Connect carrier gas, hydrogenandair to the
GC. Helium is recommendedas carrier gas,
while thehydrogenandair are required for
theFID ( flame ionizationdetector )which is
used todetect the samplemolecules.
Note: Some pre-made calibration standards ( Su-
pelco 44918-U ) are 10 times less concentrated,
but the instructions specify adding 10 timesmore
volume resulting in the samemass injected.
Prepare your calibration standards. Youwill
needglycerin ( 500ppm ), butanetriol
( 1000ppm ),monoolien ( 10000ppm ), tricaprin
( 8000ppm ), diolien ( 5000ppm ) and triolien
( 5000ppm ) eachdissolved inpyridine. You can
buy these startingmaterials( stock solutions )
fromSupelco( part#44898-U ), Restek, or other
sources. Youwill alsoneedaderivitization re-
agent calledMSTFAandHeptane ( a common
solvent ).
TheASTM6584method specifies that for the
highest calibration level ( level 5 ), 100ul of each
material ( inpyridine ) isadded toa10ml vial
alongwith100ul ofMSTFA. Allow20minutes for
the reaction tooccur, thenadd heptane tobring
the final volume to8ml.
TheASTM6584methoddescribesmaking the
calibration standardsat 5different levels, so the
level 1 calibration standard ispreparedusing
10ul of each startingmaterial insteadof 100ul,
but theprocedure isotherwise the same.
PerformingASTM 6584 free and total glycerin in
BioDiesel using anSRI GasChromatograph
andPeakSimple software
You can also use the optional SRI H2-40hydrogen
generator and “whisper quiet” built-in air compressor
to provide all necessary gases without bulky gas cyl-
inders
A 100ul syringe is helpful for making the dilutions
along with vials, and pipets.
Youwill need the startingmaterials plusMSTFA and
Heptane. Some pyridine is also handy to
have on hand.
