[nate]

Anyone know of a reference for the retention time of Methylene Chloride?

Doing a GC analysis and my reference standards do not match up to my sample.  I added some Methylene Chloride because my sample was so minimal.  Now I have no peaks that match my reference standards and the only peak I have is at 1.17 mins.  Any tips???

Thanks

[GSR]

hi,

you could get more information from analytical chemistry forum.

GSR

[movies]

Methylene chloride will have a very, very short retention time.  The exact retention time depends on the parameters of your GC and the particular run that you use.  Regardless of all that, a compound with such a low boiling point and low polarity will likely come off the GC with the injection front (typically less than 2 minutes).  For our GCs the typical dilution is about 1 mg of material in 1 mL of solvent.  When you do this, then you have a massive solvent peak at ~2 minutes, and then the rest of the stuff comes of considerably later.  To get meaningful GC traces you have to zoom in to the part after the solvent has come off and adjust the vertical scale to a reasonable size.  In a typical trace, the solvent peak with have a height around 30000 absorbance units and then the real peaks are more in the 100-200 AU range.

With our GC columns we aren't supposed to use chlorinated solvents because they degrade the column very rapidly, you might want to check this before you do more experiments with chlorinated solvents.  We usually dilute our samples in diethyl ether.