| [Thread Prev] | [Thread Next] | [Thread Index] | [Date Prev] | [Date Next] | [Date Index] |
Dear Paleontologists,
A few weeks ago I asked for information about use of sodium polytungstate
(= Sodium metatungstate) as a heavy liquid, and I received many helpful
messages. Thank you all very much. I also found a few particularly useful
references that guide one through the practical pitfalls from mixing it to
cleaning up afterward. Tony Edwards suggested that I forward the whole
bundle to everyone, so here it is.
NUMBER: 88T-2127
AUTHOR: KRUKOWSKI, S. T.
AFFILIATION: Dept. of Geoscience, New Mexico Inst. of Mining & Tech.,
Socorro 87801, NM, USA.
TITLE: Sodium metatungstate: a new heavy-mineral separation medium
for the extraction of conodonts from insoluble residues.
JOURNAL: Journal of Paleontology, v62 n2, pp 314-316.
YEAR: 1988
LANGUAGE: English
ABSTRACT: Sodium metatungstate (3Na"SUB 2"WO"SUB 4".9WO"SUB 3".H"SUB
2"O) is a non-toxic, high-density (1.00-3.10 gm.cm"SUP -3")
separating compound which results in nearly neutral (pH 6)
solutions of relatively low viscosity. It has previously been
used as a medium for density gradient centrifigation. Since
then investigators have used SMT as a high-density medium for
routine mineral separations, for recovery of conodonts from
insoluble residues, for separation of various feldspar species
from one another, and for segregation of inorganic mineral
fractions (ash) from coal.-from Author
SUBJECT CODE: Geology
NUMBER: 93M-0786
AUTHOR: Commeau, J. A.; Poppe , L. J.; Commeau, R. F.
AFFILIATION: US Geological Survey, 582 National Center, Reston, VA 22092,
USA.
TITLE: Separation and identification of the silt-sized heavy-mineral
fraction in sediments.
JOURNAL: U.S. Geological Survey Circular, v1071, pp 13.
YEAR: 1992
LANGUAGE: English
ABSTRACT: The heavy minerals were separated using sodium polytungstate
liquid. The minerals were identified using SEM and energy-
dispersive XRF. Hundreds of particles were sized and sorted by
chemistry. The data are displayed by histograms and tables. -
K.A.R.
SUBJECT CODE: Geology
NUMBER: 94L-02165
AUTHOR: Robinson, S. M. C.; Chandler, R. A.
TITLE: An effective and safe method for sorting small molluscs from
sediment
JOURNAL: Limnology & Oceanography, v38 n5, pp 1088-1091
YEAR: 1993
LANGUAGE: English
ABSTRACT: Simple elutriation is used to remove less dense organic
detritus and a nontoxic compound (sodium polytungstate) is
used to create a heavy liquid that sorts the bivalves from
sediment by relative density. The technique was applicable to
12 species of molluscs of various sizes and was 98-100%
effective in separating juvenile Mya arenaria, ranging from
0.5-24 mm in shell length, from surrounding sediment. -from
Authors
DESCRIPTORS: mollusc; sediment; Mya arenaria
SUBJECT CODE: Ecology
NUMBER: 88R-2122
AUTHOR: GREGORY, M. R.; JOHNSTON, K. A.
AFFILIATION: Geol. Dept., Univ. of Auckland, Private Bag, Auckland, New
Zealand.
TITLE: A nontoxic substitute for hazardous heavy liquids - aqueous
sodium polytungstate (3Na"SUB 2"WO"SUB 4".9WO"SUB 3".H"SUB
2"O) solution. (Note).
JOURNAL: New Zealand Journal of Geology & Geophysics, v30 n3, pp 317-
320.
