Thermo Scientific
| Reagents, Solvents and Accessories
5
Derivatization Problem Possible Cause
Recommended Solution
Low Yield
Carrier, air, detector (FID) hydrogen or make-up gas flow set
incorrectly
Measure flows using a Thermo Scientific GFM Pro Gas Flow
Meter and set accordingly using instrument manufacturer’s
recommendations
Reagent deteriorated
Store reagent properly to prevent oxygen/water contamination,
temperature damage (refer to product specification sheet)
Rate of reaction too slow
Re-evaluate reagent concentration, time, temperature and consider
heating the reaction mix (consider the thermal stability of the
analytes and reagents)
Water in reaction mix
Remove water by adding sodium sulfate to sample. Store reagent
properly to prevent oxygen/water contamination
Improper handling technique: (e.g. Low boiling components could
be lost during sample concentration); sample too dilute; wrong
solvent
Re-evaluate technique, if possible eliminate steps in which analyte
could be adsorbed or otherwise lost (unnecessary transfers etc.)
Wrong reagent
Re-evaluate reagent selection and select more appropriate reagent
Impurities in solvent, starting material, catalysts, or extract
interfering with derivatization (e.g. Plasticizers from vial,
inorganics used in sample synthesis, preservatives or
antioxidants in solvents)
Use only highest purity material at all steps in the sample
preparation process
Reagent: sample ratio too low
Use more reagent for same amount of sample
Sample adsorbed to glassware
Deactivate glassware, inlet sleeve and column by silanizing
No sample separation
after adding reagent and
heating
Septum in reaction vial not sealed
Prepare a new sample and derivatize. Be sure that the vial is
sealed
Detector response low
Sample components absorbed by inlet liner or column
Inject standard on column known to be performing well. If results
are good, remove inlet liner and check cleanliness. Use new,
deactivated liner or replace glass wool and packing. Rinse bonded
phase column or remove a few cm from inlet end of non-bonded
column. If performance is not restored, replace column
Low yield of derivative - reaction did not go to completion
Add more reagent, increase temperature or heating time or add
catalyst. Water may be present; add sodium sulfate to sample
Detector (FID) dirty
Clean FID as per instrument manual
Extra peak(s)
Derivative reacting with solvent
Use a solvent that does not have an active hydrogen, alcohol or
enolizable ketone group (e.g. Hexane, toluene etc. )
Impurities from sample, solvent, reagents, sample vial, other
labware
Inject solvent and reagent blanks, solvent rinse from unused vial
etc. Isolate source of impurities
Reagents interacting with column
Verify that reagent is compatible with analytical column
Derivative undergoing hydrolysis
Remove water by adding sodium sulfate to sample. Store reagent
properly to prevent oxygen/water contamination
Missing peaks or
solvent peak only
Wrong reagent
Re-evaluate reagent selection
Reagent deteriorated
Store reagent properly to prevent oxygen/water contamination,
temperature damage (refer to product specification sheet for stor-
age conditions and reagent lifetime)
Rate of reaction too slow
Re-evaluate reagent concentration, time, temperature and consider
heating the reaction mix (consider the thermal stability of the
analytes and reagents)
Impurities in solvent, starting material, catalysts, or extract
interfering with derivatization (e.g. Plasticizers from vial,
inorganics used in sample synthesis, preservatives or
antioxidants in solvents)
Use only highest purity material at all steps in the sample
preparation process
Sample adsorbed to glassware
Deactivate glassware, inlet sleeve and column by silanizing
Reagent: sample ratio too low
Use more reagent for same amount of sample
Water in reaction mix
Remove water by adding sodium sulfate to sample. Store reagent
properly to prevent oxygen/water contamination
Troubleshooting
