Question

Asked 20 May 2022

Ana T. Luís

Ana T. Luís

- University of Huelva

Hi everyone, does anyone know an alternative to Naphrax for diatom mounting?

Hi everyone, does anyone know an alternative to Naphrax for diatom mounting?

Diatoms

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Hasna Chabaca

Mohamed-Cherif Messaadia University

Hello

I was using a transparent nail polish , I think It's very easy to get it.

Try it and let me know

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Popular answers (1)

Lane Allen

University of Colorado Boulder

Canada Balsam is also not an acceptable alternative to Naphrax. It is a great mounting medium for tissue samples, because it has nearly the same refractive index as glass, which is the opposite of what you are looking for in a mounting medium for diatoms. Entellan has a RI of ~1.5 at the most, so I would advise against using it either. I would like to point out that although Naphrax seems expensive, it only takes about three drops to make a slide, so a 400$ bottle will easily make several thousand slides. You could also purchase a smaller bottle for less that 100$ which would probably be more than enough for a single project. The materials for a Naphrax slide cost less that a dollar altogether if you exclude oxidants used to digest samples. The most expensive part of a Naphrax slide is the time that goes into making it. This is not an area where you should consider cutting corners if you intend to assess community structure. If you want to publish on diatom community structure, invest in a proper mounting medium, one with a high RI, that will not leave air bubbles in the diatoms (i.e. Meltmount). If you do not feel comfortable preparing Naphrax slides due to safety concerns, I recommend outsourcing the process of slidemaking to another lab that does this on a regular basis.

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All Answers (37)

Ana T. Luís

University of Huelva

I need one with minimum refractive index of 1.74...

But thanks for your help!

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Ana T. Luís

University of Huelva

Great. Many thanks

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Janne Soininen

University of Helsinki

I remember there was also Dirax earlier..

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Cüneyt Nadir Solak

Dumlupinar University

Hi Ana,

As ı know, nowadays Ehsan (Atazadeh) (ehsan.atazadeh@gmail.com) is trying to prepare something similar and he got some results.

Cordial

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Ana T. Luís

University of Huelva

Many thanks colleagues for your help. It is extremely expensive now, the Naphrax. The price raised from 200€ to 600€ due to shipping

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Saúl Blanco

University of Leon

Hyrax has a RI of 1.70-1.75

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Ana T. Luís

University of Huelva

Thanks to all for the help

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Lorena Rebolledo

Instituto Antartico Chileno

Norland optical adhesive

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Michael Kloster

University of Duisburg-Essen

Speedax 1,75 AC is new on the market, with a RI of 1,75. It is easy to handle and uses acetone as solvent (for shipping a acetone-free version seems to be available).

See:

https://www.tmg-tuebingen.de/wp-content/uploads/2021/06/Speedax_175_AC-DE.pdf

and

https://www.tmg-tuebingen.de/neues-hochbrechendes-einschlussmittel-speedax/

(alas, only in German, but I have an English product flyer if you need that).

Drawbacks are that you need to seal the coverslip because the mountant might dissolve in immersion oil and end up on the objective lens. Also, it does not harden completely, so it might "creep" slightly over the years esp. if you store the slides not horizontally, so it is not perfect for "permanent slides".

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3 Recommendations

Émilie Saulnier-Talbot

Université Laval

I use Meltmount. It's a thermoplastic available with a RI of 1.74 (same as Naphrax). Cheap and easy to use!

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Nitika Bhardwaj

Panjab University

DPX mountant

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Kim Sunghyoun

Kunsan National University

I tried Fisher Chemical™ Permount™ Mounting Medium and it worked just fine. The RI is 1.522, which is slightly lower than Naflax. The solvent is toluene.

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Michael Kloster

University of Duisburg-Essen

Just as a quick note: Amorphous diatom silica has a RI of 1.43. The higher the difference between RI of diatoms and mounting medium, the better the contrast. Mounting media with a RI substantially lower than 1.7 might work for strongly silicified diatoms, but are not optimal for weakly silicified ones.

Another thing worth to consider: Non-rigid mountants (e.g. thermoplastics) are not a good idea if you want to preserve your samples for a long time. In the Hustedt diatom collection we had samples mountet in Naphrax for >100 years, which were fine (even though some people reported problems with Naphrax crystalizing after some years, a problem I never encountered, maybe depends on its quality/purity), and samples mounted in Norland Optical 61, which is claimed to harden 100%, but drove me crazy because when I re-scanned slides after 2 years of vertical storage and most of the diatoms had moved by 5-10 microns. With MeltMount etc. I assume this is even worse. Nevertheless, if you plan to dispose of your slides after a year or so and store them horizontally, non-rigid mountants should work for you.

A third thing to consider is the viscosity of the mountant. Norland optical adhesives (e.g. NOA 61) are often used for standard analyses because they are easy to apply and do not contain toluene, but quite often they will not enter the cavity of complete frustules, leaving them filled with air, which might pose a problem because this might obscure important structural details. Also, the Norland adhesives have a very limited shelf live of (mostly) only a few months, and they really degrade in quality after that (this might have caused the problem I mentioned before).

After trying several alternatives, we decided to switch back to Naphrax, even though it is expensive, toxic, hard to find, and there probably was a problem with a complete batch of Naphrax which was bad/impure but nevertheless had been put on the market.

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2 Recommendations

Reinhard Pienitz

Université Laval

Hyrax

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Lane Allen

University of Colorado Boulder

Hyrax and Zrax are great, except they are no longer made. Norland Optical Adhesive is not an acceptable alternative to Naphrax. The RI is too low and you cannot resolve key features on lightly silicified diatoms. I know researchers who have used both Naphrax and Meltmount and none of them have had anything good to say about it. I don't know about DPX or Permount but as Michael stated, anything substantially lower that 1.7 will not provide satisfactory results. I've been told that certain types of cinnamon oil can be used to make temporary diatom slides, but be sure to get the one with the highest RI available.

