Since you are aware of your analytes molecular composition (low m.w.
alcohol) you can easily analyze carbon by ICPAES on a "monitoring"
Your major source of error or "Achilles heel" will be...your sample
introduction sysytem (SUPRISE!). Definite and unavoidable analyte
differentialtion will occur in the spray chamber desolvation process.
Equivalant weights of carbonate will give 10-1000 times less intensity
of something more volatile such as ethanol which will experience much
mure efficient desolvation and transport to the plasma. The 247 nm
wavelength will be fine (perfect) for your analysis.
Trace level analysis will be governed by analyte ID as mentioned
above. If you are sure that your anlyte ID is ethanol (or close) you
will be OK with carbon standards prepared with ethanol.
You will also observe a definite carbon backround from your argon.
Again, this is unavoidable so just monitor it for stability. It is
real and used by some manufacturers for monochrometer calibration.
ICP is nice for a quick check of carbon content but analyte
differentiation is a real concern.
Years ago I overcame trace level of organic carbon analysis by ICP
through a persulfate-heat promoted decomposition of organics in water,
collection into fixed volume, and direct injection into ICP carrier
gas for C emission meqsurements. The method worked very well with
excellant detection limits (0.01 ppm) which could go lower if I chose
larger sample volumes (5 ml only). If this is of interest I can send
you a copy of my paper but I do not belive you want to go that low.
The guys at CETAC (Omaha, NE-USA), did similiar work using a direct
injection nebulizer (DIN) which has no true desolvation process so the
sample differentiaition problem is avoided. It is a nice tool if you
can afford it.
Note: Don't forget that acidic solution will expell any dissoled carbonate
ethanol) and basic solution will absorb it(carbon dioxide) from the air.
drop of acid is sufficient to stabilize your samples (if nuetral) chemically
most likely biologically.
______________________________ Reply Separator
Subject: C in water by ICPAES
Author: "Oddvar Roeyset" <SMTP:[log in to unmask]> at chicago1
Date: 11/11/1999 7:20 AM
I am about to determine some organic additives (mostly lowmolecular
compounds) in natural water. I only need approximate valuesfor monitoring.
compounds are watersoluble and are present at concentrations at 1 -50%,
corresponding to a C-content from 1000 mg/L to (behold!) 200 000mg C/L
The water samples are rather clean, and contains usually only trace
concentrations of most common metals, so that spectral interferences are
I have an JarrelAsh IRIS Axial ICPAES, so my linear range is somewhat
compared to radial instruments.
Is there any useful C-lines which can be used for this concentration range?.
dont want to dilute, as I need to monitor some metals at trace
I have a C-I line at 193.3 nm, but this is rather sensitive, so it will
not work much above 10000 mg/L I am afraid. Is there any other
lines which are useful in the UV-VIS-range?. The NIST/PhysicsLab line
list several C-II,C-III,C-IV lines, and very few C/C-I-lines, but are these
CII-IV lines useful in ICPAES?
I would be very glad if someone would share experience with me about
low sensitive C-lines with working ranges from 1000 - 200 000 mgC/L.
I know that I probably will need an internal standard to take care of
effects, And it is probably neccessary to wind up the effect on the plasma.
good ideas for what effect on the plasma which is necessary to cope with 1
C ? We usually run water samples from 1000 - 1300 watts on a 27
Good ideas are welcome!. Thanks Oddvar Royset
Norwegian Institute Name : Oddvar Royset
for Water Research (NIVA) E-mail : [log in to unmask]
Brekkeveien 19 Phone : + 47 2218 5100
P.O.Box 173, Kjelsaas Fax : + 47 2218 5200
N-0411 Oslo, Norway Internet : http://www.niva.no