Flow injection colorimetric method using acidic ceric nitrate as reagent for determination of ethanol

Area of Science:

• Analytical Chemistry
• Spectrophotometry

Background:

• Ceric ammonium nitrate is known for qualitative ethanol analysis, forming an unstable colored complex.
• Accurate and precise quantitative determination of ethanol is crucial in various applications, including beverage analysis.

Purpose of the Study:

• To develop a simple, precise, and interference-resistant flow injection (FI) colorimetric method for ethanol determination.
• To validate the developed method for analyzing ethanol content in alcoholic beverages.

Main Methods:

• A flow injection system was utilized, incorporating a gas diffusion unit with a PTFE membrane.
• Ethanol diffused across the membrane into an acceptor stream containing ceric ammonium nitrate in nitric acid.
• The resulting red-colored product was quantified spectrophotometrically at 415 nm using an LED-based colorimeter.

Main Results:

• The method demonstrated a linear relationship between peak height and ethanol concentration in the range of 0.1-10.0% (v/v) (r(2)=0.9993).
• A low detection limit of 0.03% (v/v) was achieved.
• The gas diffusion membrane effectively minimized interferences.

Conclusions:

• The developed FI colorimetric method offers a simple and precise approach for ethanol determination.
• The method was successfully applied to analyze ethanol in alcoholic beverages and validated against gas chromatography.