ABSTRACT
Discussion of specific instruments or comparisons among the many that suppliers provide, therefore, becomes not only a potentially enormous undertaking, but one of questionable value because of timeliness, i.e., such a discussion would probably be seriously outdated by the time of publication of this monograph. Consequently, instead of attempting to provide specifics about suppliers and their products, it seemed more appropriate in these comments to indicate how suppliers may be identified and associated with the various technologies that the author's have been discussing. Gas chromatographs, which ordinarily would be categorized as laboratory analyzers, may, for example, frequently serve as monitors. They are equipped with automatic sampling valves that are inserted in the process stream, which are then used to extract samples periodically from the stream to inject them into their columns.
