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- Posts: 1
- Joined: Mon Oct 10, 2005 10:38 am
Have some troubles with measuring metal chelates by GC.
Tested e.g. (fod*)3Pr; which has a sufficient volatility and is stable against air and moisture; it exist some positive literature, mostly with packed columns (e.g. SE30).
I Used:
4m HP-5ms,0.25mm,0.25µm, with retention gap 10m,0.32mm, column temperature programmed 60° to 240°C (max 240°C, otherwise more and more degradation at higher T is to be worried about), solvent benzene bp 80°C; 1µL(~1µg) splitless with solvent vent, quarz liner UNIS-Injektor, T-programmed from 70 to 220°C.
Results:
I got a peak at retention time ~ 5...6 min; peak width at half maximum ~ 11 sec; but with unacceptable tailing; limit of Detection (3s) ~0.1 pMol (MS-SIM with 731 amu, that is the (fod)2Pr-Kation). The peak appears exactly together-with the same profile-to that of 207 amu (but 207 amu is ~10 times in hight!); this column bleed peak shows to me, that the analyt degrades the phase; in deed, the REE-chelates (as other heavy metal chelates) are weak Lewis acids, despite their complexation.
Which other columns may I test, that promise more stability against Lewis acids?
I have in minde:
DB-1ms, DB-5ms (with bis(dimethylsiloxy) phenylene bridges), DB-XLB, DB-200/210, DB/HP-FFAP(WAX acid-modified), HP-INNOWax(hoch inert), DB-WAXetr, DB-1/5ht. What other stabil phase I could try, may be something with graphite e.g.?
*fod=[CF3-CF2-CF2-CO-CH-CO-C(CH3)3]-Anion, forms stable and volatile chelates with nearly all metals!
Tested e.g. (fod*)3Pr; which has a sufficient volatility and is stable against air and moisture; it exist some positive literature, mostly with packed columns (e.g. SE30).
I Used:
4m HP-5ms,0.25mm,0.25µm, with retention gap 10m,0.32mm, column temperature programmed 60° to 240°C (max 240°C, otherwise more and more degradation at higher T is to be worried about), solvent benzene bp 80°C; 1µL(~1µg) splitless with solvent vent, quarz liner UNIS-Injektor, T-programmed from 70 to 220°C.
Results:
I got a peak at retention time ~ 5...6 min; peak width at half maximum ~ 11 sec; but with unacceptable tailing; limit of Detection (3s) ~0.1 pMol (MS-SIM with 731 amu, that is the (fod)2Pr-Kation). The peak appears exactly together-with the same profile-to that of 207 amu (but 207 amu is ~10 times in hight!); this column bleed peak shows to me, that the analyt degrades the phase; in deed, the REE-chelates (as other heavy metal chelates) are weak Lewis acids, despite their complexation.
Which other columns may I test, that promise more stability against Lewis acids?
I have in minde:
DB-1ms, DB-5ms (with bis(dimethylsiloxy) phenylene bridges), DB-XLB, DB-200/210, DB/HP-FFAP(WAX acid-modified), HP-INNOWax(hoch inert), DB-WAXetr, DB-1/5ht. What other stabil phase I could try, may be something with graphite e.g.?
*fod=[CF3-CF2-CF2-CO-CH-CO-C(CH3)3]-Anion, forms stable and volatile chelates with nearly all metals!
