histamine using metals and alizarin red S (ARS) reagents by UV-Visible spectrophotometry was developed. Cu(II), Co(II) and ARS were used to form colored complex with histamine. The developed method was used to detect qualitatively and quantitatively the presence of histamine. Absorbance of Cu(II) and Co(II) complex were measured at a maximum wavelength of 505.5 and 567 nm, respectively. Optimization of analytical parameters such as concentration of metals, concentration of ARS, sample solution pH, and optimum time for complex formation were performed. Experimental results showed that the optimum concentration of Cu(II) was 50 ppm, 75 ppm ARS, sample solution pH 6, and 15 minutes optimum time, while the optimum concentration of Co(II) was 125 ppm, ARS was 75 and 50 ppm, sample solution pH 5 and 10 minutes optimum time. Method validation indicated that the coefficient of variation, limit of detection (LOD) (S/N =3), and limit of quantitation (LOQ = 10S/N) of Cu(II) were 0.65%, 8.94 ppm, and 29.82 ppm respectively with a sensitivity of 0.0054 ppm and linearity of 0.9959. Accuracy of histamine determination through Cu-ARS-histamine complex at a concentration of 50, 100, and 150 ppm were 105.7% (RSD = 0.777%, n = 3), 105.06% (RSD = 0.606%, n = 3), and 94.12% (RSD = 0.767%, n = 3), respectively. Meanwhile, the CV, LOD, and LOQ of Co(II) were 0.28%; 2.58 ppm; and 8.6 ppm respectively with a sensitivity of 0.0006 ppm and linearity of 0.9965. Accuracy of histamine determination through Co-ARS-histamine complex at a concentration of 50, 75, and 125 ppm were 98.33%, 95.83%, 93.88%, respectively. The proposed method was successfully applied to the determination of histamine in a fish sample with quantitative recovery; for Cu(II) complex (99.23%) and Co(II) complex (102.62%).
- UV-visible spectrophotometry