Development of a simplified densitometer for the determination of aflatoxins by thin-layer chromatography

A simple, miniaturised and low power consuming (battery, fully semiconducto r based) detector cell (SeBaDeC) was developed for the densitometric measur ement of aflatoxins on TLC plates. A UV-light emitting diode (UV-LED) with a peak emission wavelength of 370 nm was used for fluorescence excitation, while a photo diode with a peak sensitivity of 440 nm in combination with a 418 nm cut-off filter was applied for detecting the fluorescence intensity . The resulting signal was further amplified by means of a commonly used op erational amplifier integrated circuit (OA) and directly converted into a d igital signal with a simple analogue-digital-converter (ADC). This signal w as recorded at the serial (RS232) port of a portable PC and processed with a spreadsheet program. The software used for data recording is freeware and available in its source code, and the long lifetime of the UV-LED (up to 1 0 000 h) permits a maintenance free application of this device. This simpli fied device has shown to be able to detect concentrations of aflatoxins of 1 ng, thus offering a cheap and sensitive alternative to currently availabl e TCL scanners. (C) 2000 Elsevier Science B.V. All rights reserved.