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PLASMACHEM-L  September 2011

PLASMACHEM-L September 2011

Subject:

Re: FW: Mass 82

From:

"Pappas, Richard Steve (CDC/ONDIEH/NCEH)" <[log in to unmask]>

Reply-To:

PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's).

Date:

Fri, 30 Sep 2011 13:14:19 +0000

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (1 lines)

No worries, Duane,

I consider not being able to remember what I said is an advantage that I can blame on age. A number of politicians have avoided self-incrimination by being unable to recall...



R. Steven Pappas, Ph.D.

Smoke Analysis Group

Centers for Disease Control & Prevention

4770 Buford Hwy, M.S. F-44

Atlanta, GA USA 30341-3717

770-488-4661

[log in to unmask]



-----Original Message-----

From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). [mailto:[log in to unmask]] On Behalf Of Duane Miller

Sent: Friday, September 30, 2011 9:05 AM

To: [log in to unmask]

Subject: Re: FW: Mass 82



Nice approach.  Let's hope Glenn's distributor can follow your line of 

reasoning.  (Steve, I'm really not that clever.  I didn't realize what I 

wrote until I read it.)



Duane Miller

Analytical Lab Manager

APL Engineered Materials, Inc.

Urbana, IL 61802

[log in to unmask]



"PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's)." 

<[log in to unmask]> wrote on 09/29/2011 09:25:08 PM:



> Hi Glenn,

> 

> Even though your supplier doesn't seem to agree, by now several list

> members convinced us that the culprit to your problem with M82 is 

> most likely to be Kr present in argon. However, you still may have a

> hard time convincing your supplier that it is the case. I thought 

> the following calculation (and a plot) using the data you provided 

> us may give you good ammunition (which was also interesting and 

> educational for me):

> 

> I calculated the difference as T2-T1(in Col-3 below) of the two 

> background measurements that you made at different masses using two 

> different tanks (in col-1 and col-2). Irrespective of the magnitude 

> of the background at a particular mass, this difference T2-T1 should

> disappear for any background which remain almost constant and NOT 

> related to the "tanks", NOR due to Kr(For example, ArCl+, Ar2+, 

> noise, etc.). I have also tabulated the corresponding Natural 

> Abundances of Kr isotopes in col-4 (Note that, Kr80 was omitted as 

> we do not have counts at M80). Col-5 lists only those T2-T1 

> values(taken directly from col-3) only for the masses where Kr 

> isotopes are present(for convenience of plotting).

> 

> Mass  col-1  col-2   col-3         col-4         col-5

> 

>       Tank1  Tank2   T2 -T1        Kr            T2-T1 from

> 

>                      (net cts)     Abundance     col-4 for

> 

>                                                  Kr masses

> -----------------------------------------------------------

> 

> 77      3.4    3.9      0.5

> 78    613    628       15           0.35          15

> 79    129    132        3

> 81    222    223        1

> 82     69    593      524          11.6          524

> 83     70    597      527          11.5          527

> 84    356   3036     2680          57           2680

> 85      9.2   18        8.8

> 86    113    954      841          17.3          841

> 87     12     14        2

> -----------------------------------------------------------

> 

> 

> 

> Now, in EXCEL if you plot Col-5 versus Col-4 (last two columns), in 

> spite of possible significant statistical fluctuation of small 

> numbers, you will still see a near perfect straight line with a 

> correlation coefficient of 0.9998 (attachments are not allowed); 

> where five isotopes of Kr together are proving that the "tank-to-

> tank" variation at M82 that you observed IS in fact due to Kr. You 

> may do the same for other tanks as well to further strengthen your case.

> 

> 

> 

> Interestingly, major portion of the highest observed background 

> counts at M78 (613 and 628; very little from Kr) and at M81 (222 and

> 223, is not from Kr) remain virtually the same in the two tanks, 

> giving very small difference T2-T1 for those masses.

> 

> 

> 

> Conversely, it looks like you may be able to use different tanks 

> from the particular supplier, to confirm the natural abundances of 

> Kr isotopes :)

> 

> 

> 

> Hope this is useful.

> 

> Regards,

> 

> 

> 

> Nimal

> 

> ***********************************************

> Dr. Nimal De Silva

> Department of Earth Sciences

> University of Ottawa

> Ottawa, Ontario

> Canada K1N 6N5

> Phone: 613-562-5800 ext 6843

> Fax: 613-562-5192

> E-mail: [log in to unmask]

> ***********************************************

> 

> ________________________________________

> From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). 

> [[log in to unmask]] on behalf of Steve Wilbur [steven.

> [log in to unmask]]

> Sent: September 29, 2011 4:56 PM

> To: [log in to unmask]

> Subject: Re: Mass 82

> 

> Hi Glenn,

> 

> You have encountered a problem that we have all suffered 

> intermittently over the years.  Liquid argon won't solve it, in fact

> it may be worse.  As Johan has said, the problem is that there is 

> always some Kr in Ar, and since it is both heavier and has a higher 

> boiling point, it is always the last thing left at the bottom of the

> dewar when the argon is used up.  If the dewar isn't correctly 

> evacuated before refilling, then the Kr begins to accumulate.  This 

> can happen in the dewar at your site or the one at the supplier from

> which they fill the high pressure cylinders.  Hence the problem with

> both dewars and cylinders, though in my experience cylinders tend to

> show much lower Kr background than what we have seen in some dewars.

> Talk with your supplier and let them know that the Kr is a problem 

> for ICP-MS.  It isn't a problem for most uses of liquid or 

> pressurized Ar, so they may not even know.

