Hi to all,

our lab´s currently solving problem with new methods. Our client wants to determine Ethylene oxide, Propylen oxide and 1,4-dioxan" in Poloxamers matrix. The required method is according to European Pharmacopoeia (no changes).

The method according to Ph.Eur:
- capillary column, 50m x 0,32mm, 5 µm film, fused silica with Phenyl(5)methyl(95)polysiloxane R as a stacionary phase. We use Agilent CP-Sil 8 CB after consultation with Agilent.

Headspace conditions:
- equilibrium for 30 min at 110 °C
- transfer line temp 140 °C
- press. time 1 min, inj. time 0,05 min

- splitless injection
- septum purge flow 3 ml/min
- flow rate 1.4 ml/min
- carrier gas helium

Oven program:
0 - 10 min 70 °C
10 - 27 min 70 - 240 °C
Inlet and FID temp - 250 °C both

Our GC system:
Agilent GC 7890B - model G3440B
Headspace 7697A - model 64557A

And we use Empower Enterprise by Waters as software.

The samples and reference solutions are prepared into dimethylsulfoxide as a solvent.

And what is my problem…. If I measured this method, the peaks are splitted and really small. After I decreased equilibrium and transferline temps to 100 and 130 °C, the peaks have good shape, no splitting. But they are still small.
The S/N ratio for ethylene oxide is about 4, if I prepare only solution of the analytes in DMSO, no Poloxamers addition.

If I prepare reference solution as is, there are no peaks at all.

Any idea how to increase the response? Method change or anything. The column is new and installation is right (controlled several times), inlet and FID cleaned.

Thank you for all ideas of yours!
Martini