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Na contents measure using Atomic absorption spectrometry
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Dr_Dickie
science forum beginner


Joined: 03 May 2005
Posts: 16

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: RE:Solid-Phase Extraction Reply with quote

Google it (also check out Supelco's web page--
http://www.sigmaaldrich.com/Brands/Supelco_Home.html )
Look at literature.
--
Dr. Dickie
Skepticult member in good standing #394-00596-438
Poking kooks with a pointy stick

"JP" <knps12@interia.pl> wrote in message
news:d07sqd$r7e$1@atlantis.news.tpi.pl...
Quote:
I'm looking for any materials on solid-phase extraction(SPE). Thanks in
advance.

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JP
science forum beginner


Joined: 29 Jul 2005
Posts: 27

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: RE:Solid-Phase Extraction Reply with quote

I'm looking for any materials on solid-phase extraction(SPE). Thanks in
advance.
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Biotech-lover
science forum beginner


Joined: 24 Mar 2005
Posts: 1

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Sign up for a great free science e-newsletter! Reply with quote

Hi there;
I sent an e-mail to that............but not responding.......
WHY??????????!!!!
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Henrietta
science forum beginner


Joined: 24 Mar 2005
Posts: 1

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Help : soil sampling Reply with quote

Hi. I happen to be married to a Soil Scientist. Did you extract the soil
solution from the sample or are you just measuring from a dry soild
sample? You need to measure what is called bulk density. You should
always do this reagrdless of what you will be doing with your soil. Bulk
density is a measure of the mass of soil per unit volume. It is useful
when comparing 2 soil horizons or types of soils becuase one of them may
be more compact than the other. Just do a google search for bulk density.
You also need to know the moisture content of the soil sample. It also
depends on what you are measuring, if you are looking at something like
NH4+, then it gets tricky beasue you have 2 sources: biological and
dissolved inorganic in the pore water. If you are looking at something
more inert, then you don't have to worry about the biological aspect of
your soil. Most results are reported in per mass of soil, not volume, and
knowing the bulk density will help you interpret your results. One last
thing, any soil scientist will tell you to always sample by soil horizon
(and not depth!) and composit your sample in the lab keeping some sample
from each horizon as a backup shold you want to know more about each.
Hope this helps.
-erika.
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labrat
science forum beginner


Joined: 12 May 2005
Posts: 18

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Al analysis Reply with quote

farooq_w@hotmail.com wrote in message news:<1107352580.171932.157220@o13g2000cwo.googlegroups.com>...
Quote:
Dieter Britz wrote:
What is a convenient method for analysis of Al in a solution
with pH ca. 7?

--
Dieter Britz, Kemisk Institut, Aarhus Universitet, Danmark.

Cheapest method could be complexometric titration with EDTA. The
expensive end for aluminum is atomic absorption method using
nitrous-oxide flame, if it occurs in trace quantities.

Unless the concentration of the Al is very low, Al at pH 7 will be in
the form of aluminium hydroxide polymers. If you have reasonable
concentrations of Al to measure (say g/L range), then we have a
simple, direct automated thermometric titration method. The Al is
titrated with standard sodium or potassium fluoride in the presence of
excess Na and K ions with the exothermic formation of insoluble
NaK2AlF6 ("elpasolite"). It is fast titration (ca. 2-3 minutes) and
highly precise, with CV's typically <0.1. The precision is in part due
to the Al:F stoichiometry of 1:6.

For low levels (say down to 10ppm), we have another automated
thermometric titration method. The Al (or any other trace metal) is
complexed with an excess of EDTA (say 0.01mol/L), the excess EDTA
being back-titrated with Cu(II) or Mn(II). The heat evolved is much
too small to be useful for a conventional thermometric endpoint, but a
catalytic indicator reaction provides a sharp increase in temperature.
The first trace of Cu(II) or Mn(II) past the endpoint catalyzes a
reaction between hydrogen peroxide and a polyhydric phenol such as
resorcinol.

For application notes on both procedures, contact
labrat@multitrator.com, and visit www.multitrator.com
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Guest






PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Al analysis Reply with quote

Dieter Britz wrote:
Quote:
What is a convenient method for analysis of Al in a solution
with pH ca. 7?

--
Dieter Britz, Kemisk Institut, Aarhus Universitet, Danmark.

Cheapest method could be complexometric titration with EDTA. The
expensive end for aluminum is atomic absorption method using
nitrous-oxide flame, if it occurs in trace quantities.
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Farooq W
science forum Guru Wannabe


Joined: 25 Mar 2005
Posts: 240

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Na contents measure using Atomic absorption spectrometry Reply with quote

Marvin wrote:
Quote:
bg wrote:
I am using atomic absorption spectrometry to measure Na contents in
arabidopsis. I am using spectra AA 220FS of varian. and I am using
K/Na
lamp. strange thing is K contents measure is oK no problem but when
I
try the Na contents measure, standard value and standard curve is
made
nicely but measure the sample the absolute value is not exact. when
I
check the Na contents using standard the absolute value is usually
higher than real value. I feel relative value is O.K but absolute
value
is different.

