Flow injection spectrophotometric determination of copper, iron, manganese, and zinc in animal feeds using a common manifold

A rapid and simple procedure was developed for the determination of copper, iron, manganese, and zinc in animal feeds using an identical flow injectio n spectrophotometric manifold but different chromogenic reagents and differ ent detection wavelengths, Bis(cyclohexanone)oxalydihydrazone, formaldoxime , 1,10-phenanthroline, and xylenol orange were adopted as chromogenic reage nts for Cu, Min, Fe, and Zn, respectively. Detection conditions such as man ifold parameters, buffer pH, reagent concentration, temperature, and acidit y of sample solution were optimized. Analytical characteristics of the meth od and interference of metal ions commonly present in feeds were studied. B y changing the reagents and detection wavelengths, which can be done quickl y, the proposed low cost flow injection system can determine Cu, Fe, Mn, or Zn in the range of 0.5-10 mg/L with a sampling throughput of 120/h.