Abstract
Programmed temperature operation using a constant-frequency electron capture detector (ECD) has been investigated. There are two causes of the base line drift with the elevation of column temperature. One is the bleed of volatile matter from an injection septum made of silicone polymer, and the other from a packed column. The former was removed by using the septum treated as follows : soaked in toluene, cleaned with ultrasonic wave, and dried at 250°C under reduced pressure of 1 mm Hg. The latter decreased by repeating temperature programing operation. After repeating 20 times of the programing operation, the temperature of a column {1.5 % Silicone OV-17 on Chromosorb W (AW-DMCS), (6080) mesh, 1 m × 3 mm I. D., aged at 300 °C for 20 h} could be raised up to 300 °C without any significant base line drift under the pulse period (tP) below 200 μs. The peak heights of samples and the degree of the base line drift increased with increasing tP. It was thus important for programmed temperature operation using a constant-frequency ECD to select tP appropriately, depending on the temperature range programmed and the sensitivity required.
