Collection and separation systems, collection and separation methods, isotope analysis systems, methods of processing samples to analyze .sup.15N, .sup.13C, and .sup.34S, and the like are provided. A system that includes a collection system in gaseous communication with a first device, wherein the collection system is configured to isolate two or more gases of a gaseous sample and configured to introduce each to a second device independently of one another is provided.

The invention provides for the integration of a CO-consuming process, such as a gas fermentation process, with a CO.sub.2 electrolysis process. The invention is capable of utilizing a CO.sub.2-comprising gaseous substrate generated by an industrial process and provides for one or more removal modules to remove at least one constituent from a CO.sub.2-comprising gaseous substrate prior to passage of the gaseous substrate to a CO.sub.2 electrolysis module. The invention may further comprise one or more pressure modules, one or more CO.sub.2 concentration modules, one or more O.sub.2 separation modules, and/or an H.sub.2 electrolysis module. Carbon conversion efficiency is increased by recycling CO.sub.2 produced by a CO-consuming process to the CO.sub.2 electrolysis process.