Analytica Chimica Acta 523 (2004) 49–52 Solid-phase fluorescence spectroscopy for the determination of acetylsalicylic acid in powdered pharmaceutical samples Altair B. Moreira, Iara L.T. Dias 1 , Graciliano Oliveira Neto, Elias A.G. Zagatto 2 , Lauro T. Kubota ∗ Instituto de Qu´ ımica, Universidade Estadual de Campinas, Caixa Postal 6154, CEP 13083-971, Campinas SP, Brazil Received 23 January 2004; received in revised form 1 June 2004; accepted 1 June 2004 Available online 10 August 2004 Abstract A rapid, simple and rugged procedure without requiring any prior sample treatment was developed for the determination of acetylsalicylic acid (ASA) in tablets formulations by solid-phase fluorescence spectroscopy. The method was carried out on powdered samples, consisting of an active substance dispersed in lactose, maize starch, talc and magnesium stearate. Previous knowledge of the sample bulk composition is needed for proper application of the method. Wavelengths for maximum excitation and emission were 288 and 318 nm, respectively, and the fluorescence intensity was linear with ASA concentration within the 50–170 mg g -1 range. Detection and quantification limits were 2.2 and 7.3 mg g -1 , and the analytical frequency was 200 h -1 . For a typical sample, the relative standard deviation of results was estimated as 2.3% (n = 10). Accuracy was assessed by comparing the analytical results obtained with the proposed method with those related to a reference method recommended by British Pharmacopoeia: no differences between the methods were found at the 95% confidence level. © 2004 Elsevier B.V. All rights reserved. Keywords: Solid-phase analysis; Fluorescence spectroscopy; Acetylsalicylic acid; Non-destructive analysis 1. Introduction Acetylsalicylic acid (ASA, trade-name aspirin) was orig- inally prepared in 1853 when Gerhardt [1] reacted acetyl chloride with salicylic acid. ASA is used as analgesic against less intense pains; it is a soft and excellent antipyretic seda- tive [2]. Anti-coagulating effects of the aspirin [3] as well as some respiratory, depressive [4] and anxiety [5] effects caused by ASA have also been extensively pointed out. Several analytical techniques have been proposed for ASA determination, and chromatography [6–9], spectropho- tometry [10–13], electrochemistry [14–19] and spectroflu- orimetry [20,21] should be highlighted. Generally, ASA is not directly determined, and previous hydrolysis is carried out in order to convert ASA to salicylate that is further de- termined [22,23]. In a recent review focusing on analytical ∗ Corresponding author. Tel.: +55 37883091; fax: +55 37882987. E-mail address: kubota@iqm.unicamp.br (L.T. Kubota). 1 Present address: Universidade São Francisco, Bragança Paulista SP, Brazil. 2 Present address: Centro de Energia Nuclear na Agricultura, Univer- sidade de S. Paulo, Piracicaba SP, Brazil. applications of biosensors for salicylate determination [24], it was emphasized that a high consumption of reagents and a long time for analysis are inherent to most of the reported procedures. Moreover, the need for sample preparation prior to the determination makes them cumbersome thus less attractive for large-scale analyses. As a large number of samples should be assayed for quality control in e.g., chemical and pharmaceutical industries, simpler procedures performed in a shorter time are preferred. In this way, an- alytical procedures without requiring the use of chemicals and/or steps of pre-treatment become a good alternative. As an alternative to the traditional techniques, near- infrared (NIRS) [25] and Raman [26] spectroscopy have been used for ASA determination in the solid matrix. However, quantitative determinations with these techniques are feasible only by applying chemometric algorithms, especially with regard to NIRS that usually refers to low-resolution spectra. Fluorescence spectroscopy in the UV–vis region can be exploited to perform the measurements directly in the solid matrix [27]. To date, however, this strategy has been scarcely applied, mainly in relation to solid samples of pharmaceuti- 0003-2670/$ – see front matter © 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.aca.2004.06.011