MicrobeHunter.com Microscopy Forum

You can also access this page with: www.microscopy-forum.com
It is currently Sat Aug 17, 2019 5:04 pm

All times are UTC




Post new topic  Reply to topic  [ 24 posts ] 
Author Message
 Post subject: Diatom cleaning attemp
PostPosted: Tue Aug 14, 2018 10:20 am 
Offline
User avatar

Joined: Fri Jun 02, 2017 12:05 pm
Posts: 75
Location: Memphis, Tn., US
Inspired by the current thread on mild cleaning and incineration of diatoms, I decided to try it minus incineration for now.
This sample was centrifuged with a 4:1 3% H2O2 / distilled water solution for three minutes, mixed and allowed to sit over night, then rinsed multiple times. Thanks for the inspiration guys. I knew if I hung out here some I learn stuff.
Not professional at all, but I'm very tickled with my first attempt.


Attachments:
IMG_14-08-20188545-003.JPG
IMG_14-08-20188545-003.JPG [ 166.42 KiB | Viewed 1563 times ]

_________________
"You're never too old to have a happy childhood"
Leitz Wetzlar SM-LUX
Olympus IM
Canon 450D
Top
   
PostPosted: Tue Aug 14, 2018 1:20 pm 
Offline
User avatar

Joined: Sat Jun 18, 2016 11:55 am
Posts: 948
Location: Arnold, Missouri USA
Nice job!
I’ve only tried this once, but it was a disaster.
Another day perhaps.

_________________
Arnold, Missouri
Olympus IX70 HMC
Olympus BX40 Phase Contrast
Olympus SZ40 Stereoscope


Top
   
PostPosted: Tue Aug 14, 2018 7:21 pm 
Offline

Joined: Mon Aug 21, 2017 9:02 pm
Posts: 1956
Good luck! Once you pass the initial bumps, and work safely, you are on the road to enjoyment. Plenty of information about it here and in many other sources when you want it. Specifically, two recent detailed and well documented works are "Doing Diatoms a Different Way" (OP Charles) started Nov 29, 2016, and "Doing Diatoms" (OP rnabholz) started May 15, 2016.

_________________
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo


Top
   
PostPosted: Wed Aug 15, 2018 9:07 am 
Offline

Joined: Thu Aug 03, 2017 10:28 am
Posts: 111
Location: UK
Yes, cleaning diatoms can be fun, and there are many well tried and tested methods.

It may be worth interested parties looking at this resource, where amateurs of both great and little experience describe a number of methods, including hot acid protocols, but also the gentler methods, and some newly tried commercial cleaning products.

http://www.diatoms.co.uk/ad/archive.htm


Top
   
PostPosted: Wed Aug 15, 2018 10:18 pm 
Offline

Joined: Mon Nov 10, 2014 10:01 pm
Posts: 2871
photomicro wrote:
Yes, cleaning diatoms can be fun, and there are many well tried and tested methods.

It may be worth interested parties looking at this resource, where amateurs of both great and little experience describe a number of methods, including hot acid protocols, but also the gentler methods, and some newly tried commercial cleaning products.

http://www.diatoms.co.uk/ad/archive.htm


I had forgoten about this site.. Thanks for the memory jog!...

BillT


Top
   
PostPosted: Thu Aug 16, 2018 9:13 am 
Offline
User avatar

Joined: Fri Jun 02, 2017 12:05 pm
Posts: 75
Location: Memphis, Tn., US
Thanks for the encouraging words guys. It is indeed an enjoyable and educational pursuit for me. Perhaps in the not too distant future I can graduate to a little more involved and harsher chemical cleaning. For now I'll continue exploring H2O2
methods. Thanks for the great link photomicro.

_________________
"You're never too old to have a happy childhood"
Leitz Wetzlar SM-LUX
Olympus IM
Canon 450D


Top
   
PostPosted: Sat Aug 18, 2018 2:47 am 
Offline
User avatar

Joined: Thu Jan 08, 2015 10:11 pm
Posts: 3066
Location: Iowa USA
Hi jimur

I find the acids very intimidating, and so stayed away.

I have had very good results from H2O2 in the 30% strength teamed with Potassium Dichromate. Both require caution, but the H2O2 is relatively safe, minor temporary bleaching of exposed skin (20 minutes).

