Simultaneous determination of trace metal ions in industrial wastewater based on UV-vis spectrometry

A novel method combining with continuous wavelet transform and ratio spectra derivative is proposed for simultaneous determination of copper, cobalt and nickel in industrial wastewater by UV-vis spectrometry, without separation step. The derivative calculation by continuous wavelet transform (CWT) using Haar wavelet function is found suitable for noisy signals. The ratio derivative value is measured at zero-crossing wavelength. The linear ranges of calibration graphs are up to 3 mg /L for copper, cobalt and nickel. The root mean squared error of prediction (RMSEP) for copper, cobalt and nickel is 0.073, 0.064 and 0.131, respectively. The mean relative deviations of copper, cobalt and nickel are all less than 5%. The results indicate that the proposed method is rapid, inexpensive, and more accurate than partial least square method. Therefore, it is suitable for analyzing overlapping spectra in their mixtures.