# Filter paper - Quantitative vs Qualitative



## gold4mike (Mar 4, 2010)

I saw a recent post that mentioned nitric acid available from Elemental Scientific in Wisconsin so I visited their website to see what else might be available. I'm in need of more filters for my Buchner funnel and found that they list slow flow, medium flow and fast flow filters both in "Qualitative" and "Quantitative" varieties. I assume that the slow flow will be the least porous and will filter out more of the fine dust or flake I may produce.

What is the difference between the quantitative and qualitative types? 

I use my Buchner funnel with a vacuum pump that was in a lot of material I was given at the local hospital so I can maintain good, steady suction to keep the filter sealed.

Thanks in advance for any advice!

Mike


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## Irons (Mar 4, 2010)

gold4mike said:


> I saw a recent post that mentioned nitric acid available from Elemental Scientific in Wisconsin so I visited their website to see what else might be available. I'm in need of more filters for my Buchner funnel and found that they list slow flow, medium flow and fast flow filters both in "Qualitative" and "Quantitative" varieties. I assume that the slow flow will be the least porous and will filter out more of the fine dust or flake I may produce.
> 
> What is the difference between the quantitative and qualitative types?
> 
> ...


Typically, the quantitative paper is a low ash composition so that, after ignition, the residue can be weighed. They also tend to be very slow.


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## gold4mike (Mar 4, 2010)

Thank you for the very quick reply!


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## Anonymous (Mar 31, 2010)

I have been directed to use Whatman #51 Filter Paper but have no idea where to find it. Help!
Thanks much, haroldg


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## Harold_V (Apr 1, 2010)

haroldg said:


> I have been directed to use Whatman #51 Filter Paper but have no idea where to find it. Help!
> Thanks much, haroldg


If memory serves, Whatman #51 is ultra retentive, and suited for use with vacuum. It's not going to be cheap. I used to use Whatman #5 for filtering my gold solutions when doing a second refining. Prior to that, I always used a Whatman #2, which is much faster, yet very retentive. The #5 was more than 50¢ for a single 32 cm circle back then, which was the early 90's. Make sure that's what you really need. If you filter dirty solutions, it's likely to be very troublesome. 

You will probably find it by exploring some of the chemical supply stores. I used to buy it from Sergeant Welch. Haven't done business with them since '94, however, so I don't have a clue if they might still have it, or not. 

Welcome to the forum. Nice name you have! 8) 

Harold


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## Irons (Apr 1, 2010)

Harold_V said:


> haroldg said:
> 
> 
> > I have been directed to use Whatman #51 Filter Paper but have no idea where to find it. Help!
> ...



It appears that Whatman 51 is no longer being produced. Type 50 is essentially the same with a 2.7 micron particle retention.

http://www.whatman.com/QuantitativeFilterPapersHardenedLowAshGrades.aspx


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## Lou (Apr 6, 2010)

Price. :mrgreen: 

Joking aside, most quantitative papers are used for ashing and other ''constant mass'' applications. The best thing to do is to call Whatman up and tell them what you're using it for--you'll be surprised by just how much these fellows know! They've heard it all.


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## nickvc (Apr 7, 2010)

Lou said:


> Price. :mrgreen:
> 
> Joking aside, most quantitative papers are used for ashing and other ''constant mass'' applications. The best thing to do is to call Whatman up and tell them what you're using it for--you'll be surprised by just how much these fellows know! They've heard it all.


Excellent advice, not everyone we use in this hobby/business is out to screw us :shock:


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