Journal of Chromatography A, 871 (2000) 235–241 www.elsevier.com / locate / chroma Short communication Determination of phenolic antioxidants in aviation jet fuel a, a b b * M. Bernabei , G. Bocchinfuso , P. Carrozzo , C. De Angelis a Centro Sperimentale di Volo, Reparto Chimico, Aeroporto Pratica di Mare, 00040 Pomezia, Rome, Italy b Centro Sperimentale di Volo, Reparto Medicina Aeronautica e Spaziale, Aeroporto Pratica di Mare, 00040 Pomezia, Rome, Italy Abstract The world-wide aviation jet fuel used for civil and military aircraft is of a kerosene type. To avoid peroxide production after the refinery process a specific antioxidant additive should be added on fuel. The antioxidants generally used are based on hindered phenols in a range of concentration 10–20 mg / ml. In the present work a specific method to measure the concentration of phenolic antioxidants is shown. The method is based on a liquid chromatographic technique with electrochemical detection. The technique, because of its selectivity, does not require sample pre-treatments. The analysis of a 5–10 ml fuel sample can be performed in less than 10 min with a sensitivity of 0.1 mg/ml and a RSD52.5%. A comparison with another highly selective gas chromatographic technique with mass spectrometric detection with selected ion monitoring (GC–MS-SIM) is reported. The sensitivity of GC–MS-SIM method was 2 mg/ml with a RSD53.1%.  2000 Elsevier Science B.V. All rights reserved. Keywords: Kerosene; Antioxidants; Phenols; Alkylphenols 1. Introduction with detrimental effects on the jet fuel thermal stability [3]. For this reason a specific antioxidant The world-wide aviation jet fuel used for civil and additive should be added after the refining process. military aircraft is of a kerosene type, a development The antioxidants generally used are based on hin- of the illuminating kerosene originally used in gas- dered phenols as 2,6-di-tert.-butylmethylphenol (AO- turbine engines [1]. Aviation turbine fuel, grade Jet 1), 2,4-dimethyl-6-tert.-butylphenol (AO-2) and 2,6- A1, is generally manufactured mainly from straight- di-tert.-butylphenol (AO-3), (Fig. 1) in a range of run kerosene. Straight-run kerosene obtained from concentration 10–20 mg/ml. In the present work a sweet crude oil will meet the requirements of the jet specific method to measure the concentration of fuel specification with some refinery process. One of phenolic antioxidants is shown. The method is based these processes is ‘‘hydrotreating’’ to reduce the on a liquid chromatographic technique with electro- sulphur active compounds present in kerosene to chemical detection (HPLC–ED) [4–7]. The tech- elemental sulphur to obtain a jet fuel with sulphur nique, because of its selectivity, does not require level according to the present directive [2]. This sample pre-treatments. The analysis of a 5–10 ml process generates a peroxidation of some hydro- fuel sample can be performed in less than 10 min. carbons which can originate a rapid deterioration of A comparison with a gas chromatographic tech- nitril rubber and the formation of insoluble deposits nique with mass spectrometric detection in the selected ion monitoring mode (GC–MS-SIM) [8– *Corresponding author. 10] is reported. The internal standard (I.S.) chosen 0021-9673 / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0021-9673(99)01274-1