Glenn,
Bring this evidence of Kr to your supplier and see what they can do to
reduce the variability. Band-aids include using a correction equation
and/or calibrating and running samples off the same Ar bottle.
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 11:23:16 AM:
> 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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