
Keywords: Trace metals; Microanalysis; Box–Behnken; Cu; V; dPKBHdPKBH, di-2-pyridylketone benzoylhydrazone; Cu, copper; V, vanadium; CDTA, 1,2-cyclohexanediaminetetraacetic acid; UV–Vis, ultraviolet–visible; ANOVA, analysis of variance; LOD, limit of detection