Analytical Sciences

Sensitivity Enhancement of Thermal-Lens Spectrometry Using Laser-Induced Precipitation

Dmitry A. NEDOSEKIN,* Werner FAUBEL,** Mikhail A. PROSKURNIN,* and Ute PYELL***

*Chemistry Department, M. V. Lomonosov Moscow State University, Leninskie Gory, GSP-2, Moscow 119991, Russia
**Research Center Karlsruhe, Institute of Technical Chemistry, Water Technology and Geotechnology Division, Karlsruhe 76021, Germany
***Department of Chemistry, University of Marburg, Hans-Meerwein-Strasse, Marburg 35032, Germany

The possibility of thermal lensing of dynamically emerging light-absorbing layers at cell surfaces was investigated. Analyte accumulation at a cell surface determines long-term changes in the thermal-lens signal that was used as a source of analytical information to enhance sensitivity of thermal lensing. Considering the rate of accumulation as an additional analytical signal, we achieved a threefold decrease in the limits of detection for 4-aminoazobenzene to the level of 7 µM in a batch mode with the same level of reproducibility. The details of observed thermal-lens signal behavior in cells are discussed. The possibilities to use thermal-lens detection for 4-aminoazobenzene determination in quartz capillaries in flow mode were discussed and a drastic thermal-lens signal enhancement was discovered. The corresponding limit of detection for 4-aminoazobenzene in a flow mode is further decreased to the level of 3 µM.

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