Development of a micro dual beam fluorometric detector specific for microchip analysis of benzo[a]pyrene and benzo[k]fluoranthene in diesel exhaust particulate samples

We developed a device and some systems for detecting benzo[a]pyrene (B[a]P) and benzo[k]fluoranthene (B[k]F). The device uses a UV light-emitting diode that emits light with a wavelength of 370 nm and a violet laser diode that emits light with a wavelength of 395 nm as excitation light sources. The detection method is based on the following observation: characteristic fluorescence is emitted from both B[a]P and B[k]F, with intensities up to 10 times greater than those from 22 other polycyclic aromatic hydrocarbons (PAHs). The excitation and emission wavelengths for fluorescence from B[a]P and B[k]F are 370 and 429 nm, and 395 and 429 nm, respectively. Further, we calculated their concentrations in diesel exhaust particles by means of two calibration curves determined using a mixture of 24 PAHs. The detection limits of the proposed device with a microchip are 5.58 microg L(-1) for B[a]P and 6.03 microg L(-1) for B[k]F. We applied this method to analyze B[a]P or B[k]F contained in three types of diesel exhaust particles, and the results agreed well with those obtained by liquid chromatography.