Extraction, Preconcentration and Spectrophotometric Determination of Ethylene Glycol in Antifreeze Samples

Aims: Using a simple and sensitive spectrophotometric method for the indirect determination of ethylene glycol by Malaprade reaction. The method was based on the extraction and preconcentration of iodine.

Place and Duration of Study: Samples: Antifreeze samples were purchased from markets (Erbil, Kurdistan region, Iraq), between April 2011 and August 2011.

Methodology: A method was developed for the determination of ethylene glycol (EG) in antifreeze samples. The method was based on the oxidation of EG with excess potassium periodate in slightly acidic medium; then, extraction and preconcentration of iodine was formed from the reaction of remained periodate with iodide. The decrease in the absorbance of extracted iodine is used to monitor the reaction spectrophotometrically at 515 nm.

Results: The optimum reaction conditions and other analytical parameters were evaluated. Beer’s law is obeyed in the concentration range of 0.2–10 µg/ml (R= 0.9963) and 7.0–36 µg/ml (R= 0.9964) with detection limits of 0.08 µg/ml. The effect of interfering species on the determination is described.

Conclusion: Through the proposed method, a sensitive, low cost, selective, accurate and precise method has been described for the determination of ethylene glycol in antifreeze samples with no interferences from antifreeze additives.