Determination of hydroxamic acids by direct spectrophotometry of colored complex in acidic solution

An improved spectrophotometry of hydroxamic acids was evaluated. A synthetic aromatic hydroxamic acid for flotation was directly determined without any extraction in the solution of appropriate acidity. The introduction of ethanol made the process more stable. The characteristic absorption peak of the soluble complex at the wavelength of 525 nm was sensitive to being detected. The relationship between the absorbance and the concentration was in accordance with Lambert–Beer’s law in the range 0–120 mg/L, with a related coefficient of 0.9997. Compared with other determinations, this method considerably reduces the period and manipulation under the precondition of accuracy, so that it could be an available determination for hydroxamic acids.