YEAR: 1987
LANGUAGE: English
ABSTRACT: Aqueous solutions of the salt sodium polytungstate can be
prepared with varying densities up to 3.1 g/cm"SUP 3". The
salt is nontoxic and it is recommended as a substitute for the
hazardous halogenated hydrocarbons, tetrabromoethane and
bromoform, customarily used in geological laboratories to
perform light/heavy mineral separations.-Authors heavy mineral
separations sodium polytungstate halogenated hydrocarbons
laboratory safety
SUBJECT CODE: Geology
------------------------------------------------------------------------
Comments: Converted from OV/VM to RFC822 format by PUMP V2.2X
Date: Fri, 15 Dec 95 14:30:28 EST
From: "J. Jett (c/o M. Buzas)" <MNHPB001@SIVM.SI.EDU>
Subject: Na polytungstate
To: <cbrunner@whale.st.usm.edu>
We've been using Na Polytungstate for a few years now and we have found
it to be just as good as the toxic stuff we used to use (as far as
recovery of forams goes) and it is much easier/nicer to work with. I use
the powder form and dilute it with distilled water (no set recipe, I
just add 'til the right minerals sink or float). Evaporation works fine
to recover the solution. Even when I forget it and it dries to a hard
chunk, I've been able to grind it up with a mortar and pestle and reuse
it. I was told when I first got it to store it only in plastic/Nalgene
bottles and beakers, no glass, although no one's told me why. I hope this
helps.
Martin A. Buzas, Curator, Museum of Natural History
Smithsonian Institution
Washington, D. C. 20560
Ph. (202) 357-1390 fax (202) 786-2832
-------------------------------------------------------
Date: Fri, 15 Dec 1995 13:37:30 -0600 (CST)
From: "C. Klug" <cklug@blue.weeg.uiowa.edu>
X-Sender: cklug@black.weeg.uiowa.edu
To: Charlotte Brunner <cbrunner@whale.st.usm.edu>
Subject: Re: non-toxic heavy liquids
On Fri, 15 Dec 1995, Charlotte Brunner wrote:
> Dear Paleontologists,
> Does anyone have experience using Na polytungstate that they are willing
> to share with me? Alternative does anyone know of other low-toxic heavy
liquids?
> I am deciding whether or not to buy some Na polytungstate to use in
> flotation of foraminifers. I asked a chemical company that sells it about
> adjustment of the specific gravity, and they were clueless. I assume that
> one just adds water to it until the density is reduced to the level desired.
We have been using sodium polytungstate for several years here at the
geology Department at the University of Iowa for the recovery of
conodonts. I much prefer it to TBE for safety reasons and because I
don't care for the smell of TBE. Sodium polytungstate is essentially
odor free (well, I can't smell it anyway). It is easily diluted with
water and can be used over a great range of densities. We use it at
specific gravities of 2.76 (when separating conodonts from quartz
residues) and 2.91 (for residues consisting mostly of dolomite rhombs).
One big problem with sodium polytungstate, however, is that the water you
use has to be essentially calcium-free. Calcium ions results in an
insoluble, often very finely crystalline precipitate (calcium
polytungstate?) that clouds the liquid, and depletes the sodium
polytungstate. As sodium polytungstate is very expensive, this is
generally considered to be a bad thing! If proper precautions are taken,
however, sodium polytungstate is nearly 100% recoverable. After a period
of over 5 years, we still had over 600 ml of usable sodium polytungstate
from an initial 1000 ml purchase.
> When using other heavy liquids, I adjust density with the appropriate
> solvent until a gypsum crystal (2.3) is neutrally bouyant.
We use a hydrometer designed for heavy liquids. This allows a great
deal of latitude in determining the densities. It is, however, another
initial investment. Also, they are very delicate and easily broken.
> The chemical can be purchased in liquid or powder form. Has anyone used
> the powdered form? Was there any problem diluting it with water? Is it
> readily soluble? The powder form is less expensive than the liquid form, but
> if the powder is difficult to use, then I would like to avoid it.
We have used both powdered and liquid. Both work fine and I have no
preference as to one or the other.
