We have developed a new method for the simultaneous analysis of CFC-11, CFC-12, N2, and Ar in water that allows field samples, collected in copper tubes and locked gas-tight, to be transported and stored for several weeks. In the laboratory the gases are extracted in a vacuum system and frozen onto cold traps. CFCs are measured with a GC-ECD, and N2 and Ar are measured with a GC-TCD. Detection limits are 0.007 pmol kg-1 for CFC-11, 0.017 pmol kg-1 for CFC-12, and 0.89 μmol kg-1 for N2 and Ar. The reproducibility of replicate samples with modern CFC concentrations (1σ) lies within ±1.8% for CFC-11, ±1.5% for CFC-12, ±0.6% for N2, and ±0.8% for Ar. The oxygen demand and anoxic degradation rates of CFCs in the copper tube samplers were determined with lake water. At room temperature (22 °C), the oxygen demand is 14.3 ± 7.6 μmol kg-1 d-1, and the CFC-11 anoxic degradation rate is 0.0026 ± 0.0006 pmol kg-1 d-1. For CFC-12, no anoxic degradation was detected within 200 days.