The quantitative and qualitative aspects of splitless and on-column capillary column injectors for the analysis of environmental extracts for priority pollutants are investigated. Precision data are presented for a wide variety of compounds introduced into a splitless injector by manual and totally automated injection practices. Similar studies are performed using manual injections into an on-column injector. Other studies include capillary system reactivity toward liable analytes, column selection, and the identification of the limitations of current capillary column systems with respect to the analysis of complex extracts. Sufficient experimental evidence is documented to support the need for a unique quality assurance program, not associated with packed column systems.