> I have some correspondence from Chris Barnes from years ago. He said that
> he evaporated the water to recover the Na polytungstate. He said that the
> last stage of evaporation goes fast and to be careful or I would end up with
> a cooked brick too hard to redissolve very well. Have you had this problem
> or any others?
Chris is right about the redissolving the brick. We use a drying
oven to evaporate the water off of the sodium polytungstate. For the
very dilute sodium polytungstate (essentially that recovered in the
rinsing stages of the process) I use a pyrex pie plate to evaporate the
water off. I completely evaporate the water off, which leaves a white
crust of sodium polytungstate on the pie plate. Usually, this
crust readily breaks into chips that I transfer to a beaker
partially filled with deionized water. These dissolve fairly quickly and
are long since dissolved by the time I have to recalibrate the working
sodium polytungstate solution. The only time I have formed the brick is
during the recalibration and, in trying to increase the density of a
beaker full of the stuff, have accidentally left it in the oven over
night. Next morning you find a beaker of solid polytungstate :( that's
where the real redissolving problem comes in.
> The stuff is, apparently, more viscous than some the more toxic and
> traditional heavy liquids like TBE. How long does it take to do a
> separation, 5 minutes, 1/2 hour, more?
We use a centrifuge to do our separations. Our centrifuges can hold
6- 50 ml (I believe) centrifuge tubes. Centrifuging only takes 10
minutes, but the washing the residues and tubes can make a residue of 200
ml take over an hour. Also, in our system, there is a backup in the
recovery of the used polytungstate and associated wash/rinse waters. We
use a vacuum pump to filter the above and the viscosity of the
polytungstate makes this a slow process, particularly if the residue is
clayey. The clay particles, obviously, clog up the filter making it very
slow going. This limits us to typically two or three samples per day.
If you are interested in a more detailed account as to our proceedure, I
think I have a copy on disk around here somewhere. It may take some
looking, but I'll be glad to do it if you think you will be going the
polytungstate route. Good luck!
Curt Klug
Department of Geology
The University of Iowa
Iowa City, Iowa 52242
home phone (319) 338:2572
dept. phone (319) 335-1818
e-mail: cklug@blue.weeg.uiowa.edu
------------------------------------------------------------
Date: Fri, 15 Dec 1995 11:51:43 -0800 (PST)
Date-Warning: Date header was inserted by OREGON.UOREGON.EDU
From: ehhaley@OREGON.UOREGON.EDU
Subject: Re: non-toxic heavy liquids
X-Sender: ehhaley@oregon-mailhost.uoregon.edu
To: cbrunner@whale.st.usm.edu
Hi Charlotte,
How are things? I'm still with the USGS, but am at a field office
at the University of Oregon for a little while. Anyway, about the sodium
polytungstate: I am in the process of ordering some to use for
concentrating sparse diatoms in glacial seds. David Harwood's group uses
it extensively for diatoms, and I think it is what will work best for me.
As I understand things, the SPT is in a powder form that is diluted with
water until the proper specific gravity is acquired. I fully expect to
have to experiment to get this right, but it doesn't sound too difficult.
There is a paper by Norm Savage in the Journal of Micropaleo that discusses
his SPT method for separating conodonts. Perhaps that would help:
N.M. Savage, 1988, J. micropaleontol., 7(1):39-40.
Besides being non-toxic, SPT is apparently re-usable, as you can dry the
remaining liquid back to crystal form for another use. That's good news
for me since it is relatively expensive.
Good luck --
EH-H
----------------------------------------
Eileen Hemphill-Haley
U.S.G.S. c/o 1272 Geological Sciences
University of Oregon
Eugene OR 97403-1272
eileen@octopus.wr.usgs.gov
ehhaley@oregon.uoregon.edu
(541) 346-4582 / FAX 541-346-4692
--------------------------------------------------------------------
Date: Fri, 15 Dec 1995 13:58:58 -0600
From: amm0001@Okway.okstate.edu (Darwin Boardman)
Subject: Re: non-toxic heavy liquids
To: Charlotte Brunner <cbrunner@whale.st.usm.edu>
Content-Description: cc:Mail note part
Dear Charlotte Brunner,
I have not used them myself but Glen Merrill at the University of Houston
Downtown Houston is very fimilar with the process. My main concern in their use
was the extremely high cost. Hope this works out for you.
