A gas chromatographic method of analysis for trimethyl and triethyl phosphates was developed that used direct aqueous injection. Automated, cool, on-column injection was investigated because of the large number of samples to be analyzed and the realization that the best inlet system for quantitative high resolution gas chromatography is the non-vaporizing, cool, on-column technique. Automated injection would increase not only sample throughput, but also precision and accuracy. Anticipated problems in the method development were the buildup of salts in the column system from injection of the buffered samples and the loss of flame in the flame ionization detector during the passage of water through the instrument. The trimethyl (TMP) and triethyl (TEP) phosphates are often contaminants or impurities carried over from the synthesis of more complex phosphates. TEP has been identified in the groundwater adjacent to a landfill site. (Copyright (c) 1989 Dr. Alfred Huethig Publishers.)