Thermo Scientific
| Reagents, Solvents and Accessories
9
MSTFA and MSTFA + 1% TMCS
Offers maximum volatility.
20
MSTFA
MW 199.1
bp 70
˚
C/75 mm
d
4
1.11
C
CF
3
N
Si
CH
3
CH
3
CH
3
O
CH
3
Highlights:
• Trimethylsilyl donor strength comparable to BSA and
BSTFA
• Reacts to replace labile hydrogens on a wide range of
polar compounds with a -Si(CH
3
)
3
group
• Used to prepare volatile and thermally stable derivatives
for GC and GC/MS
• Primary advantage of Thermo Scientific MSTFA is the
volatility of its byproduct, N-methyltrifluoroacetamide;
MSTFA is the most volatile TMS-amide available which
has an even lower retention time than MSTFA
• Often TMS derivatives of small molecules can be analyzed
when derivatized with MSTFA because the byproducts
and reagent itself usually elute with the solvent front
• Addition of Thermo Scientific TMCS aids derivatization
of amides, secondary amines and hindered hydroxyls not
derivatized by MSTFA alone
MSTFA is the most volatile TMS-amide available – its
even more volatile than BSTFA or BSA. Its byproduct,
N-methyltrifluoro-acetamide, has a lower retention time in
GC applications than MSTFA itself. This makes it ideal for
GC determinations in which the reagent or byproducts may
obscure the derivative on the chromatogram. Silylation of
steroids shows MSTFA to be significantly stronger in donor
strength than BSTFA or BSA. MSTFA will silylate
hydrochloride salts of amines directly.
PROTOCOL
1. Combine 5-10 mg sample, 0.5 ml MSTFA and 1.0 ml solvent (acetonitrile is
recommended for amino acids) in a 3.0 ml Thermo Scientific Reacti-Vial
Small Reaction Vial.
2. Cap vial and shake for 30 seconds.
3. Heat at 70°C for 15 minutes.
4. Analyze by gas chromatography.
Ordering Information
Product # Description
Pkg. Size
TS-48910
MSTFA
10 x 1 ml
(
N
-Methyl-
ampules
N
-trimethylsilyltrifluoroacetamide)
TS-48911
MSTFA
10 g
Hypo-Vial Sample
Storage Vial
TS-48913
MSTFA
25 ml
Hypo-Vial Sample
Storage Vial
✖
TS-48914
MSTFA
100 ml
Hypo-Vial Sample
Storage Vial
TS-48915
MSTFA + 1% TMCS
10 x 1 ml
(
N
-Methyl-
ampules
N
-trimethylsilyltrifluoroacetamide+
1% Trimethylchlorosilane)
✖
Additional hazardous handling charge.
BSA
The perfect reagent for volatile TMS derivatives.
20
BSA
MW 203.4
bp 71-73
˚
C/35 mm
d
4
0.832
C
CH
3
N
Si
CH
3
O
Si
CH
3
CH
3
CH
3
CH
3
CH
3
Under relatively mild conditions, Thermo Scientific BSA
reacts quantitatively with a wide variety of compounds to
form volatile, stable TMS derivatives for GC analysis. BSA is
used extensively for derivatizing alcohols, amines, carboxylic
acids, phenols, steroids, biogenic amines and alkaloids. It is
not recommended for use with carbohydrates or very low
molecular weight compounds.
BSA is used in conjunction with a solvent such as pyridine
or DMF, and reactions are generally rapid. When used
with DMF, BSA is the most suitable reagent for derivatizing
phenols. A study of the silylating properties of BSA made by
Klebe, Finkbeiner and White showed the following reactions
with BSA:
• Amino acids to form both
N,O
-bonded TMS derivatives
• Hydroxyl compounds to form TMS ethers
• Organic acids to form TMS esters
• Aromatic amides to form N-TMS derivatives
PROTOCOL 1
1. Combine 5-10 mg sample, 0.5 ml BSA and 1.0 ml solvent (acetonitrile is
recommended for amino acids) in a 3.0 ml Thermo Scientific Reacti-Vial
Small Reaction Vial.
2. Cap vial and shake for 30 seconds.
3. Heat at 70°C for 15 minutes.
4. Analyze by gas chromatography.
PROTOCOL 2
This method was developed by E.M. Chambaz and E.C. Horning for the
silylation of hydroxyl groups in sterically unhindered positions in
steroids. This includes sites such as 3, 7, 16, 17(sec), 20 and 21
positions in the steroid structure. This method may be used for
silylating many hydroxyl and poly-hydroxyl compounds other than
steroids. It is not recommended, however, for sugars. The method is
based upon the use of BSA in an uncatalyzed reaction. No trimethyl-
chlorosilane should be used in this reaction. Hydrochlorides should be
avoided because HCI also will act as a catalyst.
1. Combine 0.1-5.0 mg of sample and 0.2-0.4 ml BSA in a 1.0 ml Thermo
Scientific Reacti-ViaI Small Reaction Vial. If material is not soluble in BSA,
add 0.1-0.2 ml pyridine.
2. Cap vial and shake for 30 seconds.
3. Heat at 60°C to ease dissolution, if desired.
NOTE:
Material is silylated at room temperature within times varying
from a few minutes to a few hours. Heating will hasten reaction.
Ordering Information
Product # Description
Pkg. Size
TS-38836
BSA [
N,O
-bis(trimethylsilyl)acetamide]
10 x 1 ml ampules
TS-38838
BSA
25 g Hypo-Vial Sample
Storage Vial
✖
TS-38839
BSA
100gHypo-VialSample
Storage Vial
✖
Additional hazardous handling charge.