> 

> Best regards,

> 

> Steve Wilbur

> Agilent Technologies

> 

> 

_______________________________________________________________________________________________________

> Steve Wilbur | Senior Applications Chemist, ICP-MS Systems | Agilent

> Technologies, Chemical Analysis Solutions Unit |

> 1615 75th Street SW, Suite 210, Everett, WA 98203-6261 | (t:425.356.

> 6333 | : 360-468-3683 | :: [log in to unmask]

> 

> -----Original Message-----

> From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). [mailto:

> [log in to unmask]] On Behalf Of James Neal-Kababick

> Sent: Thursday, September 29, 2011 10:29 AM

> To: [log in to unmask]

> Subject: Re: Mass 82

> 

> The values at 82, 83, 84, and 86 being elevated like that do support

> Kr variability as mentioned.  Why are you not able to get liquid 

> argon?  That would probably greatly eliminate your problem even if 

> you had to make a long run from the Dewar to the instrument. 

> Perhaps the other option is to look at using a six-pack of argon 

> cylinders with one feed so that you have six bottles of one lot.  At

> least that way you can run for a longer period before switch over 

> and if you have two of those delivered (one six pack on each line) 

> of the same lot then you would have twelve bottles from the same 

> lot.  That would greatly reduce your drift problem interval.

> 

> 

> Sincerely,

> 

> James Neal-Kababick

> Director

> Flora Research Laboratories

> An FDA and DEA Registered & Inspected Laboratory

> Fellow AOAC International

> Adjunct Faculty Bastyr University

> Botanical Medicine Department

> [log in to unmask]

> www.floraresearch.com

> 

> 

> CAUTION:

> This e-mail and its accompanying attachments, if any,  may contain 

> information that is confidential and subject to legal privilege. If 

> you are not the intended recipient, you are notified that any use, 

> dissemination, distribution or copying of this message is 

> prohibited. If you have received this  message in error, please 

> notify Flora Research Laboratories immediately and destroy all 

> copies of this message and the accompanying attachments. Thank you.

> 

> 

> 

> -----Original Message-----

> From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). [mailto:

> [log in to unmask]] On Behalf Of Hyland, Glenn

> Sent: Thursday, September 29, 2011 9:23 AM

> To: [log in to unmask]

> Subject: Re: Mass 82

> 

> Hi Duane.  I got these counts (0.1s integration) from two different 

> tanks from two different lots aspirating 18.3 megaOhm water.

> 

>         Tank1           Tank2

> 77      3.4             3.9

> 78      613             628

> 79      129             132

> 81      222             223

> 82      69              593

> 83      70              597

> 84      356             3036

> 85      9.2             18

> 86      113             954

> 87      12              14

> 

> Based on what Ed mentioned and the counts at 84 and 86 it would seem

> that there is some Kr variability at a minimum.

> 

> Glenn

> 

> 

> Glenn Hyland

> Public Health-Madison & Dane County

> 210 MLK Jr Blvd, Room 507

> Madison, WI 53703

> 608-243-0348

> 

> 

> 

> 

> -----Original Message-----

> From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's). [mailto:

> [log in to unmask]] On Behalf Of Duane Miller

> Sent: Thursday, September 29, 2011 9:57 AM

> To: [log in to unmask]

> Subject: Re: Mass 82

> 

> Glen,

> 

> A mass spectrum from 77 to 87 (skip 80) would be helpfull in identifying

> the species at mass 82 in each of your cylinders.

> 

> Duane Miller

> Analytical Lab Manager

> APL Engineered Materials, Inc.

> Urbana, IL 61802

> [log in to unmask]

> 

> "PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's)."

> <[log in to unmask]> wrote on 09/29/2011 09:25:43 AM:

> 

> >   We are running an Agilent 7500ce and have recently had problems

> > with Se at 82.  We run EPA 200.8 for most samples so we must use

> > mass 82 and no collision/reaction gases.  We have a two cylinder

> > automatic switchover manifold and use grade 5 Ar as we are unable to

> > get liquid Ar delivered to our facility.  The problem first

> > presented itself as calibration blanks run every 10 samples being

> > quite positive or negative out of range (-idl<concentration<+idl)

> > during a long run.  I was able to determine this happened after a

> > tank switch over.  To try and accommodate this I warmed up and tuned

> > on one tank and switched to a new tank just prior to calibration.

> > This worked for some time.  Now I am experiencing a drift in the 82

> > signal during a tank too.  Yesterday, I began to monitor counts at

> > 82 during warm up.  I had 73 at mass 82 on the first tank.  I

> > manually switched to another tank and the counts went up to 1400.  I

> > put a third tank on and manually switched to it and the counts were

> > about 800.  The change in signal was instantaneous with the

> > changeover each time.  All 3 of these tanks were from different lots.

> >   I have seen many discussions here about Kr being present and

> > accumulating in dewars but I couldn't find any discussions about Kr

> > in cylinders.  I talked with the supplier and they felt Kr wouldnt

> > be an issue because it wouldn't be liquefied in the tank at that

> > pressure so it wouldn't accumulate in the tanks nor would the tank

> > be stratified either.  The supplier also felt since Kr is present at

> > low levels in the atmosphere that the proportion in their gases

> > would end up being relatively constant across lots.  In looking

> > around the only other instance of problems I have found at 82 was

> > Br81H+.  I am not sure if Br is checked in grading the gas or not

> > and haven't taken it up with the supplier yet.  Has anyone else

> > experienced this sort of thing or have any suggestions?  Thanks in

> advance.

> >

> > Glenn

> >

> >

> > Glenn Hyland

> > Public Health-Madison & Dane County

> > 210 MLK Jr Blvd, Room 507

> > Madison, WI 53703

> > 608-243-0348



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