The PD is a powerful oxidizer, but used in very small amounts in large containers is manageable. Avoid the fumes and contact with the skin.

More on my experiences in the "Doing Diatoms" thread.

Keep up the good work.

_________________
Rod Nabholz
http://www.homebuiltastronomy.com
http://www.wildsideiowa.com


Top
   
PostPosted: Sat Aug 18, 2018 7:58 am 
Offline
User avatar

Joined: Fri Jun 02, 2017 12:05 pm
Posts: 75
Location: Memphis, Tn., US
rnabholz wrote:
Hi jimur

I find the acids very intimidating, and so stayed away.

I have had very good results from H2O2 in the 30% strength teamed with Potassium Dichromate. Both require caution but..........


Thanks for the info Rod. I may just try and locate the higher strength H2O2. Isn't PD used in developing by some photographers who shoot film? The name sounds familiar.

_________________
"You're never too old to have a happy childhood"
Leitz Wetzlar SM-LUX
Olympus IM
Canon 450D


Top
   
PostPosted: Sat Aug 18, 2018 11:32 am 
Offline
User avatar

Joined: Thu Jan 08, 2015 10:11 pm
Posts: 3066
Location: Iowa USA
You might be able to find higher the concentration H2O2 locally at a health food store. I order mine from Amazon.

Yes, Potassium Dichromate is used in photographic processing among other uses. I found mine in a reasonable quantity on Ebay. You will not need much, as it doesn't take much to get the reaction we are after. A half a baby aspirin sized dose in a 100ml's of H202/diatom batch is all it takes, and I suggest a 500ml or larger beaker and a catch tray to safely contain the reaction. You definitely don't want to do this in a test tube.

Be patient waiting for the reaction, it can sometimes take a bit for it to kick off. Resist the urge to add more PD. I have had it take an hour or longer to start, and I have seen it take less than a minute. Weird, but adding more PD can cause it to get pretty exciting when it goes, and not good exciting... That is where the catch tray comes in.

The reaction usually is over in a couple of minutes, bubbling, heat and steam, yielding an orange solution. From there it is just a matter of multiple rinses to clear and you are all set.

Rod

_________________
Rod Nabholz
http://www.homebuiltastronomy.com
http://www.wildsideiowa.com


Top
   
PostPosted: Sat Aug 18, 2018 7:49 pm 
Offline

Joined: Mon Aug 21, 2017 9:02 pm
Posts: 1956
I wonder, was it ever demonstrated that the addition of dichromate to H2O2 at the final stage of cleaning diatoms is significant and essential? I have seen this trick in the Sterrenburg Protocol, perhaps in other protocols as well, and I have read that is was successfully applied as described in the (very interesting) posts "Doing Diatoms" and "Doing Diatoms A Different way" in the forum. Yet I have a reservation, perhaps unjustified.
It is known that dichromate reacts chemically with H2O2, irrespective of diatoms and other organic chemicals. So, effervescence, froth, rapid heating etc are expected, at least due to the reaction between the dichromate and surplus, unreacted H2O2. Thus dichromate gets rid of the unused excess of H2O2 in the flask, but does it also serve as cleaner? does it eliminate organic stuff and debris, which previous heating or even boiling with H2O2 did not decompose?
Because (and I now enter a fox-hole against incoming sling-rocks and comments) I believe that there are safer ways than the dichromate to get rid of the excess H2O2.

_________________
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo


Top
   
PostPosted: Sat Aug 18, 2018 8:34 pm 
Offline

Joined: Thu Aug 03, 2017 10:28 am
Posts: 111
Location: UK
Hobbyst46 wrote:
I wonder, was it ever demonstrated that the addition of dichromate to H2O2 at the final stage of cleaning diatoms is significant and essential? I have seen this trick in the Sterrenburg Protocol, perhaps in other protocols as well, and I have read that is was successfully applied as described in the (very interesting) posts "Doing Diatoms" and "Doing Diatoms A Different way" in the forum. Yet I have a reservation, perhaps unjustified.
It is known that dichromate reacts chemically with H2O2, irrespective of diatoms and other organic chemicals. So, effervescence, froth, rapid heating etc are expected, at least due to the reaction between the dichromate and surplus, unreacted H2O2. Thus dichromate gets rid of the unused excess of H2O2 in the flask, but does it also serve as cleaner? does it eliminate organic stuff and debris, which previous heating or even boiling with H2O2 did not decompose?
Because (and I now enter a fox-hole against incoming sling-rocks and comments) I believe that there are safer ways than the dichromate to get rid of the excess H2O2.