Darwin
_______________________________________________________________________________
Subject: non-toxic heavy liquids
From: Charlotte Brunner <cbrunner@whale.st.usm.edu> at SMTP
Date: 12/15/95 10:23 AM
Dear Paleontologists,
Does anyone have experience using Na polytungstate that they are willing
to share with me? Alternative does anyone know of other low-toxic heavy liquids?
I am deciding whether or not to buy some Na polytungstate to use in
flotation of foraminifers. I asked a chemical company that sells it about
adjustment of the specific gravity, and they were clueless. I assume that
one just adds water to it until the density is reduced to the level desired.
When using other heavy liquids, I adjust density with the appropriate
solvent until a gypsum crystal (2.3) is neutrally bouyant.
The chemical can be purchased in liquid or powder form. Has anyone used
the powdered form? Was there any problem diluting it with water? Is it
readily soluble? The powder form is less expensive than the liquid form, but
if the powder is difficult to use, then I would like to avoid it.
I have some correspondence from Chris Barnes from years ago. He said that
he evaporated the water to recover the Na polytungstate. He said that the
last stage of evaporation goes fast and to be careful or I would end up with
a cooked brick too hard to redissolve very well. Have you had this problem
or any others?
The stuff is, apparently, more viscous than some the more toxic and
traditional heavy liquids like TBE. How long does it take to do a
separation, 5 minutes, 1/2 hour, more?
Thanks in advance for your help.
Cheers, CB
Charlotte A. Brunner
Center for Marine Sciences
The University of Southern Mississippi
Bld. 1103, Rm. 102
John C. Stennis Space Center
MS 39529
Office phone: 601-688-3402
Dept. phone: 601-688-3177
FAX: 601-688-1121
Internet: cbrunner@whale.st.usm.edu
---------------------------------------------------------------------
Date: Fri, 15 Dec 1995 14:25:20 PST
From: noblepj@CCVAX.CCS.CSUS.EDU
To: cbrunner@whale.st.usm.edu
Subject: RE: non-toxic heavy liquids
>Dear Paleontologists,
> Does anyone have experience using Na polytungstate that they are willing
>to share with me? Alternative does anyone know of other low-toxic heavy
liquids?
> I am deciding whether or not to buy some Na polytungstate to use in
>flotation of foraminifers. I asked a chemical company that sells it about
>adjustment of the specific gravity, and they were clueless. I assume that
>one just adds water to it until the density is reduced to the level desired.
>When using other heavy liquids, I adjust density with the appropriate
>solvent until a gypsum crystal (2.3) is neutrally bouyant.
> The chemical can be purchased in liquid or powder form. Has anyone used
>the powdered form? Was there any problem diluting it with water? Is it
>readily soluble? The powder form is less expensive than the liquid form, but
>if the powder is difficult to use, then I would like to avoid it.
> I have some correspondence from Chris Barnes from years ago. He said that
>he evaporated the water to recover the Na polytungstate. He said that the
>last stage of evaporation goes fast and to be careful or I would end up with
>a cooked brick too hard to redissolve very well. Have you had this problem
>or any others?
> The stuff is, apparently, more viscous than some the more toxic and
>traditional heavy liquids like TBE. How long does it take to do a
>separation, 5 minutes, 1/2 hour, more?
> Thanks in advance for your help.
>
Charlotte,
I have had some limited experience with the stuff on conodont separations
when I worked with Davey Jones. I know that the Berkeley Geochronology
Group (i.e. Paul Renne and Carl Swisher etc.) uses it extensively.