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Lothar Täuscher

Humboldt-Universität zu Berlin; Landesamt für Umweltschutz Sachsen-Anhalt; Botanischer Verein von Berlin und Brandenburg

"Kanadabalsam" or Caedax or Entellan.

Best regards Lothar

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Lothar Täuscher

Humboldt-Universität zu Berlin; Landesamt für Umweltschutz Sachsen-Anhalt; Botanischer Verein von Berlin und Brandenburg

"Kanadabalsam" or Caedax or Entellan.

Best regards Lothar

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Lothar Täuscher

Humboldt-Universität zu Berlin; Landesamt für Umweltschutz Sachsen-Anhalt; Botanischer Verein von Berlin und Brandenburg

"Kanadabalsam" or Caedax or Entellan

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Lothar Täuscher

Humboldt-Universität zu Berlin; Landesamt für Umweltschutz Sachsen-Anhalt; Botanischer Verein von Berlin und Brandenburg

"Kanadabalsam" or Caedax or Entellan

- Dr. Lothar Täuscher_2022_Engli

sh.pdf

337 kB

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Lane Allen

University of Colorado Boulder

Canada Balsam is also not an acceptable alternative to Naphrax. It is a great mounting medium for tissue samples, because it has nearly the same refractive index as glass, which is the opposite of what you are looking for in a mounting medium for diatoms. Entellan has a RI of ~1.5 at the most, so I would advise against using it either. I would like to point out that although Naphrax seems expensive, it only takes about three drops to make a slide, so a 400$ bottle will easily make several thousand slides. You could also purchase a smaller bottle for less that 100$ which would probably be more than enough for a single project. The materials for a Naphrax slide cost less that a dollar altogether if you exclude oxidants used to digest samples. The most expensive part of a Naphrax slide is the time that goes into making it. This is not an area where you should consider cutting corners if you intend to assess community structure. If you want to publish on diatom community structure, invest in a proper mounting medium, one with a high RI, that will not leave air bubbles in the diatoms (i.e. Meltmount). If you do not feel comfortable preparing Naphrax slides due to safety concerns, I recommend outsourcing the process of slidemaking to another lab that does this on a regular basis.

Cite

3 Recommendations

R. Ranjith Kumar

Madras Christian College

DPX is another alternative for Diatom mounting

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Yuriko Martinez

Universidad Autónoma de Baja California Sur

Pleurax

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Özgür Eren Zariç

Gaziantep University

Zrax, pleurax

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Alejandra Goldenberg Vilar

University of Cantabria

Fisher permount mounting media. The refraction index is a bit lower than the one of Naphrax but is good enough for diatom identification.

Cheers!

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Nitika Bhardwaj

Panjab University

You can use DPX.

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Ehsan Atazadeh

University of Tabriz

Hi, we produce Naphrax for diatom mounting. Please see attached file.

Feel free to contact me:

University of Tabriz, Iran

atazadeh@tabrizu.ac.ir

- Naphra

x.jpg

252 kB

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Ehsan Atazadeh

University of Tabriz

If you need Naphrax with quality, I can supply it with low price.

- Naphrax(

2).jpg

2.11 MB

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Ana T. Luís

University of Huelva

What is the price, please?

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Ehsan Atazadeh

University of Tabriz

Hi Ana,

Thanks for your question.

200 ml = 200 Euros

100 ml = 100 Euros

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Samsul Islam

Dhaka University of Engineering & Technology

Naphrax is a widely used medium for mounting diatoms on microscope slides. However, Naphrax has been discontinued, and it might be challenging to find it commercially available. Fortunately, there are alternative mounting media that can be used for mounting diatoms for microscopic observation. Some commonly used alternatives include:

1. Naphrax Substitute: Some companies have developed Naphrax substitutes that aim to replicate the properties of the original Naphrax medium. These substitutes may offer similar refractive index and mounting qualities.

2. Pleurax: Pleurax is a mounting medium that is commonly used as an alternative to Naphrax. It has similar properties and is suitable for mounting diatoms for light microscopy.

3. Refractive Index Matching Media: There are various refractive index matching media available commercially. These media aim to match the refractive index of diatom frustules, reducing the light scattering during microscopic observation.

4. Glycerin Jelly: A mixture of glycerin and gelatin can be used as a simple and low-cost mounting medium for diatoms.

5. Silicone Oil: Some researchers use silicone oil as a mounting medium for diatoms. It has a similar refractive index to diatoms, making it suitable for light microscopy.

6. Entellan: Entellan is a synthetic resin mounting medium that is commonly used in histology and can also be used for mounting diatoms.

When selecting an alternative mounting medium, consider the refractive index, viscosity, transparency, and the compatibility of the medium with the specific objectives of your microscopic observation. It's always a good idea to test different mounting media on a subset of your diatom samples before committing to a large-scale use.

Since the availability of mounting media may vary depending on your location and local suppliers, it's best to check with microscopy or laboratory supply companies for the most suitable alternative to Naphrax for your specific needs. Additionally, scientific literature and online forums can be valuable resources for discovering alternative mounting methods used by researchers in the field of diatom analysis.

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Lane Allen

University of Colorado Boulder

https://www.naphrax.co.uk/shop/Diatom_Mountants.html

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Ehsan Atazadeh

University of Tabriz

Hi, Please see attached file.

- Naphra

x.jpg

457 kB

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Nitika Bhardwaj

Panjab University

DPX Mountatnt

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Hasna Chabaca

Mohamed-Cherif Messaadia University

Hello

I was using a transparent nail polish , I think It's very easy to get it.

Try it and let me know

Cite