GC analysis of tethyl borate

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PRAVEEN PALIWAL
PRAVEEN PALIWAL's picture
GC analysis of tethyl borate

Sir,

I am going to analyze Trimethyl borate on GC, Initially I have used TC-1 and get RT about 5 minutes but after some time RT was reduced to 3 minutes and peak tailing was observed.
I have doubt on column and I analyze it on DB-XLB column I got good peak shape and RT near 3.5 minutes. After some time again RT shift up ward i.e 1.9 minutes and peak tailing was observed.
I donot understand what is the resion.
My column condition is 60 degree (hold 2min.)@ 10 degree up to 200degree(3min. hold)
Injetor is 200 degree and detector was 259 degree.
carrier is N2 with 10: 1 split and 10 psi flow rate/.
As I understand TMB is harmful for both column or we should try another column for the analysis.

please suggest

Praveen

Dr. Analytical
Dr. Analytical's picture
What is your injection

What is your injection solvent?  What kind of liner are you using, and does it include a packing?

How many injections before the retention time and peak shape change?

The increase in tailing could be caused by problems in the injector/liner.  Is anything else dissolved in the solution?  If a non-volatile component is injected it will remain in the liner, and may cause problems with the next injections.

The changing retention times may mean that your column is being degraded.  Depending on your column length, you should be able to remove the firont of the column (10 - 20 cm) and analyze again.  if the shape and retention time improve, then you have a problem with something either contaminating the column or coating it.

This is a very reactive compound, so you may have difficulty finding a good column.  Have you found any other references to this application.

PRAVEEN PALIWAL
PRAVEEN PALIWAL's picture
Sir,

Sir,

I inject trimethyl borate as such just 0.2michroliter neat. I have glass liner and the peak shape is changed about 20 -25 injection. As per I result found I have also doubt that this is very reactive compound.
My conseris not to analyze this compound on GC but also found the methanol peak which is also formed when this material is slight exposed in air or enviorment.
I donot have any literature about this material analysis.

But I can try to dilute this materila is another solvent may be it will less harmful for my column

Dr. Analytical
Dr. Analytical's picture
You are injecting too much on

You are injecting too much on your column.  It is also possible that this compound is unstable at high temperatures, and it may be decomposing in your liner or inside the column. 

Dissolve it in a solvent such as hexane or dichloromethane, at a concentration of 1 mg/mL and evaluate the chromatography.  More dilute solutions may also be better.

PRAVEEN PALIWAL
PRAVEEN PALIWAL's picture
Ok,

Ok,

Sir, I will diluted the sample in hexane and inject on column. Can u suggest me that the column with 100% dimethyl polysiloxane is suitable for the analysis of I have to change the column also??

Besta regards

Praveen

Dr. Analytical
Dr. Analytical's picture
You can try this column and

You can try this column and evaluate.  A more polar column may be required (e.g., 5 % phenyl) but it is difficult to predict which column is best.