Can Someone help me.

Do a background correction. A flame containg sodium generates a
strong continuum background that
can mess up your analyses if a correction is not made.

Is there something special with flames containing sodium? Don't these
modern instruments auto-correct the background?
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beavith
science forum beginner


Joined: 19 May 2005
Posts: 23

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Na contents measure using Atomic absorption spectrometry Reply with quote

On 22 Mar 2005 23:20:11 -0800, "bg" <bgkimpeace@gmail.com> wrote:

Quote:
thank you very much

Did you do AAS in plant material?
If you used plant. let me know your protocol for extraction Na/K from
plant.

your comments should be very helpful.

thank you



for me it was industrial plating solutions. no serious organic
components to deal with.



Quote:
thankbeavith wrote:
On 18 Mar 2005 22:21:59 -0800, "bg" <bgkimpeace@gmail.com> wrote:

I am using atomic absorption spectrometry to measure Na contents in
arabidopsis. I am using spectra AA 220FS of varian. and I am using
K/Na
lamp. strange thing is K contents measure is oK no problem but when
I
try the Na contents measure, standard value and standard curve is
made
nicely but measure the sample the absolute value is not exact. when
I
check the Na contents using standard the absolute value is usually
higher than real value. I feel relative value is O.K but absolute
value
is different.

Can Someone help me

it goes back a couple of years, but i always ran atomic emission for
Na and K rather than atomic absorbtion, especially in Na rich samples
because you are zeroing in on the very narrow Na lines..
FWIW.
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beavith
science forum beginner


Joined: 19 May 2005
Posts: 23

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Na contents measure using Atomic absorption spectrometry Reply with quote

On 18 Mar 2005 22:21:59 -0800, "bg" <bgkimpeace@gmail.com> wrote:

Quote:
I am using atomic absorption spectrometry to measure Na contents in
arabidopsis. I am using spectra AA 220FS of varian. and I am using K/Na
lamp. strange thing is K contents measure is oK no problem but when I
try the Na contents measure, standard value and standard curve is made
nicely but measure the sample the absolute value is not exact. when I
check the Na contents using standard the absolute value is usually
higher than real value. I feel relative value is O.K but absolute value
is different.

Can Someone help me

it goes back a couple of years, but i always ran atomic emission for
Na and K rather than atomic absorbtion, especially in Na rich samples
because you are zeroing in on the very narrow Na lines..
FWIW.
Back to top
Guest






PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: RE:Solid-Phase Extraction Reply with quote

Dr_Dickie wrote:
Quote:
Google it (also check out Supelco's web page--
http://www.sigmaaldrich.com/Brands/Supelco_Home.html )
Look at literature.
--
Dr. Dickie
Skepticult member in good standing #394-00596-438
Poking kooks with a pointy stick

"JP" <knps12@interia.pl> wrote in message
news:d07sqd$r7e$1@atlantis.news.tpi.pl...
I'm looking for any materials on solid-phase extraction(SPE).
Thanks in
advance.


PLEASE CHECK OUT OUR WEB PAGE WWW.UNITEDCHEM.COM

- Don Shelly
Environmental Product Manager
United Chemical Technologies, Inc
1-800-541-0559
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bg
science forum beginner


Joined: 24 Mar 2005
Posts: 10

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Na contents measure using Atomic absorption spectrometry Reply with quote

Farooq W wrote:
Quote:
bg wrote:
I am using atomic absorption spectrometry to measure Na contents in
arabidopsis. I am using spectra AA 220FS of varian. and I am using
K/Na
lamp. strange thing is K contents measure is oK no problem but when
I
try the Na contents measure, standard value and standard curve is
made
nicely but measure the sample the absolute value is not exact. when
I
check the Na contents using standard the absolute value is usually
higher than real value. I feel relative value is O.K but absolute
value
is different.

Can Someone help me.

Most likely this is ionization interference since your results are
higher than the real value. The following might be a possible
explanation of your observation if your sodium standards do not
contain
potassium at all. As you know AA technique is based on absorption of
light by the population of ground state neutral atoms, note the
equilibria involved when you run the samples, since K is easily
ionized
than sodium, you have (i) K <----> K(+) + e, therefore the flame
being an electron rich environment reduces most of sodium ions, if
created in the flame at high temperature, to neutral sodium atoms by
(ii) Na(+) + e <------> Na, the equilibrium remains shifted to the
right from the ionization of potassium. This artificially increases
the
population of ground state neutral sodium atoms resulting in higher
absorbance and thus concentration.
Please note that this is merely a speculation.

