Chromatography Forum

I am considering installing an Agilent splitter (G3180B) to enable me to use an ECD in parallel with a MSD. Does anyone have any experience and advice/tips on using this accessory?

Thanks.

AP

ap01,

If you go onto one of the Agilent web sites, you can download the manual for this splitter. It will give you some idea of what it is and how it operates before you separate from your money.

Go to the following site:
www.chem.agilent.com/scripts/DownloadsUtilities.asp.

When you are on the web page, click on "Literature Library" which you will find on the left side of the screen. Then enter G3180B as the Keyword and do a search. You will be asked to login or register, and once you have done this you can download the manual. It is 3Mbytes in size.

Gasman

HI AP

The Agilent splitter is a quite sophisticated piece of hardware. Depending on how much money you have, and what kind of performance and versatility you need, you could also use a press-fit Y connector and two lengths of uncoated silica. The silica to the MS would have to be narrow bore to provide resistance against the vacuum in the MS source.

Peter

Ap,

The calculations for this can become a bit hairy with a lot of ifs and buts and depends when one of the splits is into the mass spec and will therefore be at a high temperature. As a rough guide I use 150cm of 0.10mm id or 220cm of 0.11mm tubing to get about 0.4ml going into the mass spec . The final calculation is

L1 = ((F x P1)/P2) x (R1/R2)^4 x L2

where F = the split ratio required
L1,P1,R1 are to the ECD and L2,P2,R2 are to the mass spec
I assume 15psi for the P2 and 0.1psi for P1.

Another option, which is easier to do, is to use a wide bore capillary for your analytical column. Insert the restrictor tubing to the MSD just inside the widebore column in a low dead volume t-piece splitter (from Agilent. Adjust the length of the restrictor to draw 2ml/min from the column and set the column flow to 5ml/min (which happens to give you optimum linear velocity) and the excess 3ml/min goes to your ECD. Effectively you have made an open split interface.

Regards,

Ralph

Coincidentally, I have an engineer in at the moment fitting a microfluidic G3180B to a 5975 so I won't be able to make many comments yet. I can say that when I ordered the GCMS with this in mind as a retrofit I had to order a specific version of it . I was given the impression that it would be easy both to alter the split ratios and to change back to conventional GCMS. From what I can see so far this won't be the case. At the end of the day it is the length of that restrictor into the MS which determines everything else. I may yet go back to the approaches that I outlined in the reply above.

Regards,

Ralph