It is surely a stronger oxidising agent, hence should clear some of the organic material left.

As regards getting rid of unused peroxide, a simpler way of doing this is just to leave it, as it will eventually decompose into water and oxygen over time. You would remove excess chemicals left by several rinses with distilled (or similar) water, especially as you don't want any residues before mounting.

This is a good reference if you have not seen it before;

https://www.mccrone.com/mm/an-introduct ... diatoms-2/

Mike


Top
   
PostPosted: Sat Aug 18, 2018 10:00 pm 
Offline

Joined: Mon Aug 21, 2017 9:02 pm
Posts: 1956
photomicro wrote:
It is surely a stronger oxidising agent, hence should clear some of the organic material left.
Thanks a lot for the link to the McCrone book! I already scanned it looking for the dichromate role! but found no explanation.
AFAIK, dichromate is a strong oxidizer at strong acidic pH. However, I guess that the pH of the diatom suspension in H2O2 is fairly neutral. The composition and processes in mixtures of dichromate and H2O2 depend on the pH and are quite complex. Surely some drastic interaction occurs upon the addition of the (tiny) amount of dichromate, but who is the oxidizing agent in the mixture? and did it oxidize diatoms or other unwanted material? This is perhaps tinkering or "digging", yet...

_________________
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo


Top
   
PostPosted: Sat Aug 18, 2018 10:13 pm 
Offline
User avatar

Joined: Thu Jan 08, 2015 10:11 pm
Posts: 3066
Location: Iowa USA
Regarding the necessity of potassium dichromate in the process, I can't say that I have done extended study, but there is basis for it in the work of folks much smarter than me.

I found the process while searching for an alternative to drain cleaner which was a fail for me. I came up in an academic paper, and credited Albert van Der Werff as the originator. Searching his name + dichromate will bring up references, most of which seem to be behind pay walls.

For what it's worth.

Rod

_________________
Rod Nabholz
http://www.homebuiltastronomy.com
http://www.wildsideiowa.com


Top
   
PostPosted: Sat Aug 18, 2018 10:27 pm 
Offline

Joined: Mon Aug 21, 2017 9:02 pm
Posts: 1956
Thanks Rod - I will try and search. Curiosity killed the cat... ;)

_________________
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo


Top
   
PostPosted: Sat Aug 18, 2018 11:13 pm 
Offline
User avatar

Joined: Sat Jun 20, 2015 3:57 am
Posts: 2703
Location: Houston, Texas
Hobbyst46,

If you are boiling 30% H2O2, I don't think you have to try dichromate. Dichromate is supposed to help oxygen production, which is what boiling does as well. I am not 100% sure, though I am guessing it dichromate + 30% H2O2 may provide more oxidation. Your boiling results look good enough though, such that you likely don't need dichromate.

I personally would prefer boiling as it involves less harmful chemicals and is a chemically simpler process. You would want eventually to remove trace dichromate as it is toxic, but trace H2O2 would disintegrate itself.

I had quite some chemistry courses in college to be very comfortable with it, but I am no chemist by trade. Member eiman is a good chemist, if you need to ask to be sure.


Top
   
PostPosted: Sun Aug 19, 2018 12:49 am 
Offline
User avatar

Joined: Tue Jun 09, 2015 12:08 am
Posts: 1501
Location: League City, Texas
Hey Rod, good to see you -- sure miss your diatom images!

I pick up food grade 35% H202 at a local health food store/cafe, and am perfectly satisfied with the results I get.

_________________
Cheers,
Kurt Maurer
League City, Texas
email: ngc704(at)aol(dot)com
http://sawdustfactory.nfshost.com/microscopes/
https://www.flickr.com/photos/67904872@ ... 912223623/


Top
   
PostPosted: Sun Aug 19, 2018 11:38 am 
Offline
User avatar

Joined: Fri Jun 02, 2017 12:05 pm
Posts: 75
Location: Memphis, Tn., US
photomicro wrote:

This is a good reference if you have not seen it before;

https://www.mccrone.com/mm/an-introduct ... diatoms-2/

Mike


Really appreciate that link Mike. A very good resource.