It is a bit of a pain because evaportaion does change the density significantly,
and it is viscous, so muddy or fine grained residues take a day or two to
settle, and in that time, you must guard against evaporation. For your
material, plan on starting it in the morning and checking back after about
4 - 6 hours.
I've used both powder and as premixed. It isn't hard to mix the frist time,
but the recovery and recycling is trickier. Mixing can be done by pre-weighing
the glassware you are recovering in and reconstituting later via mass
calculations.
The good news is the non toxicity. If you decide to go with it, you may want
to talk to Paul Renne and co. about their experiences.
Regards,
Paula Noble
Geology Dept.
CSU Sacramento
Sacramento, CA 95819-6043
--------------------------------------------------------------------
Date: Fri, 15 Dec 95 15:17:58 PST
Errors-To: jlipps@ucmp1.Berkeley.EDU
Reply-To: ewan.fordyce@stonebow.otago.ac.nz
Originator: micropal@ucmp1.berkeley.edu
Sender: micropal@ucmp1.Berkeley.EDU
Precedence: bulk
From: ewan.fordyce@stonebow.otago.ac.nz (ewan fordyce)
To: cbrunner@whale.st.usm.edu
Subject: Re: non-toxic heavy liquids
X-Listprocessor-Version: 6.0b -- ListProcessor by Anastasios Kotsikonas
X-Comment: micropaleontogy mailing list
Re: query by Charlotte A. Brunner on Na polytungstate for floating forams -
I sought to use polytungstate as an alternative to carbon tetrachloride
because of multiple hazards associated with CCl4. But, a sedimentologist
here advised strongly against Na polytungstate on the grounds that it
gradually exchanges Na for Ca from foram tests and other sources of Ca,
leading to insoluble Ca polytungstate precipitates. The sedimentologist
had that very problem using poly-t with calcite-bearing greensands. [Maybe
a chemically-minded minded micropal subscriber can offer more details.]
There are a few references around on general uses of polytungstate,
particularly in sedimentological journals. One that springs to mind is -
Gregory, M. R., and Johnston, K. A. 1987. A nontoxic substitute
for hazardous heavy liquids - aqueous sodium polytungstate
(3Na2WO4.9WO3.H2O) solution (note). New Zealand journal of geology and
geophysics 30 (3): 317-320.
Currently I use chloroform for floating forams. This harmful presumed
ozone depleter seems to be a better alternative than 'traditional' heavy
liquids such as TBE or CCl4. Chloroform seems only to float tests with
minimal infills, though.
Regards,
Ewan
R. Ewan Fordyce, Associate Professor
Department of Geology, University of Otago, PO Box 56, Dunedin, NZ
fax 64-3-479-7527, ph. 64-3-479-7510
---------------------------------------------------------------
X-Sender: ucfbjpd@pop-server.bcc.ac.uk
Date: Mon, 18 Dec 1995 11:08:14 +0000
To: cbrunner@whale.st.usm.edu
From: ucfbjpd@ucl.ac.uk (Phil Dolding)
Subject: Re: non-toxic heavy liquids
Dear Charlotte,
I am a palynologist, so maybe my experience of Na-Polytung.
is of little interest to you.
However, for your information, I've had excellent results
using it for paly. preps.
I only used thin rubber gloves & it can be sieved to remove
any debris in it & then reused. You can also set the specific
gravity of it very accurately.
I found I had to wash the pal residues thoroughly though, as it
is quite viscous.
Hope this is of some help,
Best wishes
Phil Dolding
UCL
London
...in haste....
...submitting PhD today.....
Charlotte A. Brunner
Center for Marine Sciences
The University of Southern Mississippi
Bld. 1103, Rm. 102
John C. Stennis Space Center
MS 39529
Office phone: 601-688-3402
Dept. phone: 601-688-3177
FAX: 601-688-1121
Internet: cbrunner@whale.st.usm.edu
Partial index: