Split baseline and streaks

[maricreese]

I have for some time had split column bleed and also streaks occuring in the 2D space. I've tried eliminating dead volume by using µ-unions and 0.25 mm ID modulation loop (ZX2 modulator). Any suggestions how to overcome this?

Hexane_new-unions_7s.jpg (58.45 KiB) Viewed 1833 times

[infomassllc]

You also have "double peaks" for the components around 17 min 1st dimension retention time. The possible reason could be that the time components traveled inside the modulation loop was shorter than the hot jet duration time. I will need more detailed GC conditions and column configuration to figure out the exact reason.

[maricreese]

The column set is as follows: HP5 (30 m x 0.25 mm, 250 µm) x BPX50 (1.2 x 0.25, 250 µm) connected with a 1 m, 0.25 mm loop. Modulation period 7000 ms and hot jet duration 350 ms.
GC oven temperature 60 oC start with 4 oC/min ramp to 310 oC. Hot jet is constant +50 oC offset (110 - 360 oC).

The loop positioning has been double checked and is perfectly aligned with both the cold and hot jet streams.



Thanks in advance for advice.