The behavior of the pulsed infrared laser thermal lens signal is studied for flowing gas samples. Possible sources of decreased TLS signal are discussed including flow rate and cell temperature. The TLS signal is found to be independent of the flow rate at all flow rates studied. It is calculated that absorbances as low as 2.5 x 10-7 in argon and 1 x 10-7 in liquid carbon disulfide should be detectable. The possibilities of using this technique as a chromatography detector for ultratrace amounts of analyte are also discussed.