Chromatography Forum

Dear all,

I asked local supplier to give me the prices for DB-5 MS type column what I would like to buy. Apart DB-5 ms and BPX-5, they mentioned VB-5 MS column which would cost me ½ price of DB-5. As I understood they try to promote new product on the market, therefore the price is low.

Has anyone used this column ? It comes from Vici company, which is not actually so well known here in Europe.
Any kinds of comments are wellcome. Thanx.

Dear Olga,
If they are really keen to sell then they will let you try one. If it works they can invoice you.
If not you can send it back.
I have not heard of them personally.

Be very aware of RT and resolution/selectivity differences between apparently similar phases.
Be aware of differences between e.g. a "5" and a "5MS".
Maybe you know this anyway?

Hello WK, thank you for replying

I guess your are right, that the best way to find it out is just to try it..

Dear Olga,

Be very aware of RT and resolution/selectivity differences between apparently similar phases.
Be aware of differences between e.g. a "5" and a "5MS".
Maybe you know this anyway?

Well, I don't so much between "5" and "5MS"... I am buying it for GC-MS. In old days all columns were just "5" and we used them for both FID and MS. Now they say that "5MS" is more suitable for MS, but why, actually I don't know...
However, the point is that I have DB-5 60m and DB-5 30 m columns running in 2 GC-FID's. Therefore, I would like to have the same polarity column in GC-MS which now contains OV-1701 !!
What do you think it would be the best choice then to have for GC-MS?
Do you DB-5 would match better than DB-5MS for GC-MS in this case?

Olga,

The DB-5MS columns are just supposed to be lower bleed versions of the DB-5 phase materail, same polarity and selectivity. I have used both and seen no differences (other than a little better bleed). They are interchangable. Actually, unless you are doing high temp work or analyzing very low level samples the usual DB-5 phases work just as well on the GC-MS.

Regards,
Mark

A ms column is supposed to have the lowest bleed,or lower as a normal column.
In most case a column is named ms if it has low bleed but is totally identical to a normal

In other case the chemistry of the column phase is different enough to provide a lower bleed that is the reason why db5 and db5-ms are not 100% the same.

DB5 is 5% Phenyl-methylpolysiloxane phase
DB5-ms is Phenyl-Arylen-Polymer equivalent to a DB5,although that's a little difference,this could affect selectivity...elution order

Mark, xxx - THANK you !

I know Varian sells a new family of GC columns, the VF-serie. With this type of columns the bleed is a factor four lower than its equivalents. This is only important if your temperature programming is higher than 200 °C. Besides the bleeding the life span is a factor 2 higher.

Durk