Improvement of simulated distillation methods by gas chromatography in routine analysis

Simulated distillation (SD) by gas chromatography (GC) is a technique which advantageously! replaces traditional distillation methods for rapid checki ng of petroleum products yields. If the principle is simple (separation of the components according to their boiling point by the GC column) the imple mentation is less obvious. The first problem concerns the choice of the the stationary phase to obtain good agreement with the real distillation curve s; the second is the stability of this phase at the maximum temperatures us ed. There are many interdependent parameters involved in these two problems . Although several methods have been standardized their applications give r ise to a number of difficulties in routine use: need to choose operating co nditions (standard methods indicate only some possibilities), determination of the procedure (calibration, blank, quantification, etc.) compatible wit h automation and reproducibility of the method, data processing to assure a goon result.