Talanta 64 (2004) 711–715 Determination of formaldehyde in Brazilian alcohol fuels by flow-injection solid phase spectrophotometry Leonardo S.G. Teixeira a,b,∗ , Elsimar S. Leão a , Ala´ ılson F. Dantas a , Helo´ ısa L.C. Pinheiro a,c , Antonio C.S. Costa a , Jailson B. de Andrade a a Instituto de Qu´ ımica—Universidade Federal da Bahia, Campus Universitário de Ondina, 40.170-280-Salvador, Bahia, Brazil b Departamento de Engenharia e Arquitetura—Universidade Salvador—UNIFACS-Av. Cardeal da Silva 132, 40.220-141-Salvador, Bahia, Brazil c Centro Federal de Educação Tecnológica da Bahia—CEFET-BA, Rua Em´ ıdio de Morais S/N, 40.625-650-Salvador, Bahia, Brazil Received 30 January 2004; received in revised form 23 March 2004; accepted 25 March 2004 Available online 19 May 2004 Abstract In this work, a solid phase spectrophotometric method in association with flow injection analysis for formaldehyde determination has been de- veloped with direct measurement of light-absorption in C 18 material. The 3,5-diacetyl-1,4-dihydrolutidine produced from the reaction between formaldehyde and fluoral P was quantitatively retained on C 18 support and the spectrophotometric detection was performed simultaneously at 412 nm. The retained complex was quickly eluted from C 18 material with the eluent stream consisting of a 50% (v/v) ethanol solution. The results showed that the proposed method is simple, rapid and the analytical response is linear in the concentration range of 0.050–1.5 mg L -1 . The limit of detection was estimated as 30 gL -1 and the R.S.D. 2.2% using a sample volume of 625 L. The system presented an analytical throughput of 20 determinations per hour. The method was successfully applied in the determination of formaldehyde in ethanol fuel. © 2004 Elsevier B.V. All rights reserved. Keywords: Formaldehyde; Solid phase spectrophotometric; Fluoral P; Ethanol fuel 1. Introduction Formaldehyde enters the environment from natural sources (including forests fires) and from direct human sources such as fuel combustion, industrial on-site uses, and off gassing from building materials and consumer products. Thus, formaldehyde is uniquely important because of its widespread use and toxicity and it is recognized as one of most important environment pollutant [1]. This compound is widely present in the environment and is classified as “a probable human carcinogen”, identified by the US Environ- mental Protection Agency and International Agency for Re- search on Cancer as a Class 2A carcinogen [2]. Also, it has known irritant properties, such as dermatitis, eye irritation, respiration irritation, asthma, and pulmonary edema [3,4]. Although formaldehyde is not present in gasoline, it is a product of incomplete combustion and is released, as a result, from internal combustion engines. The amount ∗ Corresponding author. Tel.: +55-72-2032568; fax: +55-71-2032712. E-mail address: leonardoteixeira@unifacs.br (L.S.G. Teixeira). generated depends primarily on the composition of the fuel, type of engine, operating conditions and age and state of the vehicle [1,5]. In metropolitan areas, formaldehyde is almost always the predominant aldehyde emitted by automobiles. Meanwhile, there is evidence that the use of oxygenated fuels, including methanol, ethanol and blended fuels, can change the aldehyde profile emissions [5,6]. Brazil is the country that has attempted the large-scale use of alcohol as an automobile fuel by the use of ethanol–gasoline blended fuel (gasohol, mixture of 75% gasoline and 25% anhydrous ethanol). In addition, in Brazil, there are light duty cars exclusively driven using hydrated ethanol as fuel [7] and it is known that formaldehyde con- tamination in hydrated ethanol can be found because this compound can be formed during ethanol production by alcoholic fermentation process [8]. Indeed, it is necessary sensitivity and accuracy analytical methods for determina- tion of this compound in this kind of matrix. Small amounts of formaldehyde are commonly analyzed by spectrophotometric methods [9]. The spectrophotomet- ric determination of formaldehyde with chromotropic acid 0039-9140/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.talanta.2004.03.047