Analyttca Chtmtca Acta, 214 (1993) 261-274 Elsewer Science Pubhshers B V , Amsterdam 267 Direct determination of benzene in gasoline by flow-injection Fourier transform infrared spectrometry MAxuno Galhgnam, Salvador Gamgues and Miguel de la Guardia Departamento de Qubmca Analittca, Unwemdad de Valence, C/ Dr Molcner 50, 46100 Bugassot, Valencra (Spa& (Recensed 20th July 1992, revised manuscnpt recewed 17th August 1992) A Founer transform mfrared spectrometnc procedure for the automated determmatxon of benzene m gasoline was developed, based on the use of flow-m)ectlon analysis The method permits the direct determmatlon of benzene unthout any pretreatment of samples, w~tb a hnut of detection of 0 02% (v/v> and a relative standard deviation of ca 1% [for five mdependent analyses of a dduted sample contammg a 0 4% (v/v> of benzene] Results found by direct analysis agreed wth those obtamed by off-lme and on-line standard addltlon methods A rapld quality control procedure was developed, based on the on-hne mjectlon of gasohne samples (dduted zyxwvutsrqponmlkjihgfedcbaZ 1 + 9 m hexane) mto a earner stream of a 0 5% (v/v> solution of benzene m hexane, m this instance, the baselme corresponds to the upper hnut tolerated by the European Econonuc Commumty’s law for gasohnes Thus, the mJectlon of dduted samples wth an appropnate level of benzene must provide no peaks or negatnre peaks, whereas those wrth a benzene concentration higher than that tolerated prowde posltlve peaks A senes of real samples were analysed by the proposed procedure and the results obtained were comparable to those given by gas chromatography Kkywor& Flow ln)ectlon, Infrared spectrometry, Benzene, Gasolme The determmatlon of aromatic hydrocarbons m naphthas and motor gasolmes IS necessary m several areas of the petroleum, petrochenucal and related mdustnes [l] Detailed mformatlon on the aromatlc composltlon of fuel mater&, intermediates and commercial products 1s re- quired for process development and quahty con- trol programmes For this purpose, gas chro- matography and other chromatographlc tech- ruques have been extensnrely used [2-lo] In ad- dition, leglslatlon m several countnes hmlts the upper concentration of some hydrocarbons m commerrxl gasolmes For example, the upper Correspondence to M de la Guardia, Departamento de Quirmca Analitica, Umversldad de Valencla, C/ Dr Mobner 50,461OO Bmyassot, Valencla (Spam) lmut tolerated by the European Econormc Com- mumty’s laws for benzene IS 5% (v/v), the nor- mal content of benzene m gasolmes bemg 2 5% <v/v> Thus, m some mstances the determmatlon of a compound 1s required m order to check the quality of the final product The fact that mfrared (IR) spectrometnc tech- niques provide a rapid means for the direct deter- mmatlon of aromatlc compounds [11,12] encour- aged the development of an mexpenslve, rapid and simple method for the direct determmatlon of benzene m gasolmes, based on the use of flow-mjectlon Fourier transform IR (FI-FT-IR) spectrometry The only precedent found m the literature was a standard method of the Amen- can Society for Testmg and Materials WWM) for the IR batch determmatlon of benzene m motor and avlatlon gasolmes [13] 0003-2670/93/$06 00 0 1993 - Elsevler Science Pubhshers B V All nghts reserved