Analytica Chimica Acta 488 (2003) 193–202 Determination of carbaryl and carbofuran in fruits and tap water by -cyclodextrin enhanced fluorimetric method Natalia L. Pacioni, Alicia V. Veglia ∗ Instituto de Investigaciones en F´ ısico Qu´ ımica de Córdoba (INFIQC), Departamento de Qu´ ımica Orgánica, Facultad de Ciencias Qu´ ımicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina Received 10 February 2003; received in revised form 6 May 2003; accepted 3 June 2003 Abstract The effect of -cyclodextrin (CD) and hydroxypropyl--cyclodextrin (HPCD) in water solutions on the UV-Vis and fluores- cence spectra of carbaryl (1-naphthyl-N-methylcarbamate, CY) and carbofuran (2,2-dimethyl,2-3-dihydro-7-benzofuranyl- N-methylcarbamate, CF) was investigated. Host–guest interactions were observed by UV-Vis and spectrofluorimetry and the association constants for the 1:1 complexes (K A , mol -1 dm 3 ) with CD and HPCD were determined. The values obtained were 190 ± 10 and 123 ± 7 mol -1 dm 3 for CF and 350 ± 50 and 644 ± 53 mol -1 dm 3 for CY, respectively. The values of the fluorescence quantum yield ratios (φ complexed /φ free ) were 1.24 ± 0.01 with CD and 1.310 ± 0.007 with HPCD for CY, but much higher for CF being 7.0 ± 0.1 with CD and 9.3 ± 0.4 with HPCD. The limits of detection (LOD) for the fluorimetric determination under the better conditions were 14.5 ng cm -3 for the complex CF:CD and 1.94 ng cm -3 for the complex CY:CD in water, with notable improvement specially in the case of CF. We observed higher analytical sensitivity with the cyclodextrins (CDs) in presence of alcohols but not better LOD. The method is rapid, simple, direct and sensitive and the recovery of CY and CF was found to be between 100 and 112% in fruits and 97 and 109% in tap water. The allowed level of carbamates in banana can be detected by the proposed method. © 2003 Elsevier B.V. All rights reserved. Keywords: Carbamate pesticides; Carbaryl; Carbofuran; Fluorimetric determination; Cyclodextrin 1. Introduction The study of organized systems has proved to be very useful for analytical purposes [1,2]. These micro- heterogeneous systems can be classified into molec- ular aggregates (micelles, vesicles, monolayers, etc.) and polymolecular species (polysilicates such as ze- olites, polysugars such as cyclodextrins, polyethers such as crown ethers) [3]. The association of small molecules with these systems form supramolecular ∗ Corresponding author. Tel.: +54-351-4334170/4334173; fax: +54-351-4333030. E-mail address: aveglia@dqo.fcq.unc.edu.ar (A.V. Veglia). species with properties frequently different from those of the free compound in solution [4]. Several photochemical and photophysical studies investigate the effect of cyclodextrins on luminescent properties of different substrates [3,4]. In some cases, a remarkable increase of these properties have been found and these have analytical applications [5,6]. Taking advantage of this effect, we developed a sen- sitive analytical method for the determination of or- ganic compounds that are of interest in biological [7] and pharmaceutical [8] areas. In this paper, we show that the inclusion of carba- mate pesticides in CDs produces a significant increase in the fluorescence and these can be applied to the 0003-2670/03/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0003-2670(03)00701-3