AbstractSubnanogram detection of steroids has become increasingly important today. One applicable method for gas chromatographic determination of subnanogram quantities of estrogens as halogenated derivatives is electron capture detection. HFB‐derivatives of 7 different estrogens were automatically injected onto a prolonged narrow bore wall‐coated glass capillary column. Normal split injection could not be used for this trace analysis because of too much loss of sample. Only small amounts of sample were available from which double analysis had to be performed.Cross‐contamination of the automatic sampling system as well as precision of retention times and peak areas were determined.The type of injection described showed better quantitative results compared to the splitless injection technique.All details of the system used together with the results are this discussed in this paper.