Thank you very much for your kind reply.

Both of My standard and sample have highly concentrated K+.
Have you experience measure Na contents in plant or other sample.
Can you show me your protocol?
thank you very much
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Marvin
science forum Guru Wannabe


Joined: 24 Mar 2005
Posts: 224

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Na contents measure using Atomic absorption spectrometry Reply with quote

Farooq W wrote:
Quote:
Marvin wrote:

bg wrote:

I am using atomic absorption spectrometry to measure Na contents in
arabidopsis. I am using spectra AA 220FS of varian. and I am using

K/Na

lamp. strange thing is K contents measure is oK no problem but when

I

try the Na contents measure, standard value and standard curve is

made

nicely but measure the sample the absolute value is not exact. when

I

check the Na contents using standard the absolute value is usually
higher than real value. I feel relative value is O.K but absolute

value

is different.

Can Someone help me.


Do a background correction. A flame containg sodium generates a

strong continuum background that

can mess up your analyses if a correction is not made.


Is there something special with flames containing sodium? Don't these
modern instruments auto-correct the background?

Do they do it automatically, or do they just have the capability to do it when implemented?


Alkali metal atoms are easily ionized, so the electron number density in the flame gets large.
Electron-ion recombination causes a continuum background emission. How that affects an AA
measurement depends on the details of the instrument design and setup.

Another person suggested that it is better to measure alkali elements by flame emission than by AA.
Winefordner showed that years ago, but the makers of AA gear seem to have convinced many that AA
is always better. Flame emission with background correction is definitely the way to go for Na and K.
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bg
science forum beginner


Joined: 24 Mar 2005
Posts: 10

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Na contents measure using Atomic absorption spectrometry Reply with quote

thank you very much

Did you do AAS in plant material?
If you used plant. let me know your protocol for extraction Na/K from
plant.

your comments should be very helpful.

thank you




thankbeavith wrote:
Quote:
On 18 Mar 2005 22:21:59 -0800, "bg" <bgkimpeace@gmail.com> wrote:

I am using atomic absorption spectrometry to measure Na contents in
arabidopsis. I am using spectra AA 220FS of varian. and I am using
K/Na
lamp. strange thing is K contents measure is oK no problem but when
I
try the Na contents measure, standard value and standard curve is
made
nicely but measure the sample the absolute value is not exact. when
I
check the Na contents using standard the absolute value is usually
higher than real value. I feel relative value is O.K but absolute
value
is different.

Can Someone help me

it goes back a couple of years, but i always ran atomic emission for
Na and K rather than atomic absorbtion, especially in Na rich samples
because you are zeroing in on the very narrow Na lines..
FWIW.
Back to top
bg
science forum beginner


Joined: 24 Mar 2005
Posts: 10

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Na contents measure using Atomic absorption spectrometry Reply with quote

thank you very much

Did you do AAS in plant material?
If you used plant. let me know your protocol for extraction Na/K from
plant.

your comments should be very helpful.

thank you




thankbeavith wrote:
Quote:
On 18 Mar 2005 22:21:59 -0800, "bg" <bgkimpeace@gmail.com> wrote:

I am using atomic absorption spectrometry to measure Na contents in
arabidopsis. I am using spectra AA 220FS of varian. and I am using
K/Na
lamp. strange thing is K contents measure is oK no problem but when
I
try the Na contents measure, standard value and standard curve is
made
nicely but measure the sample the absolute value is not exact. when
I
check the Na contents using standard the absolute value is usually
higher than real value. I feel relative value is O.K but absolute
value
is different.

Can Someone help me

it goes back a couple of years, but i always ran atomic emission for
Na and K rather than atomic absorbtion, especially in Na rich samples
because you are zeroing in on the very narrow Na lines..
FWIW.
Back to top
Marvin
science forum Guru Wannabe


Joined: 24 Mar 2005
Posts: 224

PostPosted: Thu Mar 24, 2005 8:30 pm    Post subject: Re: Na contents measure using Atomic absorption spectrometry Reply with quote

bg wrote:
Quote:
I am using atomic absorption spectrometry to measure Na contents in
arabidopsis. I am using spectra AA 220FS of varian. and I am using K/Na
lamp. strange thing is K contents measure is oK no problem but when I
try the Na contents measure, standard value and standard curve is made
nicely but measure the sample the absolute value is not exact. when I
check the Na contents using standard the absolute value is usually
higher than real value. I feel relative value is O.K but absolute value
is different.

Can Someone help me.

Do a background correction. A flame containg sodium generates a strong continuum background that

can mess up youra analyses if a correction is not made.
Back to top
Google

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