Chromatography Forum

Good day - new user here.

I recently implemented a good procedure for ethylene glycol quantitation out of biologicals. The method uses phenylboronic acid as the derivative, and analysis of 20uL of acetone containing the analyte via a headspace analysis (Gerstel gastight syringe + Agilent GC/MS).

Works great, super simple, very accurate - just one problem. After analysis we get a lot of ghost peaks on blank chromatograms, and c'graphy seems somewhat degraded in general. Often the column is replaced.

Does anyone have a suggestion about restoring the instrument performance short of column replacement?

edit: more specific method points: 100uL of sample, plus 400uL of 5ug/mL PBA in acetone. Vortex. Remove 20uL of acetone to a 10mL headspace vial and cap. Equilibrate on the Gerstel, and inject 100uL (1000uL syringe) on column (DB-5/equivalent). Temperature ramp on GC/MS, max 280 held for 5 minutes (Gerstel is flushed out at maximum available temp and time). Instrument is switched back to liquid injection mode when the glycols are done for the quarter, and that's when we really notice the degradation in performance.

Boron has isotopes and you have a Gc/MS system......can you ID the ghosts ? At least as to type of compound ...

Regards,
JMB

I use phenylboronic acid to quantitate 3-monocloropropane diol or 3-mcpd. It is recommended to keep the inlet at 180 deg C and use a liner with wool on the bottom.

My simple protocol is
-sample to 5ml with water/ITSD
-1ml PBA solution in acetone
-90degC 30 min
-Cool and add 2ml hexane and a small spoon of NaCl ~1-2g.
-Inject hexane layer.
-Take GC column to 325 to elute triphenylboroxin blob peak.

Just in case the OP is still watching. I clean my system after running PBA derivatives by injecting 2 blanks of a high concentration propylene glycol acetone solution (ethyl acetate is probably better as the two can react). The propylene glycol reacts with the residual PBA in the GC and the derivative is much more volatile and gets swept out.