Conversion of nicotine to nornicotine is a challenge for tobacco leaf production. A gas chromatography-mass spectrometry-based method was developed for the rapid screening of seedling nicotine converters which would convert a large portion of nicotine to nornicotine as they grow up and mature. Two strategies (with and without incubation) were developed and evaluated. The non-incubation strategy including sampling, extraction, and instrument analysis takes up about 5-6 min for one seedling sample. With this strategy, the complete removal of converters was achieved with the sacrifice of 9 % non-converters. For the incubation strategy, in-tube samples were cured at 37 °C for 12 h before the extraction and the instrument analysis. Complete separation of converters and non-converters was achieved using the incubation strategy. A pseudo percent nicotine conversion (PPNC) was introduced for the replacement of the normally used percent nicotine conversion (PNC) as the converter Adjudicator. The PPNC proved to be simpler and more effective than the PNC. The established method is a good choice for the fast and efficient identification of nicotine converters from a big number of seedling populations.