Device for in-situ collection of a gaseous reaction product from a polishing slurry as a workpiece, such as a semiconductor wafer, is being polished with the slurry, including a probe capable of being placed in contact with the slurry, the probe having a channel for transmitting the gaseous reaction product to an analyzer, a first hydrophobic membrane for allowing passage of the gaseous reaction product from the slurry to the channel, and means for directing a carrier gas through the channel.

An apparatus is described for detecting the presence of a gaseous chemical produced during a chemical-mechanical polishing operation. The apparatus includes a catalytic converter, a reaction chamber and a light sensor. The catalytic converter, heated to about 800.degree. C. converts the chemical to a different chemical product. The reaction chamber produces an excited species; the pressure in the reaction chamber is maintained sufficiently low to substantially avoid collisional deactivation of t...