Rapid measurement of free phytosterols in tobacco by short-column GC/MS/MS

Phytosterols occur in plants, including tobacco, in free and bound forms. A GC/MS/MS method to quantify free phytosterols in plant materials was investigated. Free phytosterols in tobacco were extracted and directly analyzed without any preinjection sample treatments. A short GC column was used to reduce the retention of sterols in the severe GC conditions, and the chances of dehydration or decomposition were reduced. A highly selective tandem mass spectrometric detection called multiple selected reaction monitoring not only eliminated all of the chemical background of the crude tobacco extract but also compensated for the loss of GC resolution due to the short column. In a single GC injection, sterols that had not been resolved by GC were detected individually with the multiple selected reaction monitoring scan. This direct GC/MS/MS method provides reliable and reproducible quantitative results for free phytosterols in tobacco.