the lifetime of a column operated with this method was estimated at
5000 injections.
3.5. Application of the deactivation method in other GC systems
In order to prove its versatility, the method was also applied in a Varian GC-430system. Since in this GC system the size of the injector is much smaller, the main adjustments concerned the amount of injected solutions. Deactivation was performed by injecting 0.5 L of IL in methanol 40 times with a split ratio of 50. The number of injections was kept at 40, since previous tests with Carlo Erba system proved that method was ineffective if lower amount of injections would be applied. The injection volume and split ratio
were adjusted experimentally. The amount of ethylene diamine was reduced in order to minimize the difference between its peak and the peak of putrescine or cadaverine. Samples for analysis (now containing only 167 L (10 wt%) ethylene-1,2-diamine) were
injected with 2.0 L volume, at a split ratio of 10. These valuesere adjusted experimentally, so that the detection of 1 mM of each diamine was possible. No changes in the temperature scheme were made. The column was operated at a constant flow mode with a helium pressure of 8 psi (55 kPa). Nitrogen was used as a make-up gas.
Excellent results were obtained for putrescine and cadaverine (see Fig. 3C). The number of injections per single deactivation procedure increased to 800, while the detection limit was maintained at 1 mM for both diamines. It was thus concluded that the method
is not system specific.