Chromatography Forum

Hi all: I came accross this passage in a paper for silylation. How do I set the microwave up I don't quite understand what settings they used?

Sample derivatizations: The TMS derivatization (when not indicated otherwise) was based on the
optimized protocol described by Villas-Bôas et al. [6]. In summary, the dried samples were
resuspended in 80 L of methoxyamine hydrochloride solution in pyridine (2 g/100 mL) and incubated
in a domestic microwave oven for 2.8 min, with multimode irradiation set to 400 W and 30% of exit
power. MSTFA (80 L) was then added to each sample followed by 3.0 min incubation in a
microwave oven as described above.

I've used trimethylsilylation for 35 years. Typically, we shake 15 seconds in an autosampler vial at room temperature.

Occasionally we will heat 15 minutes on a steam bath.

Microwave ovens heat things - often there are better, cheaper, easier, safer ways of doing it. At the minimum you need to get the original reference [6] for details of settings, and what precautions they took against the crude power control of domestic microwave ovens turning the samples into toxic shrapnel.

Peter

I prefer the chloroformates because they react in aqueous conditions just fine but I have been trying like heck to be able to do Disodium inosinate (IMP) and Disodium Guanylate (GMP). SO far I've tried the chloroformates, phenylboronic acid for the ribose diol and then the chloroformate Pyridine+BSTFA+TMCS, Pyridine+MSTFA+TMCS, MSTFA+TMCS+ a few hours about 100 deg C and on column methylation with trimethylphenyl ammonium hydroxide. So far nothing has worked just empty chromatograms with traces of silyated impurities like glycerol or mid chain fatty acids.

I have Donald Knapp's book. It says Pyridine:BSTFA:TMCS 30:30:1 and either RT 30 min or 150degC. Several catelogs mention using Trimethylsilyl immidizaole which is strange as it only does hydroxyls and acids and won't do the amine on guanylate.

I am also concerned because to my knowledge nucleotides are not soluble in any organic solvents so after I evaporate it just sits there on the glass.