Troubleshooting

Symptom: Missing peaks or solvent peak only
Possible Cause    Remedy
1. Impurities in solvent, starting material, catalysts, or extract may interfere with derivatization (e.g., plasticizers from vial, inorganics used in sample synthesis, preservatives or antioxidants in solvents).
2. Reagent deteriorated.
3. Reagent :sample ratio too low.
4. Rate of reaction too slow.
5. Water in reaction mix.
6. Wrong reagent.
7. Sample adsorbed to glassware.		   1. Use only highest purity materials at all steps in sample prepartion process.
2. Store reagent properly to prevent oxygen/water contamination, temperature damage (see product specification sheet).
3. Use more reagent for same amount of sample.
4. Reevaluate reagent concentration, time, temperature. Consider heating the reaction mix (consider thermal stability of the analytes and reagents). A catalyst will increase the reactivity of some reagents.
5. Remove water by adding sodium sulfate to sample. Store reagent properly to prevent oxygen/water contamination.
6. Reevaluate reagent selection.
7. Deactivate glassware, inlet sleeve, and column by silanization.
     
1. Reagent interacting with column.
2. Impurities from sample, solvent, reagents, sample vial, other labware.
3. Derivative undergoing hydrolysis.
4. Derivative reacting with solvent.		   1. Add more reagent, increase temperature or heating time, or add catalyst. Water may be present; add sodium sulfate to sample.
2. Clean FID per instrument manual.
3. 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 1-2 coils from inlet end of nonbonded column. If performance is not restored, replace column.
     
Symptom: Extra peak(s)
Possible Cause   Remedy
1. Reagent interacting with column.
2. Impurities from sample, solvent, reagents, sample vial, other labware.
3. Derivative undergoing hydrolysis.
4. Derivative reacting with solvent.		   1. Verify that reagent is compatible with analytical column.
2. Inject solvent and reagent blanks, solvent rinse from unused vial, etc. to isolate source of impurities.
3. Remove water by adding sodium sulfate to sample. Store reagent properly to prevent oxygen/water contamination.
4. Use a solvent that does not have an active hydrogen, alcohol, or enolizable ketone group (e.g., hexane, toluene, etc.).
     
Symptom: Detector response low
Possible Cause   Remedy
1. Low yield of derivative - reaction did not go to completion.
2. Detector (FID) dirty.
3. Sample components absorbed by inlet liner or column.		   1. Add more reagent, increase temperature or heating time, or add catalyst. Water may be present; add sodium sulfate to sample.
2. Clean FID per instrument manual.
3. 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 1-2 coils from inlet end of nonbonded column. If performance is not restored, replace column.
     
Symptom: No sample separation after adding reagent and heating
Possible Cause   Remedy
1. Septum in reaction vial not sealed.   1. Prepare a new sample and derivatize. Be sure vial is sealed.
     
Symptom: Low Yield
Possible Cause   Remedy
1. Improper handling technique : extra steps allow more room for error (e.g., low boiling components could be lost during sample concentration); sample too dilute; wrong solvent.
2. 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).
3. Reagent deteriorated.
4. Reagent :sample ratio too low.
5. Rate of reaction too slow.
6. Water in reaction mix.
7. Wrong reagent.
8. Sample adsorbed to glassware.
9. Carrier, air, detector (FID) hydrogen, or make-up gas flow set incorrectly.		   1. Reevaluate technique, if possible eliminate steps in which analyte could be adsorbed or otherwise lost (unnecessary transfers, etc.).
2. Use only highest purity materials at all steps in the sample preparation process.
3. Store reagent properly to prevent oxygen/water contamination, temperature damage (see product specification sheet).
4. Use more reagent for same amount of sample.
5. Reevaluate reagent concentration, time, temperature. Consider heating the reaction mix (consider thermal stability of the analytes and reagents). A catalyst will increase the reactivity of some reagents.
6. Remove water by adding sodium sulfate to sample. Store reagent properly to prevent oxygen/water contamination.
7. Reevaluate reagent selection.
8. Deactivate glassware, inlet sleeve, and column by silanizing.
9. Measure flows and set according to instrument manufacturer’s recommendations.