Excessive MS Bleed using Trinity P1 Column

[indium]

I am using an Acclaim Trinity P1 column with a mobile phase of 10mM AmFm in 0.2% HCOOH (pH 3.1) and acetontrile. Column temp: 30C. I am running at 0.3 mL into a TOF. There is a huge (15 million counts!!!) ion at m/z 347.27 (sat'd signal of course) at 10% ACN which goes down by about one half at 90% ACN so still huge. The ion goes away when the column is removed and replaced with a union. According to the Dionex/thermo web site the column has an operating pH range of 2.5 to 7 with a recommended operating pH of 3.0-6.2, so I should ok there. The column is new and never been used before, and I also have a used one that also gives the same ion. I have had the column conditioning for severla hours but not much change. This column is supposed to be MS compatible.

Does anybody have any ideas what is going on. Is this normal. For those Dionex folks out there the serial is 001003, Lot 006-04-069, product# 075564. It appears to have been Qc'd on 07-Apr-2011.

Thanks.

[indium]

I contacted Dionex support and the response I received is shown below. They acknowledge the presence of this column bleed, but I am astounded they would consider this acceptable for MS analyses, and they fail to recognize that an intense continuous column bleed could suppress the ionization of many analytes. While I am sure there are a few cases where the bleed may not have much effect I would not class this column for general MS usage. I am dispointed that this column is considered MS compatible. Also, it is surprising to me that many (maybe all) the manufacturers of these specialty "MS compatible" columns do not provide MS spectra using typical MS eluents (maybe now I know why), and some even use TFA in their mobile phase to QC their columns which requires extensive column conditioning if you want to work in negative ion mode.

We have gotten some more feedback on this issue from product management and applications specialists who have used this column.
Their comments follow:

“The column is compatible with MS and CAD, which has been confirmed by many internal and external customers.

Like any other columns, this column does have some bleed-related background in MS. It should be noted that the apparent background is higher than a C18 column, partly because the nitrogen-containing bleeding is much more sensitive in MS than the bleeding from a C18. But it should not interfere with the analysis as reported here. The observed issue can be mitigated by applying column wash (detailed in column manual Section 4.7.2 http://www.dionex.com/en-us/webdocs/756 ... -Jan11.pdf).”

“As mentioned, the highly intense peak observed in MS is normal.

Depend on the types of MS, the intense peak from column bleed may or may not affect the results. Unless customer is using ion trap (other trap based instruments) or the targeted compounds has a m/z MS can’t resolve from the column bleed peak, this strong peak should not affect the results.

In this case, a TOF MS is used, and I assume it is operated in full scan mode then extract the compound of interest. This column bleed MS peak can be “removed” from full scan spectrum using background subtraction.”

We see that apparently some bleed is normal for this column. They do not seem to identify this specific mass material, but suggest it is fairly specific and unlikely to interfere. Hope this provides some additional explanation, guidance and advice for proper washing to help alleviate the issue.

For further assistance, contact the Customer Support (see below). The Dionex Reference Libraray CD (PN 053891) and Dionex website (http://www.thermofisher.com/dionex) are excellent sources for MSDS's, manuals, applications, systems, modules and training.

Thank you for the opportunity to assist you.