Reverse Flow Injection–Spectrophotometric Determination of Ethylene Glycol in Antifreeze Solutions via Periodate–o-Tolidine Reaction

Abstract

Aims: A reverse flow injection analysis technique was developed for the spectrophotometric determination of ethylene glycol in antifreeze solutions. Place and Duration of Study: Antifreeze solutions were purchased from oil-changers (Erbil, Kurdistan region, Iraq), between April 2011 and August 2011. Methodology: The method based on the inhibition effect of ethylene glycol on the reaction of periodate and o-tolidine in the presence of acetic acid. The decrease of blue meriquinone absorbance with ethylene glycol was used to monitor the reaction spectrophotometrically at 630 nm. Influences of chemical and physical parameters were evaluated. Selectivity of the method and the suitable conditions for sample analysis were investigated. Results: Working on optimized conditions, the detection limit was 10 µg/ml with correlation coefficient of 0.9983. The relative standard deviations observed at 40, 100 and 160 µg/ml were 3.27, 1.81 and 0.80% respectively and the analytical throughput was 52 s/h. Possible interferences that related to the determination of ethylene glycol in antifreeze solutions were studied and the results showed that foreign species caused less than ±5.0% error. Conclusion: Six samples of commercial antifreeze solutions were analyzed according to the developed procedure not presenting any statistical difference in relation to the results obtained by standard method.