Collection of samples in passivated canisters is widely used for analysis of trace volatile organic compounds in air because a preconcentration step is usually required prior to analysis. Sample integrity can be compromised by deterioration or artifact formation during storage and preconcentration. A laboratory-tested portable gas chromatograph (PGC) equipped with a highly-sensitive photoionization detector (PID) offers the advantage of near real-time data without preconcentration, but its limitations as a field-portable instrument must be recognized. The paper presents data produced simultaneously by the Canister/TO-14 method and PGCs. They were obtained in U.S. and overseas field studies, at industrial, hazardous waste, and roadway sites. Field results suggest that a combination of canister and PGC methods offers a synergistic approach to source assessment measurements.