The combination of narrow-bore capillary gas chromatography with bench-top quadrupole mass spectrometric detection was evaluated for the determination of polychlorinated biphenyls (PCBs). The qualitative and quantitative performances of the system are illustrated by several analyses (PCB standards and human milk extracts). Capillary columns with different internal diameters (0.10, 0.18 and 0.22 mm, respectively) were compared for their ability to separate PCB congeners and the analysis time. Short run times (less than 7 min) were sufficient for complete separation of PCB congeners on a 0.10-mm internal diameter (I.D.) capillary column without any loss of resolution when compared with a 0.22 mm I.D. column. Good qualitative and quantitative data acquisition was possible with quadrupole mass spectrometer for run times of 8 min, but incomplete peak reading was observed when run times were reduced to 3-4 min. Selected ion monitoring and dwell times of 10 ms are necessary to obtain detection limits for individual PCB congeners as low as 0.4 pg microl(-1) for standard solutions and 0.2 ng g(-1) fat for milk extracts. By using cold splitless injection, relatively high volumes (1 microl) for narrow-bore capillaries could be injected without any peak distortion.