Photothermal detection methods for capillary liquid chromatography

The advantages of capillary liquid chromatography make it a very attractive alternative to analytical scale high performance liquid chromatography. Unfortunately, instrumental requirements for capillary liquid chromatography are very stringent. This is especially true for the detectors employed which require a volume on the order of one nanoliter for optimum performance. Laser based methods offer the capability to make sensitive measurements while probing very small volumes, making them ideal for capillary liquid chromatography detectors. Two laser based absorption detectors were investigated in order to determine their capability as detectors for capillary liquid chromatography.

A continuous wave argon ion laser based single beam thermal lens detector was shown to be a sensitive detector for nitroaniline compounds separated with an open capillary liquid chromatography column. A photothermal refraction detector employing a tunable excimer pumped dye laser was coupled with slurry packed capillary columns to detect nitrated polycyclic aromatic hydrocarbons. The detectors illustrated the capability of making sensitive absorption measurements within the extremely small volumes associated with capillary liquid chromatography solute bands.