ethanol Assay use water as solvent : precision problem

[kka626]

Sorry, I mean auto-injector generate peaks shoulder/tailing problem. Inject manually , STD n Internal STD come out nicely.

[kka626]

Want ti update my study. Back to Using auto-injector but no wool in the liner. Peaks look nice, but bad precision. Peak height jump up n down. Not like before with wool.

[twranger]

Check your injector temp and liner volume. We're using a 4mm liner with glass wool (need to vaporize water) and 220C injector. Also consider a larger bore column, or at least a retention gap of 0.53mm column for the water vapor. Our peaks tail a bit, but they are repeatable up to 500ppm.

[iiYama]

You should pay special attention at sample injection quality.

If you use sampler try to reduce plunger injection speed. Also wool position may be important - do you fill this liners with wool by your own? If yes try to increase its amount and create it bit closer to liner edge. Injecting the sample inside the wool may help.

If you compare AOC and manual syringes what about needle length? Manual syringes I used for Shimadzu GC's had longer needles so injection was made bit deeper in comparision to sampler syringes.

I your peak tend to tailing it might be because of column. Try to conditioned them.

Shimadzu offers special FID jet for water analysis. Did you try it?


Good Luck!

[Bigbear]

I know it seems counter intutative but when injecting water the injection port should not be more than 100. Due to the large expansion of water you should not inject more than 0.5 ul.