From: James Saccardo <James.Saccardo**At_Symbol_Here**CSI.CUNY.EDU>
Subject: Re: [DCHAS-L] Re; amorphous silica
Date: June 28, 2012 4:35:16 PM EDT
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: <C0972A45C7DC7040BB5D18BB89552EA10425FD8A**At_Symbol_Here**019-SN2MPN1-063.019D.MGD.MSFT.NET>

Our columns use flammable and halogenated solvents. Inevitably there are trace amounts of solvent adsorbed onto the silica. We discourage drying out of silica wet with solvent in the hood as this can be considered treatment. The wet silica is dumped into 5 gallon DOT rated carboys and sent off site with a D001 and applicable F002 or F005 codes. Since many columns use chloroform, the process silica gel also carries the D022 code.

Dumping wet silica out of the top of the column is not the easiest task, but it is not that difficult either. Using a wash bottle with water also makes it more manageable, keeping the amount of water to a minimum.

The waste determination must consider the solvent system and residue contained.
I hope that is useful.

Be Well,

-----Original Message-----
From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Frank Coppo
Sent: Thursday, June 28, 2012 9:49 AM
Subject: Re: [DCHAS-L] Re; amorphous silica

Folks -

I'd have to believe this would be considered RCRA regulated hazardous waste (it is here in PA), not appropriate for the trash (municipal waste), regardless of mass/volume.

Best regards, Frank

-----Original Message-----
From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Secretary, ACS Division of Chemical Health and Safety
Sent: Wednesday, June 27, 2012 1:27 PM
Subject: [DCHAS-L] Re; amorphous silica

From: Rita Kay Calhoun
Subject: RE: [DCHAS-L] Toxic dust handling
Date: June 27, 2012 12:10:28 PM EDT

What about disposal of silica gel? If the column is stripped of sample, can it be sealed in a bag and disposed of in the trash? I'm talking about small amounts, certainly less than 2-300 grams.


From: Keith Rickabaugh
Subject: amorphous silica correction - - - RE: [DCHAS-L] Toxic dust handling
Date: June 27, 2012 12:29:44 PM EDT

I disagree with amorphous silica being cited as a "nuisance dust".

Independent of any toxicity issues, amorphous silica is a regulated substance by OSHA as per 29 CFR 1910.1000 (see table z-3). However, I believe that this is rarely (if ever) enforced. Even though there are reasonable arguments that this OSHA PEL reference value is outdated and may not be relevant - it is still the law.

The OSHA PEL is a calculated value that is based off of the percent of amorphous silica material in the particulate: 80 mg / % amorphous silica.

Many people are confused by this formula as they incorrectly think that the % silica in the formula is for crystalline silica.

If working with 100% amorphous silica, the PEL would 0.8 mg per cubic meter.

This is the one and only instance that I have noted that the OSHA PEL is actually lower than ACGIH TLV or NIOSH REL values.

See links below if interested in learning more:;94

Keith Rickabaugh

Technical Director, Materials & Analytical Services

RJ Lee Group

724.325.1776 Office
724.387.1841 Direct
724.309.6732 Mobile
724.733.1799 Fax

350 Hochberg Road | Monroeville, PA 15146

Please let us know if we've met your expectations on your project by visiting our Customer Survey.



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