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Alkylation reagents for GC
| In GC generally methylation is the main type of alkylation used. |
| Methylation reagents |
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N,N-dimethylformamide dimethylacetal
M 119.17 g/mol · Bp 106–107 °C (760 mm Hg),
density d20°/4° = 0.897 |
DMF-DMA |
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Methylation with DMF-DMA can be applied for fatty acids, primary amines and (partially) amino acids forming N-dimethyl-aminomethylene amino acid methyl esters. DMF-DMA is a poor solvent, for this reason it is necessary to use a mixture of DMF-DMA with pyridine, THF, acetone (barbiturates) or another solvent.
For a working protocol click here. |
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Trimethylsulfonium hydroxide (0.2 M in methanol)
M 94.06 g/mol |
TMSH |
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Methylation with TMSH is recommended for free acids, chlorophenoxycarboxylic acids, their salts and derivatives as well as for phenols and chlorophenols. One great advantage is simplification of the sample preparation. Lipids or triglycerides can be converted to the corresponding fatty acid methyl esters (FAMEs) by a simple transesterification.
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This reaction is very elegant and convenient, because it is just necessary to add the reagent (0.2 M in methanol) to the sample solution. Removal of excess reagent is not required, since in the injector of the gas chromatograph at 250 °C pyrolysis to volatile methanol and dimethylsulfide will occur. Due to the high reactivity, complete derivatization is often obtained at ambient temperature. However, heating (e.g., 10 min at 100 °C) in a closed sample vial may be necessary.
For a working protocol click here.
For GC separation of FAMEs from natural butter fat after derivatization with TMSH see
application 201680. |
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Methylation with methanol/TMCS
A 1molar solution of TMCS in methanol is suited for the esterification of free carboxylic acids and transesterification of glycerides. Formation of HCl catalyzes the reaction. TMCS and silyl ether remove water and thus drive the reaction to completion. The mixture should be prepared fresh.
For a working protocol click here. |
Ordering information
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Packing unit |
| Substance |
10 x 1 mL |
20 x 1 mL |
1 x 10 mL |
5 x 10 mL |
| DMF-DMA |
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701430.201 |
701430.110 |
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| TMSH |
701520.101 |
701520.201 |
701520.110 |
701520.510 |
| Due to their purpose, derivatization reagents are very reactive substances. For this reason they should be stored cool and protected from moisture. Our derivatization reagents are supplied in vials with crimp caps for easy access with a syringe. Vials with pierced sealing disks have limited stability and should be used soon. |
| These products contain harmful substances which must be specially labeled as hazardous. For detailed information please see MSDS. |
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