| 1 |
Acylation |
|
α-Methoxy-α-trifluoromethylphenylacetic acid (MTPA) |
|
(i) It is acidic and called Mosher's acid |
| (ii) Very effective in generating ions of analytes |
| Acetic anhydride |
|
(i) Improves selectivity in GC, MS, and FID detectors, especially negative chemical ionization |
| (ii) Generally used by base compounds such as biogenic amines |
| 4-Carbethoxyhexafluorobutyryl chloride |
|
(i) Very stable for secondary amines because it can remove the excess agent by adding protic solvents |
| Heptafluorobutyrylimidizole (HFBI) |
|
(i) Fast reaction and suitable for amine and alcohol |
| (ii) Byproduct is not acidic |
|
N-Methyl-N-bis (trifluoroacetamide) (MBFTA) |
|
(i) Acceptable and fast for primary and secondary amines |
| (ii) Byproduct is volatile |
| N-(Trifluoroacetyl)-prolyl chloride (TPC) |
|
(i) Generally applied for amine compounds |
| (ii) With a proton at the chiral center in the α position to the carbonyl group in order to avoid racemization through keto-enol tautomerization and thus reaction and storage conditions must be controlled |
| Pentafluorobenzoyl chloride (PFBCI) |
|
(i) Very reactive, obtaining the most sensitive ECD derivatives of amine |
| Propyl chloroformate |
|
(i) Derivative analyte is water soluble; thus, the byproducts can be removed using water |
|
| 2 |
Alkylation |
| BF3/methanol (n-butanol) |
|
(i) Obtaining methyl (butyl) ester with acid |
| (ii) Fast and quantitative esterification/transesterification |
| (iii) No side reactions with volatile byproducts |
| Tetrabutylammonium hydroxide (TBH) |
|
(i) Very reactive to low molecular weight amines |
| Trimethylanilinium hydroxide (TMAH) |
|
(i) Knows as a flash alkylation reagent |
| (ii) Quantitative derivatization of nitrogen-bearing molecules |
|
| 3 |
Silylation |
| Hexamethyldisilazane (HMDS) |
|
(i) A weak (trimethylsilyl) TMS donor |
| (ii) It applies without solvent, yet the reagent capacity can be increased by the acidic catalyst |
| (iii) Byproduct can leave the reaction mixture as the reaction goes to completion |
|
N, O-Bis (trimethylsilyl) acetamide (BSA) |
|
(i) Product derivatives are stable |
| (ii) Byproduct elutes with the analyte |
| (iii) Reactions are fast and quantitative |
| (iv) BSA and its byproducts are more volatile than other silylating reagents causing less chromatographic interference |
|
N, O-Bis (trimethylsilyl) trifluoroacetamide (BSTFA) |
|
(i) Faster than BSA and more complete |
| (ii) Reacts with a range of polar organic compounds by replacing active hydrogens with a TMS group |
| (iii) TMCS addition is recommended in order to control hydroxyl presence and other functionalities |
| (iv) Reduces the sensitivity of FID detector |
|
N-Methyl-N-(t-butyldimethylsilyl) trifluoroacetamide |
|
(i) Very reactive and stable |
| (ii) To hinder alcohol and amine groups and add a catalyst such as t-butyldimethylchlorosilane |
| (iii) Does not release HCl |
| (iv) Very suitable for mass spectrometry detector as it provides high-mass ions |
| Trimethylchlorosilane (TMCS) |
|
(i) A catalyst and forms HCl as a byproduct |
| (ii) Completes the derivatization step after secondary amines derivatized by BSTFA by adding 1–20% TMCS to BSTFA |
| Trimethylsilyldiethylamine (TMS-DEA) |
|
(i) Suitable for amino and carboxylic acids |
|
N-Trimethylsilylimidazole (TMSI) |
|
(i) Reacts with -OH and cannot react with aliphatic amines |
| (ii) It is stable thermally yet more susceptible to hydrolysis |