_________________
"You're never too old to have a happy childhood"
Leitz Wetzlar SM-LUX
Olympus IM
Canon 450D


Top
   
PostPosted: Sun Aug 19, 2018 12:35 pm 
Offline
User avatar

Joined: Fri Jun 02, 2017 12:05 pm
Posts: 75
Location: Memphis, Tn., US
rnabholz wrote:

Be patient waiting for the reaction, it can sometimes take a bit for it to kick off. Resist the urge to add more PD. I have had it take an hour or longer to start, and ..........

Rod


Thanks for the heads up on the reaction times. After a minute or two it would most likely catch me off guard. I should make it a point to always use a catch tray.

_________________
"You're never too old to have a happy childhood"
Leitz Wetzlar SM-LUX
Olympus IM
Canon 450D


Top
   
PostPosted: Sun Aug 19, 2018 2:05 pm 
Offline

Joined: Mon Aug 21, 2017 9:02 pm
Posts: 1956
Hobbyst46 wrote:
Thanks Rod - I will try and search. Curiosity killed the cat... ;)

Apparently the original protocol is described here:
"A new method of concentrating and cleaning diatoms and other organisms" A. van der Werff
Pages 276-277 | Published online: 01 Dec 2017
https://doi.org/10.1080/03680770.1950.11895297

Internationale Vereinigung für theoretische und angewandte Limnologie: Verhandlungen, 12(1), pp. 276–277 (1955)
Quite old.
Alternative publication name:
Societas lnternationalis Limnologiae: International Association for Theoretical and Applied Limnology

_________________
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo


Top
   
PostPosted: Mon Aug 20, 2018 2:47 pm 
Offline
User avatar

Joined: Thu Jan 08, 2015 10:11 pm
Posts: 3066
Location: Iowa USA
jimur wrote:
rnabholz wrote:

Be patient waiting for the reaction, it can sometimes take a bit for it to kick off. Resist the urge to add more PD. I have had it take an hour or longer to start, and ..........

Rod



Thanks for the heads up on the reaction times. After a minute or two it would most likely catch me off guard. I should make it a point to always use a catch tray.



And a significantly over sized container will save you some trouble too.

_________________
Rod Nabholz
http://www.homebuiltastronomy.com
http://www.wildsideiowa.com


Top
   
PostPosted: Mon Aug 20, 2018 3:06 pm 
Offline
User avatar

Joined: Thu Jan 08, 2015 10:11 pm
Posts: 3066
Location: Iowa USA
Hobbyst46 wrote:
Hobbyst46 wrote:
Thanks Rod - I will try and search. Curiosity killed the cat... ;)

Apparently the original protocol is described here:
"A new method of concentrating and cleaning diatoms and other organisms" A. van der Werff
Pages 276-277 | Published online: 01 Dec 2017
https://doi.org/10.1080/03680770.1950.11895297

Internationale Vereinigung für theoretische und angewandte Limnologie: Verhandlungen, 12(1), pp. 276–277 (1955)
Quite old.
Alternative publication name:
Societas lnternationalis Limnologiae: International Association for Theoretical and Applied Limnology


Thanks for the investigation work.

I have also seen the protocol referenced in summaries academic papers on Diatom studies. It seems it has been out there a while.

_________________
Rod Nabholz
http://www.homebuiltastronomy.com
http://www.wildsideiowa.com


Top
   
PostPosted: Mon Aug 20, 2018 6:20 pm 
Offline

Joined: Mon Aug 21, 2017 9:02 pm
Posts: 1956
rnabholz wrote:
Hobbyst46 wrote:
Hobbyst46 wrote:
Thanks Rod - I will try and search. Curiosity killed the cat... ;)

Apparently the original protocol is described here:
"A new method of concentrating and cleaning diatoms and other organisms" A. van der Werff
Pages 276-277 | Published online: 01 Dec 2017
https://doi.org/10.1080/03680770.1950.11895297

Internationale Vereinigung für theoretische und angewandte Limnologie: Verhandlungen, 12(1), pp. 276–277 (1955)
Quite old.
Alternative publication name:
Societas lnternationalis Limnologiae: International Association for Theoretical and Applied Limnology


Thanks for the investigation work.

I have also seen the protocol referenced in summaries academic papers on Diatom studies. It seems it has been out there a while.

