Detection of monobasic, straight-chain saturated fatty acid (octadecanoic C18:0) in CCl<sub>4</sub>, based on the thermal lens effect after excitation by CO<sub>2</sub> laser radiation at 934.9 cm<sup>-1</sup> is described for the first time. The achieved limit of detection (LOD=0.3%) is comparable to that of the transmission infrared technique. Possibilities for further improvements in sensitivity and detection limit are also discussed.
Mladen Franko, Dane Bicanic, Zoltáan Bozóki, and Henk Jalink, "Dual-Beam Thermal Lens Measurement of Condensed-Phase Sample at CO2 Laser Wavelengths: Detection of Octadecanoic Acid in Carbon Tetrachloride," Appl. Spectrosc. 48, 1457-1460 (1994)