By Anonymous on Friday, April 25, 2003 - 03:48 am:
Hi everyone,
I work with LC-MS (Agilent 1100 coupled to Bruker Esquire3000Plus) and I have a big problem with a contamination of m/z 391, which most likely is a plasticizer.
I run the HPLC system with H2O and ACN with different gradients. I tried also different vendors, but nothing changed.
Has anybody seen this contamination or knows where it comes from???
Thanks in advance
By Anonymous on Friday, April 25, 2003 - 05:08 am:
Which plastics your samples are in contact with?
Is it coming from the sample preparation or is it solvents/system related. You can test it by injecting neat solvent from rinsed vial without septa. You can also rule out the gradient solvents by running a gradient without injection.
You can try to extract possible sources (e.g. 1.syringe, 2.filter, 3.HPLC vial septa) in injection solvent for few hours. Inject these to see if the interfering peak rises. Ground joint grease, eppendorf vials and washing machine detergents are other possible sources.
Change to different material/supplier if you find the source.
Good luck.
By Anonymous on Friday, April 25, 2003 - 04:17 pm:
Dioctylphthalate?
By Tom Mizukami on Friday, April 25, 2003 - 04:17 pm:
One common plasticizer is dinonyl phthalate and will produce a peak at m/z 391, along with others. Do you see other peaks? 279, 149, etc?
By Anonymous on Monday, April 28, 2003 - 05:33 am:
Tom,
I also see the peak who have mentioned (m/z 279,149 and 803 = M2+Na+). Do you know if this plasticizer is used in PEEK tubing?
Anonymous,
Of course I did direct injection, but the problem is, that the ion trap is completely contaminated, so I see the masses always in the background.
It would be helpful to know where the plasticizer comes from. I think I can exclude the mobile phases.
By Chris Pohl on Monday, April 28, 2003 - 01:23 pm:
There is no plasticizer in PEEK tubing. Another possible source is your deionized water system. Does the water come in contact with "Tygon" tubing (i.e. clear vinyl tubing) on the outlet end? If so, this could be the source of your plasticizer.
By Anonymous on Monday, April 28, 2003 - 02:38 pm:
Confirmed, you're looking at phthalates. Rinse plasticware with isopropanol alcohol. Minimize use of low density polypropylene plasticware. Use nalgene or teflon plasticware. Another source could be from your Nitrogen, are you using a Nitrogen generator? If yes, you may have to install an extra trap on your Nitrogen line. I've also seen contamination from Helium going into the trap, you can also install an extra trap on the Helium line. The supplier of the Ion Trap should be able to help you with the kind of traps to purchase.
By Tom Mizukami on Monday, April 28, 2003 - 04:24 pm:
I agree with Chris and Anon above. PEEK does not contain phthalates. Most 'MilliQ' type of water systems are plumbed with teflon tubing which does not contain phthalates, however, many people put a length of tygon tubing on the outlet.
I have never tried to rinse plastic ware. We just try to be conscious about sources of phthalate contamination and eliminate them where we can. We documented the profile from a phthlate standard, and documented some of the sources above.
By Diana Beyer on Tuesday, July 1, 2003 - 02:21 am:
Hi,
I don't know if it's too late to answer.
I have the same problems with an Thermo Finnigan LCQ Advantage.
The phthalate peeks are coming from the membran of the acetonitrile channel of the degasser (build in the ms pump)and from from some gaskets.
So, they will exchange my degasser membranes and the gaskets that are in contact with acetonitrile.