The original van Der Werff article being very short and hard to acquire, I looked in some more modern literature. There has been some research in France in 2005-2006 on mixing H2O2 with tiny amounts of dichromate (by N. Frikha and coworkers). They provide evidence that indeed, dichromate combines with H2O2 in a catalytic way: It accelerates the decomposition of H2O2 to oxygen and water, releasing considerable heat. When it is finished, dichromate remains in the mixture (this explains the yellow color of the final liquid after the dichromate reaction). For catalysis, a tiny amount of the agent (dichromate) is sufficient, even if the amount of residual H2O2 is large by comparison.

the research indicated that the reaction rate and the rate of heating of the liquid depend on several conditions (so that, in my opinion the time to start and the intensity could vary from time to time as mentioned by rnabholz). The reaction can get out of control (called "runaway process"). So, although the products are not toxic, it should indeed be carefully approached.

But IMHO, these results show that dichromate does not serve here as oxidizer. Neither does it amplify the oxidative power of H2O2. It does heat the mixture and create a lot of oxygen bubbles. But oxygen bubbles are not powerful oxidizer in this case. They just remove the debris mechanically. So, I agree with zzffnn, that it is equivalent to boiling and that for cleaning diatoms, warming the H2O2-diatom mixture in a water bath, even to the boiling point of the water, is safer and better controlled than the (spectacular) reaction with dichromate.

Like mentioned in protocols, I think that heating the H2O2-containing mixture should be done gradually, taking precaution against splashes of hot corrosive liquid, and only when there is no strong foaming at room temperature. And I agree with photomicro that getting rid of the excess of H2O2 is not an issue, no need to employ dichromate for that. My opinion, until other evidence is found, I would omit the dichromate from the protocol.

_________________
Zeiss Standard GFL+Canon EOS-M10, Olympus VMZ stereo


Top
   
PostPosted: Tue Aug 21, 2018 12:55 am 
Offline
User avatar

Joined: Tue Jun 09, 2015 12:08 am
Posts: 1501
Location: League City, Texas
In your discussions of potassium dichromate in H202, there's one possible factor you utterly fail to address: magic. The additional cleaning action is a result of magic that happens when you dump a few of those mysterious little crystals into your diatom-H202 soup. You can tell it's magic by the way the color instantly changes from tan-ish to deep purple.

Seriously, I like to think the furiously hot boiling grand finale puts a finishing touch on clearing and separation of the valves and girdles, and in this case of using a less than professional grade boiling acid process I'll take all the help I can get. Mind you, I have zero training in chemistry, not very bright besides, and really don't know what the heck I'm doing. But the reaction is entertaining, makes it easier to pretend I do know what I'm doing, and I get very nice diatom strews slides in the end.

_________________
Cheers,
Kurt Maurer
League City, Texas
email: ngc704(at)aol(dot)com
http://sawdustfactory.nfshost.com/microscopes/
https://www.flickr.com/photos/67904872@ ... 912223623/


Top
   
PostPosted: Tue Aug 21, 2018 3:23 am 
Offline
User avatar

Joined: Thu Jan 08, 2015 10:11 pm
Posts: 3066
Location: Iowa USA
I will be watching for news of your trials with the H2O2 only process, and I am rooting for you. I am more than willing to remove a step in the processing if it is found to be unnecessary.

That said, I find myself with Kurt on this for now. Adding PD to room temperature H2O2 and diatom material and watching the bubbling and steam that results, it is hard to believe that it has no effect. I have witnessed a reduction in remaining visible organic particles post reaction. I believe the thermal spike does help separate stubborn girdles and valves as well.

The issues I had in the beginning managing the reaction were completely the result of my ignorance and inexperience with the chemicals and process. I caution those inquiring only to save them the same troubles, not to paint a picture of great peril or impending doom for all that dare tread here ;^). Use a significantly over sized vessel, and conservative amount of PD, and be patient, and all will be well.

In the end this process is very productive for me,and produced nice clean and separated frustules, but I am open to making a change should it be proven just as effective.

Good discussion.

Rod

_________________
Rod Nabholz
http://www.homebuiltastronomy.com
http://www.wildsideiowa.com


Top
   
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 24 posts ] 

All times are UTC


Who is online

Users browsing this forum: Google [Bot] and 7 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Limited