Precautions for determining copper by BCO photometry
Thread Content
When using the BCO (bis(oxalodihydrazone)) photometric method to determine copper, it works well for comparing sample pairs, but the results obtained on the second day do not match. Which classmate has done this? Please give some advice.
1. Bis**oxalodihydride forms stable blue complexes with copper ions in a buffer solution composed of ammonium chloride and ammonia at a pH of around 9. The absorption curve of this complex was measured, and the maximum absorption wavelength λmax was determined to be 603.7 nm. The absorbance of standard copper ion solutions was measured at this wavelength; the data obtained were analyzed using Origin 6.0 software to generate a standard curve. The linear regression equation is: A=1.0×10^-3+0.01268x; the correlation coefficient γ is 0.9983, with P<0.0001 (n=4). When the copper ion concentration ranges from 0.10 to 20.00 mg/L, there is a linear relationship between absorbance and the concentration of copper ions. 2. This analytical method can be used for routine monitoring in copper-containing wastewater treatment facilities in industrial and mining enterprises. Its accuracy, reproducibility, and error levels all fall within the ranges specified by the **standard methods for water quality analysis. Based on the principles outlined above, it seems that factors such as pH value, color development time, and instrument stability can affect the results; these are just my personal opinions