By Hyun Joo on Monday, June 7, 2004 - 07:05 am:

When I run samples, even blank, with LC/MS, I always have huge background noise in Total Ion Chromatogram (TIC). It seems that there are lots of contaminants in mobile phase. So I tried to use mobile phases without filtering of HPLC solvents. Suddenly,the noise in TIC has almost disappeared. I think the problem is not the solvent grade but the solvent contamination during the filtering. I have some information that Burdick & Jackson sells never filter B&J solvents. If this is true, what kind of solvent type from B&J can I try? Or any better ideas? Does anyone have answer for this? If so, I really appreciate it. Thank you.

Hyun

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By MG on Monday, June 7, 2004 - 07:14 am:

We use HPLC grade B&J solvents with LC/MS, and we do not filter for the reason you have just experienced.

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By Hyun Joo on Monday, June 7, 2004 - 08:32 am:

Thanks MG for your quick response. By the way, can I use any kind of HPLC grade B&J solvents? I have seen several types in the catalog. Could you recommend one or model number,etc? Thank you.
Hyun

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By Hyun Joo on Monday, June 7, 2004 - 09:22 am:

Additionally, I have one more question. When you use modifiers (acetic or formic acid, ammonium formate and sodium acetate, etc.) in B&J water and/or organic solvent mixtures, do you usually do filtering or not? We use the water from our picopure water system, not using commercial HPLC grade water. Any suggestion? Thank you.
Hyun

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By MG on Monday, June 7, 2004 - 02:11 pm:

I used to use water from a purification system, without additional filtering, but nowadays I buy it from B&J. I do not normally use sodium acetate, but with those others you list, I also use without filtration. As for which grades of solvents, I'll have to go back and look which kinds I order, as I don't have that info readily in front of me. For the acids and salts, I use the expensive, "ultra-pure" (or whatever) grades, but again I'd have to go back and look.

If you are using nylon filters, another option to try would be teflon filters, but it is difficult to get aqueous solutions to go through these.

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By Hyun Joo on Tuesday, June 8, 2004 - 06:14 am:

Hello MG,
Thank you for your valuable information. I will test B&J products for our LC/MS. Once you have the information that which kinds you order, could you post it for me? Thanks.
Hyun

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By Anonymous on Friday, June 11, 2004 - 01:42 am:

We have had a similar problem, the process of filtering (with nylon filters) gave us a huge background fluorescence reading - not good when you are trying to measure 0.25ng/ml :) . We stopped using as much plastic or filters as we could... ie not filtering the mobile phases, not using magnetic stirrers but shaking by hand followed by sonication to degas. etc... filters are evil things!.

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By HW Mueller on Friday, June 11, 2004 - 06:45 am:

Does anybody have data on interferences from regenerated cellulose (like Sartorius #18406-47-N)? I havn´t seen anything in UV or Fluorescence, but it´s easy to miss. Of course, we always reject the initial filtrate, if one does not do this one may also get more dust, and thus microbes, into the filtrate than one removes.